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 In any of cases, perhaps most, Foundationalism is a view concerning the ‘structure’ of the system of justified belief possessed by a given individual. Such a system is divided into ‘foundation’ and ‘superstructure’, so related that beliefs in the latter depend on the former for their justification but not vice versa. However, the view is sometimes stated in terms of the structure of ‘knowledge’ than of justified belief. If knowledge is true justified belief (plus, perhaps, some further condition), one may think of knowledge as exhibiting a Foundationalist structure by virtue of the justified belief it involves. In any event, the construing doctrine concerning the primary justification is layed the groundwork as affording the efforts of belief, though in feeling more free, we are to acknowledge the knowledgeable infractions that will from time to time be worthy in showing .
 The first step toward a more explicit statement of the position is to distinguish between ‘mediate’ (indirect) and ‘immediate’ (direct) justification of belief. To say that a belief is mediately justified is to any that it s justified by some appropriate relation to other justified beliefs, i.e., by being inferred from other justified beliefs that provide adequate support for it, or, alternatively, by being based on adequate reasons. Thus, if my reason for supposing that you are depressed is that you look listless, speak in an unaccustomedly flat tone of voice, exhibit no interest in things you are usually interested in, etc., then my belief that you are depressed is justified, if, at all, by being adequately supported by my justified belief that you look listless, speak in a flat tone of voice. . . .
 A belief is immediately justified, on the other hand, if its justification is of another sort, e.g., if it is justified by being based on experience or if it is ‘self-justified’. Thus my belief that you look listless may not be based on anything else I am justified in believing but just on the cay you look to me. And my belief that 2 + 3 = 5 may be justified not because I infer it from something else, I justifiably believe, but simply because it seems obviously true to me.
 In these terms we can put the thesis of Foundationalism by saying that all mediately justified beliefs owe their justification, ultimately to immediately justified beliefs. To get a more detailed idea of what this amounts to it will be useful to consider the most important argument for Foundationalism, the regress argument. Consider a mediately justified belief that ‘p’ (we are using lowercase letters as dummies for belief contents). It is, by hypothesis, justified by its relation to one or more other justified beliefs, ‘q’ and ‘r’. Now what justifies each of these, e.g., q? If it too is mediately justified that is because it is related accordingly to one or subsequent extra justified beliefs, e.g., ‘s’. By virtue of what is ‘s’ justified? If it is mediately justified, the same problem arises at the next stage. To avoid both circularity and an infinite regress, we are forced to suppose that in tracing back this chain we arrive at one or more immediately justified beliefs that stop the regress, since their justification does not depend on any further justified belief.
 According to the infinite regress argument for Foundationalism, if every justified belief could be justified only by inferring it from some further justified belief, there would have to be an infinite regress of justifications: Because there can be no such regress, there must be justified beliefs that are not justified by appeal to some further justified belief. Instead, they are non-inferentially or immediately justified, they are basic or foundational, the ground on which all our other justifiable beliefs are to rest.
 Variants of this ancient argument have persuaded and continue to persuade many philosophers that the structure of epistemic justification must be foundational. Aristotle recognized that if we are to have knowledge of the conclusion of an argument in the basis of its premisses, we must know the premisses. But if knowledge of a premise always required knowledge of some further proposition, then in order to know the premise we would have to know each proposition in an infinite regress of propositions. Since this is impossible, there must be some propositions that are known, but not by demonstration from further propositions: There must be basic, non-demonstrable knowledge, which grounds the rest of our knowledge.
 Foundationalist enthusiasms for regress arguments often overlook the fact that they have also been advanced on behalf of scepticism, relativism, fideisms, conceptualism and Coherentism. Sceptics agree with foundationalist’s both that there can be no infinite regress of justifications and that nevertheless, there must be one if every justified belief can be justified only inferentially, by appeal to some further justified belief. But sceptics think all true justification must be inferential in this way  -the foundationalist’s talk of immediate justification merely overshadows the requiring of any rational justification properly so-called. Sceptics conclude that none of our beliefs is justified. Relativists follow essentially the same pattern of sceptical argument, concluding that our beliefs can only be justified relative to the arbitrary starting assumptions or presuppositions either of an individual or of a form of life.
 Regress arguments are not limited to epistemology. In ethics there is Aristotle’s regress argument (in ‘Nichomachean Ethics’) for the existence of a single end of rational action. In metaphysics there is Aquinas’s regress argument for an unmoved mover: If a mover that it is in motion, there would have to be an infinite sequence of movers each moved by a further mover, since there can be no such sequence, there is an unmoved mover. A related argument has recently been given to show that not every state of affairs can have an explanation or cause of the sort posited by principles of sufficient reason, and such principles are false, for reasons having to do with their own concepts of explanation (Post, 1980; Post, 1987).
 The premise of which in presenting Foundationalism as a view concerning the structure ‘that is in fact exhibited’ by the justified beliefs of a particular person has sometimes been construed in ways that deviate from each of the phrases that are contained in the previous sentence. Thus, it is sometimes taken to characterise the structure of ‘our knowledge’ or ‘scientific knowledge’, rather than the structure of the cognitive system of an individual subject. As for the other phrase, Foundationalism is sometimes thought of as concerned with how knowledge (justified belief) is acquired or built up, than with the structure of what a person finds herself with at a certain point. Thus some people think of scientific inquiry as starting with the recordings of observations (immediately justified observational beliefs), and then inductively inferring generalizations. Again, Foundationalism is sometimes thought of not as a description of the finished product or of the mode of acquisition, but rather as a proposal for how the system could be reconstructed, an indication of how it could all be built up from immediately justified foundations. This last would seem to be the kind of Foundationalism we find in Descartes. However, Foundationalism is most usually thought of in contemporary Anglo-American epistemology as an account of the structure actually exhibited by an individual’s system of justified belief.
 It should also be noted that the term is used with a deplorable looseness in contemporary, literary circles, even in certain corners of the philosophical world, to refer to anything from realism  -the view that reality has a definite constitution regardless of how we think of it or what we believe about it to various kinds of ‘absolutism’ in ethics, politics, or wherever, and even to the truism that truth is stable (if a proposition is true, it stays true).
 Since Foundationalism holds that all mediate justification rests on immediately justified beliefs, we may divide variations in forms of the view into those that have to do with the immediately justified beliefs, the ‘foundations’, and those that have to do with the modes of derivation of other beliefs from these, how the ‘superstructure’ is built up. The most obvious variation of the first sort has to do with what modes of immediate justification are recognized. Many treatments, both pro and con, are parochially restricted to one form of immediate justification  -self-evidence, self-justification (self-warrant), justification by a direct awareness of what the belief is about, or whatever. It is then unwarrantly assumed by critics that disposing of that one form will dispose of Foundationalism generally (Alston, 1989, ch. 3). The emphasis historically has been on beliefs that simply ‘record’ what is directly given in experience (Lewis, 1946) and on self-evident propositions (Descartes’ ‘clear and distinct perceptions and Locke’s ‘Perception of the agreement and disagreement of ideas’). But self-warrant has also recently received a great deal of attention (Alston 1989), and there is also a reliabilist version according to which a belief can be immediately justified just by being acquired by a reliable belief-forming process that does not take other beliefs as inputs (BonJour, 1985, ch. 3).
 Foundationalisms also differ as to what further constraints, if any, are put on foundations. Historically, it has been common to require of the foundations of knowledge that they exhibit certain ‘epistemic immunities’, as we might put it, immunity from error, refutation or doubt. Thus Descartes, along with many other seventeenth and eighteenth-century philosophers, took it that any knowledge worthy of the name would be based on cognations the truth of which is guaranteed (infallible), that were maximally stable, immune from ever being shown to be mistaken, as incorrigible, and concerning which no reasonable doubt could be raised (indubitable). Hence the search in the ‘Meditations’ for a divine guarantee of our faculty of rational intuition. Criticisms of Foundationalism have often been directed at these constraints: Lehrer, 1974, Will, 1974? Both responded to in Alston, 1989. It is important to realize that a position that is Foundationalist in a distinctive sense can be formulated without imposing any such requirements on foundations.
 There are various ways of distinguishing types of Foundationalist epistemology by the use of the variations we have been enumerating. Plantinga (1983), has put forwards an influential innovation of criterial Foundationalism, specified in terms of limitations on the foundations. He construes this as a disjunction of ‘ancient and medieval Foundationalism’, which takes foundations to comprise what is self-evidently and ‘evident to he senses’, and ‘modern Foundationalism’ that replaces ‘evidently to the senses’ with ‘incorrigible’, which in practice was taken to apply only to beliefs about one’s present states of consciousness. Plantinga himself developed this notion in the context of arguing those items outside this territory, in particular certain beliefs about God, could also be immediately justified. A popular recent distinction is between what is variously called ‘strong’ or ‘extreme’ Foundationalism and ‘moderate’, ‘modest’ or ‘minimal’ Foundationalism, with the distinction depending on whether various epistemic immunities are required of foundations. Finally, its distinction is ‘simple’ and ‘iterative’ Foundationalism (Alston, 1989), depending on whether it is required of a foundation only that it is immediately justified, or whether it is also required that the higher level belief that the firmer belief is immediately justified is itself immediately justified. Suggesting only that the plausibility of the stronger requirement stems from a ‘level confusion’ between beliefs on different levels.
 The classic opposition is between Foundationalism and Coherentism. Coherentism denies any immediate justification. It deals with the regress argument by rejecting ‘linear’ chains of justification and, in effect, taking the total system of belief to be epistemically primary. A particular belief is justified yo the extent that it is integrated into a coherent system of belief. More recently into a pragmatist like John Dewey has developed a position known as contextualism, which avoids ascribing any overall structure to knowledge. Questions concerning justification can only arise in particular context, defined in terms of assumptions that are simply taken for granted, though they can be questioned in other contexts, where other assumptions will be privileged.
 Foundationalism can be attacked both in its commitment to immediate justification and in its claim that all mediately justified beliefs ultimately depend on the former. Though, it is the latter that is the position’s weakest point, most of the critical fire has been detected to the former. As pointed out about much of this criticism has been directly against some particular form of immediate justification, ignoring the possibility of other forms. Thus, much anti-foundationalist artillery has been directed at the ‘myth of the given’. The idea that facts or things are ‘given’ to consciousness in a pre-conceptual, pre-judgmental mode, and that beliefs can be justified on that basis (Sellars, 1963). The most prominent general argument against immediate justification is a ‘level ascent’ argument, according to which whatever is taken ti immediately justified a belief that the putative justifier has in supposing to do so. Hence, since the justification of the higher level belief after all (BonJour, 1985). We lack adequate support for any such higher level requirements for justification, and if it were imposed we would be launched on an infinite undergo regress, for a similar requirement would hold equally for the higher level belief that the original justifier was efficacious.
 Coherence is a major player in the theatre of knowledge. There are coherence theories of belief, truth, and justification. These combine in various ways to yield theories of knowledge. We will proceed from belief through justification to truth. Coherence theories of belief are concerned with the content of beliefs. Consider a belief you now have, the beliefs that you are reading a page in a book, so what makes that belief the belief that it is? What makes it the belief that you are reading a page in a book than the belief hat you have a monster in the garden?
 One answer is that the belief has a coherent place or role in a system of beliefs. Perception has an influence on belief. You respond to sensory stimuli by believing that you are reading a page in a book rather than believing that you have a centaur in the garden. Belief has an influence on action. You will act differently if you believe that you are reading a page than if you believe something about a centaur. Perspicacity and action undermine the content of belief, however, the same stimuli may produce various beliefs and various beliefs may produce the same action. The role that gives the belief the content it has in the role it plays in a network of relations to the beliefs, the role in inference and implications, for example, I refer different things from believing that I am inferring different things from believing that I am reading a page in a book than from any other beliefs, just as I infer that belief from any other belief, just as I infer that belief from different things than I infer other beliefs from.
 The input of perception and the output of an action supplement the centre role of the systematic relations the belief has to other beliefs, but it is the systematic relations that give the belief the specific content it has. They are the fundamental source of the content of beliefs. That is how coherence comes in. A belief has the content that it does because of the way in which it coheres within a system of beliefs (Rosenberg, 1988). We might distinguish weak coherence theories of the content of beliefs from strong coherence theories. Weak coherence theories affirm that coherences are one-determinant of the content of belief. Strong coherence theories of the contents of belief affirm that coherence is the sole determinant of the content of belief.
 When we turn from belief to justification, we are in confronting a corresponding group of similarities fashioned by their coherences motifs. What makes one belief justified and another not? The answer is the way it coheres with the background system of beliefs. Again, there is a distinction between weak and strong theories of coherence. Weak theories tell ‘us’ that the way in which a belief coheres with a background system of beliefs is one determinant of justification, other typical determinants being perception, memory and intuition. Strong theories, by contrast, tell ‘us’ that justification is solely a matter of how a belief coheres with a system of beliefs. There is, however, another distinction that cuts across the distinction between weak and strong coherence theories of justification. It is the distinction between positive and negative coherence theories (Pollock, 1986). A positive coherence theory tells ‘us’ that if a belief coheres with a background system of belief, then the belief is justified. A negative coherence theory tells ‘us’ that if a belief fails to cohere with a background system of beliefs, then the belief is not justified. We might put this by saying that, according to a positive coherence theory, coherence has the power to produce justification, while according to a negative coherence theory, coherence has only the power to nullify justification.
 A strong coherence theory of justification is a combination of a positive and a negative theory that tells ‘us’ that a belief is justified if and only if it coheres with a background system of beliefs.
 Traditionally, belief has been of epistemological interest in its propositional guise: ‘S’ believes that ‘p’, where ‘p’ is a proposition toward which an agent, ‘S’, exhibits an attitude of acceptance. Not all belief is of this sort. If I trust what you say, I believe you. And someone may believe in Mrs. Thatcher, or in a free-market economy, or in God. It is sometimes supposed that all belief is ‘reducible’ to propositional belief, belief-that. Thus, my believing you might be thought a matter of my believing, perhaps, that what you say is true, and your belief in free-markets or in God, a matter of your believing that free-market economy’s are desirable or that God exists.
 It is doubtful, however, that non-propositional believing can, in every case, be reduced in this way. Debate on this point has tended to focus on an apparent distinction between ‘belief-that’ and ‘belief-in’, and the application of this distinction to belief in God. Some philosophers have followed Aquinas ©. 1225-74), in supposing that to believe in, and God is simply to believe that certain truths hold: That God exists, that he is benevolent, etc. Others (e.g., Hick, 1957) argue that belief-in is a distinctive attitude, one that includes essentially an element of trust. More commonly, belief-in has been taken to involve a combination of propositional belief together with some further attitude.
 H.H. Price (1969) defends the claims that there are different sorts of ‘belief-in’, some, but not all, reducible to ‘beliefs-that’. If you believe in God, you believe that God exists, that God is good, etc., but, according to Price, your belief involves, in addition, a certain complex pro-attitude toward its object. One might attempt to analyse this further attitude in terms of additional beliefs-that: ‘S’ believes in ‘χ’ just in case (1) ‘S’ believes that ‘χ’ exists (and perhaps holds further factual beliefs about (χ): (2)’S’ believes that ‘χ’ is good or valuable in some respect, and (3) ‘S’ believes that χ’s being good or valuable in this respect is itself is a good thing. An analysis of this sort, however, fails adequately to capture the further affective component of belief-in. Thus, according to Price, if you believe in God, your belief is not merely that certain truths hold, you posses, in addition, an attitude of commitment and trust toward God.
 Notoriously, belief-in outruns the evidence for the corresponding belief-that. Does this diminish its rationality? If belief-in presupposes belief-that, it might be thought that the evidential standards for the former must be, at least as high as standards for the latter. And any additional pro-attitude might be thought to require a further layer of justification not required for cases of belief-that.
 Some philosophers have argued that, at least for cases in which belief-in is synonymous with faith (or faith-in), evidential thresholds for constituent propositional beliefs are diminished. You may reasonably have faith in God or Mrs. Thatcher, even though beliefs about their respective attitudes, were you to harbour them, would be evidentially substandard.
 Belief-in may be, in general, less susceptible to alternations in the face of unfavourable evidence than belief-that. A believer who encounters evidence against God’s existence may remain unshaken in his belief, in part because the evidence does not bear on his pro-attitude. So long as this is united with his belief that God exists, the belief may survive epistemic buffeting-and reasonably so in a way that an ordinary propositional belief-that would not.
 At least two large sets of questions are properly treated under the heading of epistemological religious beliefs. First, there is a set of broadly theological questions about the relationship between faith and reason, between what one knows by way of reason, broadly construed, and what one knows by way of faith. These theological questions may as we call theological, because, of course, one will find them of interest only if one thinks that in fact there is such a thing as faith, and that we do know something by way of it. Secondly, there is a whole set of questions having to do with whether and to what degree religious beliefs have warrant, or justification, or positive epistemic status. The second, is seemingly as an important set of a theological question is yet spoken of faith.
 Epistemology, so we are told, is theory of knowledge: Its aim is to discern and explain that quality or quantity enough of which distinguishes knowledge from mere true belief. We need a name for this quality or quantity, whatever precisely it is, call it ‘warrant’. From this point of view, the epistemology of religious belief should centre on the question whether religious belief has warrant, an if it does, hoe much it has and how it gets it. As a matter of fact, however, epistemological discussion of religious belief, at least since the Enlightenment (and in the Western world, especially the English-speaking Western world) has tended to focus, not on the question whether religious belief has warrant, but whether it is justified. More precisely, it has tended to focus on the question whether those properties enjoyed by theistic belief  -the belief that there exists a person like the God of traditional Christianity, Judaism and Islam: An almighty Law Maker, or an all-knowing and most wholly benevolent and a loving spiritual person who has created the living world. The chief question, therefore, has ben whether theistic belief is justified, the same question is often put by asking whether theistic belief is rational or rationally acceptable. Still further, the typical way of addressing this question has been by way of discussing arguments for or and against the existence of God. On the pro side, there are the traditional theistic proofs or arguments: The ontological, cosmological and teleological arguments, using Kant’s terms for them. On the other side, the anti-theistic side, the principal argument is the argument from evil, the argument that is not possible or at least probable that there be such a person as God, given all the pain, suffering and evil the world displays. This argument is flanked by subsidiary arguments, such as the claim that the very concept of God is incoherent, because, for example, it is impossible that there are the people without a body, and Freudian and Marxist claims that religious belief arises out of a sort of magnification and projection into the heavens of human attributes we think important.
 But why has discussion centred on justification rather than warrant? And precisely what is justification? And why has the discussion of justification of theistic belief focussed so heavily on arguments for and against the existence of God?
 As to the first question, we can see why once we see that the dominant epistemological tradition in modern Western philosophy has tended to ‘identify’ warrant with justification. On this way of looking at the matter, warrant, that which distinguishes knowledge from mere true belief, just ‘is’ justification. Belief theory of knowledge-the theory according to which knowledge is justified true belief has enjoyed the status of orthodoxy. According to this view, knowledge is justified truer belief, therefore any of your beliefs have warrant for you if and only if you are justified in holding it.
 But what is justification? What is it to be justified in holding a belief? To get a proper sense of the answer, we must turn to those twin towers of western epistemology. René Descartes and especially, John Locke. The first thing to see is that according to Descartes and Locke, there are epistemic or intellectual duties, or obligations, or requirements. Thus, Locke:
 Faith is nothing but a firm assent of the mind, which if it is regulated, A is our duty, cannot be afforded to anything, but upon good reason: And cannot be opposite to it, he that believes, without having any reason for believing, may be in love with his own fanciers: But, neither seeks truth as he ought, nor pats the obedience due his maker, which would have him use those discerning faculties he has given him: To keep him out of mistake and error. He that does this to the best of his power, however, he sometimes lights on truth, is in the right but by chance: And I know not whether the luckiest of the accidents will excuse the irregularity of his proceeding. This, at least is certain, that he must be accountable for whatever mistakes he runs into: Whereas, he that makes use of the light and faculties God has given him, by seeks sincerely to discover truth, by those helps and abilities he has, may have this satisfaction in doing his duty as rational creature, that though he should miss truth, he will not miss the reward of it.  For he governs his assent right, and places it as he should, who in any case or matter whatsoever, believes or disbelieves, according as reason directs him. He manages otherwise, transgresses against his own light, and misuses those faculties, which were given him . . . (Essays 4.17.24).
Rational creatures, creatures with reason, creatures capable of believing propositions (and of disbelieving and being agnostic with respect to them), say Locke, have duties and obligation with respect to the regulation of their belief or assent. Now the central core of the notion of justification(as the etymology of the term indicates) this: One is justified in doing something or in believing a certain way, if in doing one is innocent of wrong doing and hence not properly subject to blame or censure. You are justified, therefore, if you have violated no duties or obligations, if you have conformed to the relevant requirements, if you are within your rights. To be justified in believing something, then, is to be within your rights in so believing, to be flouting no duty, to be to satisfy your epistemic duties and obligations. This way of thinking of justification has been the dominant way of thinking about justification: And this way of thinking has many important contemporary representatives. Roderick Chisholm, for example (as distinguished an epistemologist as the twentieth century can boast), in his earlier work explicitly explains justification in terms of epistemic duty (Chisholm, 1977).
 The (or, a) main epistemological; questions about religious believe, therefore, has been the question whether or not religious belief in general and theistic belief in particular is justified. And the traditional way to answer that question has been to inquire into the arguments for and against theism. Why this emphasis upon these arguments? An argument is a way of marshalling your propositional evidence-the evidence from other such propositions as likens to believe-for or against a given proposition. And the reason for the emphasis upon argument is the assumption that theistic belief is justified if and only if there is sufficient propositional evidence for it. If there is not’ much by way of propositional evidence for theism, then you are not justified in accepting it. Moreover, if you accept theistic belief without having propositional evidence for it, then you are ging contrary to epistemic duty and are therefore unjustified in accepting it. Thus, W.K. William James, trumpets that ‘it is wrong, always everything upon insufficient evidence’, his is only the most strident in a vast chorus of only insisting that there is an intellectual duty not to believe in God unless you have propositional evidence for that belief. (A few others in the choir: Sigmund Freud, Brand Blanshard, H.H. Price, Bertrand Russell and Michael Scriven.)
 Now how it is that the justification of theistic belief gets identified with there being propositional evidence for it? Justification is a matter of being blameless, of having done one’s duty (in this context, one’s epistemic duty): What, precisely, has this to do with having propositional evidence?
 The answer, once, again, is to be found in Descartes especially Locke. As, justification is the property your beliefs have when, in forming and holding them, you conform to your epistemic duties and obligations. But according to Locke, a central epistemic duty is this: To believe a proposition only to the degree that it is probable with respect to what is certain for you. What propositions are certain for you? First, according to Descartes and Locke, propositions about your own immediate experience, that you have a mild headache, or that it seems to you that you see something red: And second, propositions that are self-evident for you, necessarily true propositions so obvious that you cannot so much as entertain them without seeing that they must be true. (Examples would be simple arithmetical and logical propositions, together with such propositions as that the whole is at least as large as the parts, that red is a colour, and that whatever exists has properties.) Propositions of these two sorts are certain for you, as fort other prepositions. You are justified in believing if and only if when one and only to the degree to which it is probable with respect to what is certain for you. According to Locke, therefore, and according to the whole modern Foundationalist tradition initiated by Locke and Descartes (a tradition that until has recently dominated Western thinking about these topics) there is a duty not to accept a proposition unless it is certain or probable with respect to what is certain.
 In the present context, therefore, the central Lockean assumption is that there is an epistemic duty not to accept theistic belief unless it is probable with respect to what is certain for you: As a consequence, theistic belief is justified only if the existence of God is probable with respect to what is certain. Locke does not argue for his proposition, he simply announces it, and epistemological discussion of theistic belief has for the most part followed hin ion making this assumption. This enables ‘us’ to see why epistemological discussion of theistic belief has tended to focus on the arguments for and against theism: On the view in question, theistic belief is justified only if it is probable with respect to what is certain, and the way to show that it is probable with respect to what it is certain are to give arguments for it from premises that are certain or, are sufficiently probable with respect to what is certain.
 There are at least three important problems with this approach to the epistemology of theistic belief. First, there standards for theistic arguments have traditionally been set absurdly high (and perhaps, part of the responsibility for this must be laid as the door of some who have offered these arguments and claimed that they constitute wholly demonstrative proofs). The idea seems to test. a good theistic argument must start from what is self-evident and proceed majestically by way of self-evidently valid argument forms to its conclusion. It is no wonder that few if any theistic arguments meet that lofty standard  -particularly, in view of the fact that almost no philosophical arguments of any sort meet it. (Think of your favourite philosophical argument: Does it really start from premisses that are self-evident and move by ways of self-evident argument forms to its conclusion?)
 Secondly, attention has ben mostly confined to three theistic arguments: The traditional arguments, cosmological and teleological arguments, but in fact, there are many more good arguments: Arguments from the nature of proper function, and from the nature of propositions, numbers and sets. These are arguments from intentionality, from counterfactual, from the confluence of epistemic reliability with epistemic justification, from reference, simplicity, intuition and love. There are arguments from colours and flavours, from miracles, play and enjoyment, morality, from beauty and from the meaning of life. This is even a theistic argument from the existence of evil.
 But there are a third and deeper problems here. The basic assumption is that theistic belief is justified only if it is or can be shown to be probable with respect to many a body of evidence or proposition  -perhaps, those that are self-evident or about one’s own mental life, but is this assumption true? The idea is that theistic belief is very much like a scientific hypothesis: It is acceptable if and only if there is an appropriate balance of propositional evidence in favour of it. But why believe a thing like that? Perhaps the theory of relativity or the theory of evolution is like that, such a theory has been devised to explain the phenomena and gets all its warrant from its success in so doing. However, other beliefs, e.g., memory beliefs, feelifelt in other minds is not like that, they are not hypothetical at all, and are not accepted because of their explanatory powers. There are instead, the propositions from which one start in attempting to give evidence for a hypothesis. Now, why assume that theistic belief, belief in God, is in this regard more like a scientific hypothesis than like, say, a memory belief? Why think that the justification of theistic belief depends upon the evidential relation of theistic belief to other things one believes? According to Locke and the beginnings of this tradition, it is because there is a duty not to assent to a proposition unless it is probable with respect to what is certain to you, but is there really any such duty? No one has succeeded in showing that, say, belief in other minds or the belief that there has been a past, is probable with respect to what is certain for ‘us’. Suppose it is not: Does it follow that you are living in epistemic sin if you believe that there are other minds? Or a past?
 There are urgent questions about any view according to which one has duties of the sort ‘do not believe ‘p’ unless it is probable with respect to what is certain for you; . First, if this is a duty, is it one to which I can conform? My beliefs are for the most part not within my control: Certainly they are not within my direct control. I believe that there has been a past and that there are other people, even if these beliefs are not probable with respect to what is certain forms (and even if I came to know this) I could not give them up. Whether or not I accept such beliefs are not really up to me at all, For I can no more refrain from believing these things than I can refrain from conforming yo the law of gravity. Second, is there really any reason for thinking I have such a duty? Nearly everyone recognizes such duties as that of not engaging in gratuitous cruelty, taking care of one’s children and one’s aged parents, and the like, but do we also find ourselves recognizing that there is a duty not to believe what is not probable (or, what we cannot see to be probable) with respect to what are certain for ‘us’? It hardly seems so. However, it is hard to see why being justified in believing in God requires that the existence of God be probable with respect to some such body of evidence as the set of propositions certain for you. Perhaps, theistic belief is properly basic, i.e., such that one is perfectly justified in accepting it on the evidential basis of other propositions one believes.
 Taking justification in that original etymological fashion, therefore, there is every reason ton doubt that one is justified in holding theistic belief only inf one is justified in holding theistic belief only if one has evidence for it. Of course, the term ‘justification’ has under-gone various analogical extensions in the of various philosophers, it has been used to name various properties that are different from justification etymologically so-called, but anagogically related to it. In such a way, the term sometimes used to mean propositional evidence: To say that a belief is justified for someone is to saying that he has propositional evidence (or sufficient propositional evidence) for it. So taken, however, the question whether theistic belief is justified loses some of its interest; for it is not clear (given this use)beliefs that are unjustified in that sense. Perhaps, one also does not have propositional evidence for one’s memory beliefs, if so, that would not be a mark against them and would not suggest that there be something wrong holding them.
 Another analogically connected way to think about justification (a way to think about justification by the later Chisholm) is to think of it as simply a relation of fitting between a given proposition and one’s epistemic vase  -which includes the other things one believes, as well as one’s experience. Perhaps tat is the way justification is to be thought of, but then, if it is no longer at all obvious that theistic belief has this property of justification if it seems as a probability with respect to many another body of evidence. Perhaps, again, it is like memory beliefs in this regard.
 To recapitulate: The dominant Western tradition has been inclined to identify warrant with justification, it has been inclined to take the latter in terms of duty and the fulfilment of obligation, and hence to suppose that there is no epistemic duty not to believe in God unless you have good propositional evidence for the existence of God. Epistemological discussion of theistic belief, as a consequence, as concentrated on the propositional evidence for and against theistic belief, i.e., on arguments for and against theistic belief. But there is excellent reason to doubt that there are epistemic duties of the sort the tradition appeals to here.
 And perhaps it was a mistake to identify warrant with justification in the first place. Napoleons have little warrant for him: His problem, however, need not be dereliction of epistemic duty. He is in difficulty, but it is not or necessarily that of failing to fulfill epistemic duty. He may be doing his epistemic best, but he may be doing his epistemic duty in excelsis: But his madness prevents his beliefs from having much by way of warrant. His lack of warrant is not a matter of being unjustified, i.e., failing to fulfill epistemic duty. So warrant and being epistemologically justified by name are not the same things. Another example, suppose (to use the favourite twentieth-century variant of Descartes’ evil demon example) I have been captured by Alpha-Centaurian super-scientists, running a cognitive experiment, they remove my brain, and  keep it alive in some artificial nutrients, and by virtue of their advanced technology induce in me the beliefs I might otherwise have if I were going about my usual business. Then my beliefs would not have much by way of warrant, but would it be because I was failing to do my epistemic duty? Hardly.
 As a result of these and other problems, another, externalist way of thinking about knowledge has appeared in recent epistemology, that a theory of justification is internalized if and only if it requires that all of its factors needed for a belief to be epistemically accessible to that of a person, internal to his cognitive perception, and externalist, if it allows that, at least some of the justifying factors need not be thus accessible, in that they can be external to the believer’ s cognitive Perspectives, beyond his ken. However, epistemologists often use the distinction between internalized and externalist theories of epistemic justification without offering any very explicit explanation.
 Or perhaps the thing to say, is that it has reappeared, for the dominant sprains in epistemology priori to the Enlightenment were really externalist. According to this externalist way of thinking, warrant does not depend upon satisfaction of duty, or upon anything else to which the Knower has special cognitive access (as he does to what is about his own experience and to whether he is trying his best to do his epistemic duty): It depends instead upon factors ‘external’ to the epistemic agent  -such factors as whether his beliefs are produced by reliable cognitive mechanisms, or whether they are produced by epistemic faculties functioning properly in-an appropriate epistemic environment.
 How will we think about the epistemology of theistic belief in more than is less of an externalist way (which is at once both satisfyingly traditional and agreeably up to date)? I think,  that the ontological question whether there is such a person as God is in a way priori to the epistemological question about the warrant of theistic belief. It is natural to think that if in fact we have been created by God, then the cognitive processes that issue in belief in God are indeed realisable belief-producing processes, and if in fact God created ‘us’, then no doubt the cognitive faculties that produce belief in God is functioning properly in an epistemologically congenial environment. On the other hand, if there is no such person as God, if theistic belief is an illusion of some sort, then things are much less clear. Then beliefs in God in of the most of basic ways of wishing that never doubt the production by which unrealistic thinking or another cognitive process not aimed at truth. Thus, it will have little or no warrant. And belief in God on the basis of argument would be like belief in false philosophical theories on the basis of argument: Do such beliefs have warrant? Notwithstanding, the custom of discussing the epistemological questions about theistic belief as if they could be profitably discussed independently of the ontological issue as to whether or not theism is true, is misguided. There two issues are intimately intertwined,
 Nonetheless, the vacancy left, as today and as days before are an awakening and untold story beginning by some sparking conscious paradigm left by science.  That is a central idea by virtue  accredited by its epistemology, where in fact, is that justification and knowledge arising from the proper functioning of our intellectual virtues or faculties in an appropriate environment. This particular yet, peculiar idea is captured in the following criterion for justified belief:
 (J) ‘S’ is justified in believing that ‘p’ if and only if of S’s believing that ‘p’ is the result of S’s intellectual virtues or faculties functioning in appropriate environment.
What is an intellectual virtue or faculty? A virtue or faculty in general is a power or ability or competence to achieve some result. An intellectual virtue or faculty, in the sense intended above, is a power or ability or competence to arrive at truths in a particular field, and to avoid believing falsehoods in that field. Examples of human intellectual virtues are sight, hearing, introspection, memory, deduction and induction. More exactly.
 (V) A mechanism ‘M’ for generating and/or maintaining beliefs is an intellectual virtue if and only if ‘M’‘s’ is a competence to believing true propositions and refrain from false believing propositions within a field of propositions ‘F’, when one is in a set of circumstances ‘C’.
It is required that we specify a particular field of suggestions or its propositional field for ‘M’, since a given cognitive mechanism will be a competence for believing some kind of truths but not others. The faculty of sight, for example, allows ‘us’ to determine the colour of objects, but not the sounds that they associatively make. It is also required that we specify a set of circumstances for ‘M’, since a given cognitive mechanism will be a competence in some circumstances but not others. For example, the faculty of sight allows ‘us’ to determine colours in a well lighten room, but not in a darkened cave or formidable abyss.
 According to the aforementioned formulations, what makes a cognitive mechanism an intellectual virtue is that it is reliable in generating true beliefs than false beliefs in the relevant field and in the relevant circumstances. It is correct to say, therefore, that virtue epistemology is a kind of reliabilism. Whereas, genetic reliabilism maintains that justified belief is belief that results from a reliable cognitive process, virtue epistemology makes a restriction on the kind of process which is allowed. Namely, the cognitive processes that are important for justification and knowledge is those that have their basis in an intellectual virtue.
 Finally, that the concerning mental faculty reliability point to the importance of an appropriate environment. The idea is that cognitive mechanisms might be reliable in some environments but not in others. Consider an example from Alvin Plantinga. On a planet revolving around Alfa Centauri, cats are invisible to human beings. Moreover, Alfa Centaurian cats emit a type of radiation that causes humans to form the belief that there I a dog barking nearby. Suppose now that you are transported to this Alfa Centaurian planet, a cat walks by, and you form the belief that there is a dog barking nearby. Surely you are not justified in believing this. However, the problem here is not with your intellectual faculties, but with your environment. Although your faculties of perception are reliable on earth, yet are unrealisable on the Alga Centaurian planet, which is an inappropriate environment for those faculties.
 The central idea of virtue epistemology, as expressed in (J) above, has a high degree of initial plausibility. By masking the idea of faculties’ cental to the reliability if not by the virtue of epistemology, in that it explains quite neatly to why beliefs are caused by perception and memories are often justified, while beliefs caused by unrealistic and superstition are not. Secondly, the theory gives ‘us’ a basis for answering certain kinds of scepticism. Specifically, we may agree that if we were brains in a vat, or victims of a Cartesian demon, then we would not have knowledge even in those rare cases where our beliefs turned out true. But virtue epistemology explains that what is important for knowledge is toast our faculties are in fact reliable in the environment in which we are. And so we do have knowledge so long as we are in fact, not victims of a Cartesian demon, or brains in a vat. Finally, Plantinga argues that virtue epistemology deals well with Gettier problems. The idea is that Gettier problems give ‘us’ cases of justified belief that is ‘truer by accident’. Virtue epistemology, Plantinga argues, helps ‘us’ to understand what it means for a belief to be true by accident, and provides a basis for saying why such cases are not knowledge. Beliefs are rue by accident when they are caused by otherwise reliable faculties functioning in an inappropriate environment. Plantinga develops this line of reasoning in Plantinga (1988).
 The Humean problem if induction supposes that there is some property ‘A’ pertaining to an observational or experimental situation, and that of ‘A’, some fraction m/n (possibly equal to 1) have also been instances of some logically independent property ‘B’. Suppose further that the background circumstances, have been varied to a substantial degree and that there is no collateral information available concerning the frequency of ‘B’s’ among ‘A’s’ or concerning causal nomological connections between instances of ‘A’ and instances of ‘B’.
 In this situation, an enumerative or instantial inductive inference would move from the premise that m/n of observed ‘A’s’ are ‘B’s’ to the conclusion that approximately m/n of all ‘A’s’ and ‘B’s’. (The usual probability qualification will be assumed to apply to the inference, than being part of the conclusion). Hereabouts the class of ‘A’s’ should be taken to include not only unobservable ‘A’s’ of future ‘A’s’, but also possible or hypothetical ‘a’s’. (An alternative conclusion would concern the probability or likelihood of the very next observed ‘A’ being a ‘B’).
 The traditional or Humean problem of induction, often refereed to simply as ‘the problem of induction’, is the problem of whether and why inferences that fit this schema should be considered rationally acceptable or justified from an epistemic or cognitive standpoint, i.e., whether and why reasoning in this way is likely lead to true claims about the world. Is there any sort of argument or rationale that can be offered for thinking that conclusions reached in this way are likely to be true if the corresponding premiss is true or even that their chances of truth are significantly enhanced?
 Hume’s discussion of this deals explicitly with cases where all observed ‘A’s’ ae ‘B’s’, but his argument applies just as well to the more general casse. His conclusion is entirely negative and sceptical: inductive inferences are not rationally justified, but are instead the result of an essentially a-rational process, custom or habit. Hume challenges the proponent of induction to supply a cogent line of reasoning that leads from an inductive premise to the corresponding conclusion and offers an extremely influential argument in the form of a dilemma, to show that there can be no such reasoning. Such reasoning would, ne argues, have to be either deductively demonstrative reasoning concerning relations of ideas or ‘experimental’, i.e., empirical, reasoning concerning mattes of fact to existence. It cannot be the former, because all demonstrative reasoning relies on the avoidance of contradiction, and it is not a contradiction to suppose that ‘the course of nature may change’, tat an order that was observed in the past will not continue in the future: but it also cannot be the latter, since any empirical argument would appeal to the success of such reasoning in previous experiences, and the justifiability of generalizing from previous experience is precisely what is at issue-s o that any such appeal would be question-begging, so then, there can be no such reasoning.
 An alternative version of the problem may be obtained by formulating it with reference to the so-called Principle of Induction, which says roughly that the future will resemble or, that unobserved cases will reassembly observe cases. An inductive argument may be viewed as enthymematic, with this principle serving as a suppressed premiss, in which case the issue is obviously how such a premise can be justified. Hume’s argument is then that no such justification is possible: The principle cannot be justified speculatively as it is not contradictory to deny it: it cannot be justified by appeal to its having been true in pervious experience without obviously begging te question.
 The predominant recent responses to the problem of induction, at least in the analytic tradition, in effect accept the main conclusion of Hume’s argument, viz. That inductive inferences cannot be justified I the sense of showing that the conclusion of such an inference is likely to be truer if the premise is true, and thus attempt to find some other sort of justification for induction.
 Bearing upon, and if not taken into account the term ‘induction’ is most widely used for any process of reasoning that takes ‘us’ from empirical premises to empirical conclusions supported by the premise, but not deductively entailed by them. Inductive arguments are therefore kinds of amplicative argument, in which something beyond the content of the premises is inferred as probable or supported by them. Induction is, however, commonly distinguished from arguments to theoretical explanations, which share this amplicative character, by being confined to inference in which the conclusion involves the same properties or relations as the premises. The central example is induction by simple enumeration, where from premiss telling that Fa, Fb, Fc. , where a, b, c ~, are all of some kind ‘G’, I t is inferred ‘G’s’ from outside the sample, such as future ‘G’s’ will be ‘F’, or perhaps other person deceive them, children may well infer that everyone is a deceiver. Different but similar inferences are those from the past possession of a property by some object to the same object’s future possession, or from the constancy of some law-like pattern in events, and states of affairs to its future constancy: all objects we know of attract each the with a fore inversely proportional to the square of the distance between them, so perhaps they all do so, an will always do so.
 The rational basis of any inference was challenged by David Hume (1711-76), who believed that induction of nature, and merely reflected a habit or custom of the mind. Hume was not therefore sceptical about the propriety of processes of inducting ion, but sceptical about the tole of reason in either explaining it or justifying it. trying to answer Hume and to show that there is something rationally compelling about the inference is referred to as the problem of induction. It is widely recognized that any rational defence of induction will have to partition well-behaved properties for which the inference is plausible (often called projectable properties) from badly behaved ones for which t is not. It is also recognized that actual inductive habits are more complex than those of simple and science pay attention to such factors as variations within the sample of giving ‘us’ the evidence, the application of ancillary beliefs about the order of nature, and so on. Nevertheless, the fundamental problem remains that any experience shows ‘us’ only events occurring within a very restricted part of the vast spatial temporal order about which we then come to believe things.
 All the same, the classical problem of induction is often phrased in terms of finding some reason to expect that nature is uniform. In Fact, Fiction and Forecast (1954) Goodman showed that we need in addition some reason for preferring some uniformities to others, for without such a selection the uniformity of nature is vacuous. Thus, suppose that all examined emeralds have been green. Uniformity would lead ‘us’ to expect that future emeralds will be green as well. But  now we define a predicate grue: ‘χ’ is trued if and only if ‘χ’ is examined before time ‘T’ and is green, or ‘χ’ is examined after ‘T’ and is blue? Let ’T’ refer to some time around the present. Then if newly examined emeralds are like previous ones in respect of being grue, they will be blue.  We prefer blueness a basis of prediction to gluiness, but why?
Goodman argued that although his new predicate appears to be gerrymandered, and itself involves a reference to a difference, this is just aparohial or language-relative judgement, there being no language-independent standard of similarity to which to appeal. Other philosophers have not been convince by this degree of linguistic relativism. What remains clear that the possibility of these ‘bent’ predicates put a decisive obstacle in face of purely logical and syntactical approaches to problems of ‘confirmation?’.
 Nevertheless, in the potential of change we are to think up to the present time but although virtue epistemology has good initial plausibility, we are faced apart by some substantial objections. The first of an objection, which virtue epistemology face is a version of the generality problem. We may understand the problem more clearly if we were to consider the following criterion for justified belief, which results from our explanation of (J):
 (J ʹ) ‘S’ is justified in believing that ‘p’ if and entirely if.
  (1) there is a field ‘F’ and a set of circumstances ‘C’ such that
    (a) ‘S’ is in ‘C’ with respect to the proposition that ‘p’, and
    (b) ‘S’ is in ‘C’ with respect to the proposition that ‘p’, and
    (e) If ‘S’ were in ‘C’ with respect to a proposition in ‘F’.
    Then ‘S’ would very likely believe correctly with regard to
    that proposition.
The problem arises in how we are to select an appropriate ‘F’ and ‘C’. For given any true belief that ‘p’, we can always come up with a field ‘F’ and a set of circumstances ‘C’, such that ‘S’ is perfectly reliable in ‘F’ and ‘C’.  For any true belief that ‘p’, let ‘F’s’ be the field including only the propositions ‘p’ and ‘not-p’. Let ‘C’ include whatever circumstances there are which causes ‘p’s’ to be true, together with the circumstanced which causes ‘S’ to believe that ‘p’. Clearly, ‘S’ is perfectly reliable with respect to propositions in this field in these circumstances. But we do not want to say that all of S’s true beliefs are justified for ‘S’. And of course, there is an analogous problem in the other direction of generality. For given any belief that ‘p’, we can always specify a field of propositions ‘F’ and a set of circumstances ‘C’, such that ‘p’ is in ‘F’, ‘S’ is in ‘C’, and ‘S’ is not reliable with respect to propositions in ‘F’ in ‘C’.
 Variations of this view have been advanced for both knowledge and justified belief. The first formulation of a reliability account of knowing appeared in a note by F.P. Ramsey (1931), who said that a belief was knowledge if it is true, certain and obtained by a reliable process. P. Unger (1968) suggested that ‘S’ knows that ‘p’ just in case it is not at all accidental that ‘S’ is right about its being the case that ‘p’. D.M. Armstrong (1973) drew an analogy between a thermometer that reliably indicates the temperature and a belief that reliably indicate the truth. Armstrong said that a non-inferential belief qualified as knowledge if the belief has properties that are nominally sufficient for its truth, i.e., guarantee its truth via laws of nature.
 Closely allied to the nomic sufficiency account of knowledge, primarily due to F.I. Dretske (19712, 1981), A.I. Goldman (1976, 1986) and R. Nozick (1981). The core of tis approach is that S’s belief that ‘p’ qualifies as knowledge just in case ‘S’ believes ‘p’ because of reasons that would not obtain unless ‘p’s’ being true, or because of a process or method that would not yield belief in ‘p’ if ‘p’ were not true. For example, ‘S’ would not have his current reasons for believing there is a telephone before him, or would not come to believe this, unless there was a telephone before him. Thus, there is a counterfactual reliable guarantor of the belief’s being true. A variant of the counterfactual approach says that ‘S’ knows that ‘p’ only if there is no ‘relevant alterative’ situation in which ‘p’ is false but ‘S’ would still believe that ‘p’.
 To a better understanding, this interpretation is to mean that the alterative attempt to accommodate any of an opposing strand in our thinking about knowledge one interpretation is an absolute concept, which is to mean that the justification or evidence one must have in order to know a proposition ‘p’ must be sufficient to eliminate all the alternatives to ‘p’ (where an alternative to a proposition ‘p’ is a proposition incompatible with ‘p’). That is, one’s justification or evidence for ‘p’ must be sufficient fort one to know that every alternative to ‘p’ is false. These elements of our thinking about knowledge are exploited by sceptical argument. These arguments call our attention to alternatives that our evidence cannot eliminate. For example, (Dretske, 1970), when we are at the zoo. We might claim to know that we see a zebra on the basis of certain visual evidence, namely a zebra-like appearance. The sceptic inquires how we know that we are not seeing a clearly disguised mule. While we do have some evidence against the likelihood of such a deception, intuitively it is not strong enough for ‘us’ to know that we are not so deceived. By pointing out alternatives of this nature that cannot eliminate, as well as others with more general application (dreams, hallucinations, etc.), the sceptic appears to show that this requirement that our evidence eliminate every alternative is seldom, if ever, met.
 The above considerations show that virtue epistemology must say more about the selection of relevant fields and sets of circumstances. Establishing addresses the generality problem by introducing the concept of a design plan for our intellectual faculties. Relevant specifications for fields and sets of circumstances are determined by this plan. One might object that this approach requires the problematic assumption of a Designer of the design plan. But Plantinga disagrees on two counts: He does not think that the assumption is needed, or that it would be problematic. Plantinga discusses relevant material in Plantinga (1986, 1987 and 1988). Ernest Sosa addresses the generality problem by introducing the concept of an epistemic perspective. In order to have reflective knowledge, ‘S’ must have a true grasp of the reliability of her faculties, this grasp being itself provided by a ‘faculty of faculties’. Relevant specifications of an ‘F’ and ‘C’ are determined by this perspective. Alternatively, Sosa has suggested that relevant specifications are determined by the purposes of the epistemic community. The idea is that fields and sets of circumstances are determined by their place in useful generalizations about epistemic agents and their abilities to act as reliable-information sharers.
 The second objection which virtue epistemology faces are that (J) and
(J ʹ) are too strong. It is possible for ‘S’ to be justified in believing that ‘p’, even when S’s intellectual faculties are largely unreliable. Suppose, for example, that Jane’s beliefs about the world around her are true. It is clear that in this case Jane’s faculties of perception are almost wholly unreliable. But we would not want to say that none of Jane’s perceptual beliefs are justified. If Jane believes that there is a tree in her yard, and she vases the belief on the usual tree-like experience, then it seems that she is as justified as we would be regarded a substitutable belief.
 Sosa addresses the current problem by arguing that justification is relative to an environment ‘E’. Accordingly, ‘S’ is justified in believing that ‘p’ relative to ‘E’, if and only if S’s faculties would be reliable in ‘E’. Note that on this account, ‘S’ need not actually be in ‘E’ in order for ‘S’ to be justified in believing some proposition relative to ‘E’. This allows Soda to conclude that Jane has justified belief in the above case. For Jane is justified in her perceptual beliefs relative to our environment, although she is not justified in those beliefs relative to the environment in which they have actualized her.
 We have earlier made mention about analyticity, but the true story of analyticity is surprising in many ways. Contrary to received opinion, it was the empiricist Locke rather than the rationalist Kant who had the better information account of this type or deductive proposition. Frége and Rudolf Carnap (1891-1970) A German logician positivist whose first major works was ‘Der logische Aufbau der Welt’ (1926, translates, as ‘The Logical Structure of the World,’ 1967). Carnap pursued the enterprise of clarifying the structures of mathematics and scientific language (the only legitimate task for scientific philosophy) in ‘Logische Syntax der Sprache’ (1934, trans. As ‘The Logical Syntax of Language,’ 1937). Yet, refinements continued with ‘Meaning and Necessity’ (1947), while a general losing of the original ideal of reduction culminated in the great ‘Logical Foundations of Probability’ and the most importantly single work of ‘confirmation theory’ in 1950. Other works concern the structure of physics and the concept of entropy.
 Both, Frége and Carnap, represented as analyticity’s best friends in this century, did as much to undermine it as its worst enemies. Quine (1908-) whose early work was on mathematical logic, and issued in ‘A System of Logistic’ (1934), ‘Mathematical Logic’ (1940) and ‘Methods of Logic’ (1950) it was with this collection of papers a ‘Logical Point of View’ (1953) that his philosophical importance became widely recognized, also, Putman (1926-) his concern in the later period has largely been to deny any serious asymmetry between truth and knowledge as it is obtained in natural science, and as it is obtained in morals and even theology. Books include ‘Philosophy of logic’ (1971), ‘Representation and Reality’ (1988) and ‘Renewing Philosophy (1992). Collections of his papers include ‘Mathematics, Master, sand Method’ (1975), ‘Mind, Language, and Reality’ (1975), and ‘Realism and Reason (1983). Both of which represented as having refuted the analytic/synthetic distinction, not only did no such thing, but, in fact, contributed significantly to undoing the damage done by Frége and Carnap. Finally, the epistemological significance of the distinctions is nothing like what it is commonly taken to be.
 Locke’s account of an analyticity proposition as, for its time, everything that a succinct account of analyticity should be (Locke, 1924, pp. 306-8) he distinguished two kinds of analytic propositions, identified propositions in which we affirm the said terms if itself, e.g., ‘Roses are roses’, and predicative propositions in which ‘a part of the complex idea is predicated of the name of the whole’, e.g., ‘Roses are flowers’ (pp. 306-7). Locke calls such sentences ‘trifling’ because a speaker who uses them ‘trifles with words’. A synthetic sentence, in contrast, such as a mathematical theorem, states ‘a truth and conveys with its informative real knowledge’. Correspondingly, Locke distinguishes two kinds of ‘ necessary consequences’, analytic entailment where validity depends on the literal containment of the conclusions in the premiss and synthetic entailments where it does not. (Locke did not originate this concept-containment notion of analyticity. It is discussions by Arnaud and Nicole, and it is safe to say it has been around for a very long time (Arnaud, 1964).
 Kant’s account of analyticity, which received opinion tells ‘us’ is the consummate formulation of this notion in modern philosophy, is actually a step backward. What is valid in his account is not novel, and what is novel is not valid. Kant presents Locke’s account of concept-containment analyticity, but introduces certain alien features, the most important being his characterizations of most important being his characterization of analytic propositions as propositions whose denials are logical contradictions (Kant, 1783). This characterization suggests that analytic propositions based on Locke’s part-whole relation or Kant’s explicative copula are a species of logical truth. But the containment of the predicate concept in the subject concept in sentences like ‘Bachelors are unmarried’ is a different relation from containment of the consequent in the antecedent in a sentence like ‘If John is a bachelor, then John is a bachelor or Mary read Kant’s Critique’. The former is literal containment whereas, the latter are, in general, not. Talk of the ‘containment’ of the consequent of a logical truth in the metaphorical, a way of saying ‘logically derivable’.
 Kant’s conflation of concept containment with logical containment caused him to overlook the issue of whether logical truths are synthetically deductive and the problem of how he can say mathematical truths are synthetically deductive when they cannot be denied without contradiction. Historically. , the conflation set the stage for the disappearance of the Lockean notion. Frége, whom received opinion portrays as second only to Kant among the champions of analyticity, and Carnap, who it portrays as just behind Frége, was jointly responsible for the appearance of concept-containment analyticity.
 Frége was clear about the difference between concept containment and logical containment, expressing it as like the difference between the containment of ‘beams in a house’ the containment of a ‘plant in the seed’ (Frége, 1853). But he found the former, as Kant formulated it, defective in three ways: It explains analyticity in psychological terms, it does not cover all cases of analytic propositions, and, perhaps, most important for Frége’s logicism, its notion of containment is ‘unfruitful’ as a definition; mechanisms in logic and mathematics (Frége, 1853). In an insidious containment between the two notions of containment, Frége observes that with logical containment ‘we are not simply talking out of the box again what we have just put inti it’. This definition makes logical containment the basic notion. Analyticity becomes a special case of logical truth, and, even in this special case, the definitions employ the power of definition in logic and mathematics than mere concept combination.
 Carnap, attempting to overcome what he saw a shortcoming in Frége’s account of analyticity, took the remaining step necessary to do away explicitly with Lockean-Kantian analyticity. As Carnap saw things, it was a shortcoming of Frége’s explanation that it seems to suggest that definitional relations underlying analytic propositions can be extra-logic in some sense, say, in resting on linguistic synonymy. To Carnap, this represented a failure to achieve a uniform formal treatment of analytic propositions and left ‘us’ with a dubious distinction between logical and extra-logical vocabulary. Hence, he eliminated the reference to definitions in Frége’s  of analyticity by introducing ‘meaning postulates’, e.g., statements such as (∀χ) (χ is a bachelor-is unmarried) (Carnap, 1965). Like standard logical postulate on which they were modelled, meaning postulates express nothing more than constrains on the admissible models with respect to which sentences and deductions are evaluated for truth and validity. Thus, despite their name, its asymptomatic-balance having to pustulate itself by that in what it holds on to not more than to do with meaning than any value-added statements expressing an indispensable truth. In defining analytic propositions as consequences of (an explained set of) logical laws, Carnap explicitly removed the one place in Frége’s explanation where there might be room for concept containment and with it, the last trace of Locke’s distinction between semantic and other ‘necessary consequences’.
 Quine, the staunchest critic of analyticity of our time, performed an invaluable service on its behalf-although, one that has come almost completely unappreciated. Quine made two devastating criticism of Carnap’s meaning postulate approach that expose it as both irrelevant and vacuous. It is irrelevant because, in using particular words of a language, meaning postulates fail to explicate analyticity for sentences and languages generally, that is, they do not define it for variables ‘S’ and ‘L’ (Quine, 1953). It is vacuous because, although meaning postulates tell ‘us’ what sentences are to count as analytic, they do not tell ‘us’ what it is for them to be analytic.
 Received opinion gas it that Quine did much more than refute the analytic/synthetic distinction as Carnap tried to draw it. Received opinion has that Quine demonstrated there is no distinction, however, anyone might try to draw it. Nut this, too, is incorrect. To argue for this stronger conclusion, Quine had to show that there is no way to draw the distinction outside logic, in particular theory in linguistic corresponding to Carnap’s, Quine’s argument had to take an entirely different form. Some inherent feature of linguistics had to be exploited in showing that no theory in this science can deliver the distinction. But the feature Quine chose was a principle of operationalist methodology characteristic of the school of Bloomfieldian linguistics. Quine succeeds in showing that meaning cannot be made objective sense of in linguistics. If making sense of a linguistic concept requires, as that school claims, operationally defining it in terms of substitution procedures that employ only concepts unrelated to that linguistic concept. But Chomsky’s revolution in linguistics replaced the Bloomfieldian taxonomic model of grammars with the hypothetico-deductive model of generative linguistics, and, as a consequence, such operational definition was removed as the standard for concepts in linguistics. The standard of theoretical definition that replaced it was far more liberal, allowing the members of as family of linguistic concepts to be defied with respect to one another within a set of axioms that state their systematic interconnections  -the entire system being judged by whether its consequences are confirmed by the linguistic facts. Quine’s argument does not even address theories of meaning based on this hypothetico-deductive model (Katz, 1988 and 1990).
 Putman, the other staunch critic of analyticity, performed a service on behalf of analyticity fully on a par with, and complementary to Quine’s, whereas, Quine refuted Carnap’s formalization of Frége’s conception of analyticity, Putman refuted this very conception itself. Putman put an end to the entire attempt, initiated by Fridge and completed by Carnap, to construe analyticity as a logical concept (Putman, 1962, 1970, 1975a).
 However, as with Quine, received opinion has it that Putman did much more. Putman in credited with having devised science fiction cases, from the robot cat case to the twin earth cases, that are counter examples to the traditional theory of meaning. Again, received opinion is incorrect. These cases are only counter examples to Frége’s version of the traditional theory of meaning. Frége’s version claims both (1) that senses determines reference, and (2) that there are instances of analyticity, say, typified by ‘cats are animals’, and of synonymy, say typified by ‘water’ in English and ‘water’ in twin earth English. Given (1) and (2), what we call ‘cats’ could not be non-animals and what we call ‘water’ could not differ from what the earthier twin called ‘water’. But, as Putman’s cases show, what we call ‘cats’ could be Martian robots and what they call ‘water’ could be something other than H2O Hence, the cases are counter examples to Frége’s version of the theory.
 Putman himself takes these examples to refute the traditional theory of meaning per se, because he thinks other versions must also subscribe to both (1) and. (2). He was mistaken in the case of (1). Frége’s theory entails (1) because it defines the sense of an expression as the mode of determination of its referent (Fridge, 1952, pp. 56-78). But sense does not have to be defined this way, or in any way that entails (1). / it can be defined as (D).
    (D) Sense is that aspect of the grammatical structure of expressions and sentences responsible for their having sense properties and relations like meaningfulness, ambiguity, antonymy, synonymy, redundancy, analyticity and analytic entailment. (Katz, 1972 & 1990).
(Note that this use of sense properties and relations is no more circular than the use of logical properties and relations to define logical form, for example, as that aspect of grammatical structure of sentences on which their logical implications depend.)
 (D) makes senses internal to the grammar of a language and reference an external; matter of language use  -typically involving extra-linguistic beliefs, Therefore, (D) cuts the strong connection between sense and reference expressed in (1), so that there is no inference from the modal fact that ‘cats’ refer to robots to the conclusion that ‘Cats are animals’ are not analytic. Likewise, there is no inference from ‘water’ referring to different substances on earth and twin earth to the conclusion that our word and theirs are not synonymous. Putman’s science fiction cases do not apply to a version of the traditional theory of meaning based on (D).
 The success of Putman and Quine’s criticism in application to Fridge and Carnap’s theory of meaning together with their failure in application to a theory in linguistics based on (D) creates the option of overcoming the shortcomings of the Lockean-Kantian notion of analyticity without switching to a logical notion. this option was explored in the 1960s and 1970s in the course of developing a theory of meaning modelled on the hypothetico-deductive paradigm for grammars introduced in the Chomskyan revolution (Katz, 1972).
 This theory automatically avoids Frége’s criticism of the psychological formulation of Kant’s definition because, as an explication of a grammatical notion within linguistics, it is stated as a formal account of the structure of expressions and sentences. The theory also avoids Frége’s criticism that concept-containment analyticity is not ‘fruitful’ enough to encompass truths of logic and mathematics. The criticism rests on the dubious assumption, parts of Frége’s logicism, that analyticity ‘should’ encompass them, (Benacerraf, 1981). But in linguistics where the only concern is the scientific truth about natural concept-containment analyticity encompass truths of logic and mathematics. Moreover, since we are seeking the scientific truth about trifling propositions in natural language, we will eschew relations from logic and mathematics that are too fruitful for the description of such propositions. This is not to deny that we want a notion of necessary truth that goes beyond the trifling, but only to deny that, that notion is the notion of analyticity in natural language.
 The remaining Frégean criticism points to a genuine incompleteness of the traditional account of analyticity. There are analytic relational sentences, for example, Jane walks with those with whom she strolls, ’Jack kills those he himself has murdered’, etc., and analytic entailment with existential conclusions, for example, ‘I think’, therefore ‘I exist’. The containment in these sentences is just as literal as that in an analytic subject-predicate sentence like ‘Bachelors are unmarried’, such are shown to have a theory of meaning construed as a hypothetico-deductive systemisations of sense as defined in (D) overcoming the incompleteness of the traditional account in the case of such relational sentences.
 Such a theory of meaning makes the principal concern of semantics the explanation of sense properties and relations like synonymy, an antonymy, redundancy, analyticity, ambiguity, etc. Furthermore, it makes grammatical structure, specifically, senses structure, the basis for explaining them. This leads directly to the discovery of a new level of grammatical structure, and this, in turn, makes possible a proper definition of analyticity. To see this, consider two simple examples. It is a semantic fact that ‘a male bachelor’ is redundant and that ‘single person’ is synonymous with ‘woman who never married; . In the case of the redundancy, we have to explain the fact that the sense of the modifier ‘male’ is already contained in the sense of its head ‘bachelor’. In the case of the synonymy, we have to explain the fact that the sense of ‘sinister’ is identical to the sense of ‘woman who never married’ (compositionally formed from the senses of ‘woman’, ‘never’ and ‘married’). But is so fas as such facts concern relations involving the components of the senses of ‘bachelor’ and ‘spinster’ and is in as far as these words are syntactic simple, there must be a level of grammatical structure at which syntactic simple are semantically complex. This, in brief, is the route by which we arrive a level of ‘decompositional semantic structure; that is the locus of sense structures masked by syntactically simple words.
 Discovery of this new level of grammatical structure was followed by attemptive efforts as afforded to represent the structure of the sense’s finds there. Without going into detail of sense representations, it is clear that, once we have the notion of decompositional representation, we can see how to generalize Locke and Kant’s informal, subject-predicate account of analyticity to cover relational analytic sentences. Let a simple sentence ‘S’ consisted of a -place predicate ‘P’ with terms T1 . . . , . Tn occupying its argument places. Then:
    The analysis in case, first, S has a term T1 that consists of a place predicate Q (m > n or m = n) with terms occupying its argument places, and second, P is contained in Q and, for each term TJ . . . . T1 + I, . . . . , Tn, TJ is contained in the term of Q that occupies the argument place in Q corresponding to the argument place occupied by TJ in P. (Katz, 1972)
To see how (A) works, suppose that ‘stroll’ in ‘Jane walks with those whom she strolls’ is decompositionally represented as having the same sense as ‘walk idly and in a leisurely way’. The sentence is analytic by (A) because the predicate ‘stroll’ (the sense of ‘stroll) and the term ‘Jane’ * the sense of ‘Jane’ associated with the predicate ‘walk’) is contained in the term ‘Jane’ (the sense of ‘she herself’ associated with the predicate ‘stroll’). The containment in the case of the other terms is automatic.
 The fact that (A) itself makes no reference to logical operators or logical laws indicate that analyticity for subject-predicate sentences can be extended to simple relational sentences without treating analytic sentences as instances of logical truths. Further, the source of the incompleteness is no longer explained, as Fridge explained it, as the absence of ‘fruitful’ logical apparatus, but is now explained as mistakenly treating what is only a special case of analyticity as if it were the general case. The inclusion of the predicate in the subject is the special case (where n = 1) of the general case of the inclusion of an–place predicate (and its terms) in one of its terms. Noting that the defects, by which, Quine complained of in connection with Carnap’s meaning-postulated explication are absent in (A). (A) contains no words from a natural language. It explicitly uses variable ‘S’ and variable ‘L’ because it is a definition in linguistic theory. Moreover, (A) tell ‘us’ what property is in virtue of which a sentence is analytic, namely, redundant predication, that is, the predication structure of an analytic sentence is already found in the content of its term structure.
 Received opinion has been anti-Lockean in holding that necessary consequences in logic and language belong to one and the same species. This seems wrong because the property of redundant predication provides a non-logic explanation of why true statements made in the literal use of analytic sentences are necessarily true. Since the property ensures that the objects of the predication in the use of an analytic sentence are chosen on the basis of the features to be predicated of them, the truth-conditions of the statement are automatically satisfied once its terms take on reference. The difference between such a linguistic source of necessity and the logical and
mathematical sources vindicate Locke’s distinction between two kinds of ‘necessary consequence’.
 Received opinion concerning analyticity contains another mistake. This is the idea that analyticity is inimical to science, in part, the idea developed as a reaction to certain dubious uses of analyticity such as Frége’s attempt to establish logicism and Schlick’s, Ayer’s and other logical; postivists attempt to deflate claims to metaphysical knowledge by showing that alleged deductive truths are merely empty analytic truths (Schlick, 1948, and Ayer, 1946). In part, it developed as also a response to a number of cases where alleged analytic, and hence, necessary truths, e.g., the law of excluded a seeming next-to-last subsequent to have been taken as open to revision, such cases convinced philosophers like Quine and Putnam that the analytic/synthetic distinction is an obstacle to scientific progress.
 The problem, if there is, one is one is not analyticity in the concept-containment sense, but the conflation of it with analyticity in the logical sense. This made it seem as if there is a single concept of analyticity that can serve as the grounds for a wide range of deductive truths. But, just as there are two analytic/synthetic distinctions, so there are two concepts of concept. The narrow Lockean/Kantian distinction is based on a narrow notion of expressions on which concepts are senses of expressions in the language. The broad Frégean/Carnap distinction is based on a broad notion of concept on which concepts are conceptions  -often scientific one about the nature of the referent (s) of expressions (Katz, 1972) and curiously Putman, 1981). Conflation of these two notions of concepts produced the illusion of a single concept with the content of philosophical, logical and mathematical conceptions, but with the status of linguistic concepts. This encouraged philosophers to think that they were in possession of concepts with the contentual representation to express substantive philosophical claims, e.g., such as Fridge, Schlick and Ayer’s, . . . and so on, and with a status that trivializes the task of justifying them by requiring only linguistic grounds for the deductive propositions in question.
 Finally, there is an important epistemological implication of separating the broad and narrowed notions of analyticity. Fridge and Carnap took the broad notion of analyticity to provide foundations for necessary and a priority, and, hence, for some form of rationalism, and nearly all rationalistically inclined analytic philosophers followed them in this. Thus, when Quine dispatched the Frége-Carnap position on analyticity, it was widely believed that necessary, as a priority, and rationalism had also been despatched, and, as a consequence. Quine had ushered in an ‘empiricism without dogmas’ and ‘naturalized epistemology’. But given there is still a notion of analyticity that enables ‘us’ to pose the problem of how necessary, synthetic deductive knowledge is possible (moreover, one whose narrowness makes logical and mathematical knowledge part of the problem), Quine did not under-cut the foundations of rationalism. Hence, a serious reappraisal of the new empiricism and naturalized epistemology is, to any the least, is  very much in order (Katz, 1990).
 In some areas of philosophy and sometimes in things that are less than important we are to find in the deductively/inductive distinction in which has been applied to a wide range of objects, including concepts, propositions, truths and knowledge. Our primary concern will, however, be with the epistemic distinction between deductive and inductive knowledge. The most common way of marking the distinction is by reference to Kant’s claim that deductive knowledge is absolutely independent of all experience. It is generally agreed that S’s knowledge that ‘p’ is independent of experience just in case S’s belief that ‘p’ is justified independently of experience. Some authors (Butchvarov, 1970, and Pollock, 1974) are, however, in finding this negative characterization of deductive unsatisfactory knowledge and have opted for providing a positive characterisation in terms of the type of justification on which such knowledge is dependent. Finally, others (Putman, 1983 and Chisholm, 1989) have attempted to mark the distinction by introducing concepts such as necessity and rational unrevisability than in terms of the type of justification relevant to deductive knowledge.
 One who characterizes deductive knowledge in terms of justification that is independent of experience is faced with the task of articulating the relevant sense of experience, and proponents of the deductive ly cites ‘intuition’ or ‘intuitive apprehension’ as the source of deductive justification. Furthermore, they maintain that these terms refer to a distinctive type of experience that is both common and familiar to most individuals. Hence, there is a broad sense of experience in which deductive justification is dependent of experience. An initially attractive strategy is to suggest that theoretical justification must be independent of sense experience. But this account is too narrow since memory, for example, is not a form of sense experience, but justification based on memory is presumably not deductive. There appear to remain only two options: Provide a general characterization of the relevant sense of experience or enumerates those sources that are experiential. General characterizations of experience often maintain that experience provides information specific to the actual world while non-experiential sources provide information about all possible worlds. This approach, however, reduces the concept of non-experiential justification to the concept of being justified in believing a necessary truth. Accounts by enumeration have two problems (1) there is some controversy about which sources to include in the list, and (2) there is no guarantee that the list is complete. It is generally agreed that perception and memory should be included. Introspection, however, is problematic, and beliefs about one’s conscious states and about the manner in which one is appeared to are plausible regarded as experientially justified. Yet, some, such as Pap (1958), maintain that experiments in imagination are the source of deductive justification. Even if this contention is rejected and deductive justification is characterized as justification independent of the evidence of perception, memory and introspection, it remains possible that there are other sources of justification. If it should be the case that clairvoyance, for example, is a source of justified beliefs, such beliefs would be justified deductively on the enumerative account.
 The most common approach to offering a positive characterization of deductive justification is to maintain that in the case of basic deductive propositions, understanding the proposition is sufficient to justify one in believing that it is true. This approach faces two pressing issues. What is it to understand a proposition in the manner that suffices for justification? Proponents of the approach typically distinguish understanding the words used to express a proposition from apprehending the proposition itself and maintain that it is the latter which are relevant to deductive justification. But this move simply shifts the problem to that of specifying what it is to apprehend a proposition. Without a solution to this problem, it is difficult, if possible, to evaluate the account since one cannot be sure that the account since on cannot be sure that the requisite sense of apprehension does not justify paradigmatic inductive propositions as well. Even less is said about the manner in which apprehending a proposition justifies one in believing that it is true. Proponents are often content with the bald assertions that one who understands a basic deductive proposition can thereby ‘see’ that it is true. But what requires explanation is how understanding a proposition enable one to see that it is true.
 Difficulties in characterizing deductive justification in a term either of independence from experience or of its source have led, out-of-the-ordinary to present the concept of necessity into their accounts, although this appeal takes various forms. Some have employed it as a necessary condition for deductive justification, others have employed it as a sufficient condition, while still others have employed it as both. In claiming that necessity is a criterion of the deductive. Kant held that necessity is a sufficient condition for deductive justification. This claim, however, needs further clarification. There are three theses regarding the relationship between the theoretically and the necessary that can be distinguished: (I) if ‘p’ is a necessary proposition and ‘S’ is justified in believing that ‘p’ is necessary, then S’s justification is deductive: (ii) If ‘p’ is a necessary proposition and ‘S’ is justified in believing that ‘p’ is necessarily true, then S’s justification is deductive: And (iii) If ‘p’ is a necessary proposition and ‘S’ is justified in believing that ‘p’, then S’s justification is deductive. For example, many proponents of deductive contend that all knowledge of a necessary proposition is deductive. (2) and (3) have the shortcoming of setting by stipulation the issue of whether inductive knowledge of necessary propositions is possible. (I) does not have this shortcoming since the recent examples offered in support of this claim by Kriple (1980) and others have been cases where it is alleged that knowledge of the ‘truth value’ of necessary propositions is knowable inductive. (I) has the shortcoming, however, of either ruling out the possibility of being justified in believing that a proposition is necessary on the basis of testimony or else sanctioning such justification as deductive. (ii) and (iii), of course, suffer from an analogous problem. These problems are symptomatic of a general shortcoming of the approach: It attempts to provide a sufficient condition for deductive justification solely in terms of the modal status of the proposition believed without making reference to the manner in which it is justified. This shortcoming, however, can be avoided by incorporating necessity as a necessary but not sufficient condition for a prior justification as, for example, in Chisholm (1989). Here there are two theses that must be distinguished: (1) If ‘S’ is justified deductively in believing that ‘p’, then ‘p’ is necessarily true.  (2) If ‘S’ is justified deductively in believing that ‘p’. Then ‘p’ is a necessary proposition. (1) and (2), however, allows this possibility. A further problem with both (1) and (2) is that it is not clear whether they permit deductively justified beliefs about the modal status of a proposition. For they require that in order for ‘S’ to be justified deductively in believing that ‘p’ is a necessary preposition it must be necessary that ‘p’ is a necessary proposition. But the status of iterated modal propositions is controversial. Finally, (1) and (2) both preclude by stipulation the position advanced by Kripke (1980) and Kitcher (1980) that there is deductive knowledge of contingent propositions.
 The concept of rational unrevisability has also been invoked to characterize deductive justification. The precise sense of rational unrevisability has been presented in different ways. Putnam (1983) takes rational unrevisability to be both a necessary and sufficient condition for deductive justification while Kitcher (1980) takes it to be only a necessary condition. There are also two different senses of rational unrevisability that have been associated with the deductive (I) a proposition is weakly unreviable just in case it is rationally unrevisable in light of any future ‘experiential’ evidence, and (II) a proposition is strongly unrevisable just in case it is rationally unrevisable in light of any future evidence. Let us consider the plausibility of requiring either form of rational unrevisability as a necessary condition for deductive justification. The view that a proposition is justified deductive only if it is strongly unrevisable entails that if a non-experiential source of justified beliefs is fallible but self-correcting, it is not a deductive source of justification. Casullo (1988) has argued that it vis implausible to maintain that a proposition that is justified non-experientially is ‘not’ justified deductively merely because it is revisable in light of further non-experiential evidence. The view that a proposition is justified deductively only if it is, weakly unrevisable is not open to this objection since it excludes only recision in light of experiential evidence. It does, however, face a different problem. To maintain that S’s justified belief that ‘p’ is justified deductively is to make a claim about the type of evidence that justifies ‘S’ in believing that ‘p’. On the other hand, to maintain that S’s justified belief that ‘p’ is rationally revisable in light of experiential evidence is to make a claim about the type of evidence that can defeat S’s justification for believing that ‘p’ that a claim about the type of evidence that justifies ‘S’ in believing that ‘p’. Hence, it has been argued by Edidin (1984) and Casullo (1988) that to hold that a belief is justified deductively only if it is weakly unrevisable is either to confuse supporting evidence with defeating evidence or to endorse some implausible this about the relationship between the two such as that if evidence of the sort as the kind ‘A’ can defeat the justification conferred on S’s belief that ‘p’ by evidence of kind ‘B’ then S’s justification for believing that ‘p’ is based on evidence of kind ‘A’.
 The most influential idea in the theory of meaning in the past hundred years is the thesis that the meaning of an indicative sentence is given by its truth-conditions. On this conception, to understand a sentence is to know its truth-conditions. The conception was first clearly formulated by Fridge, was developed in a distinctive way by the early Wittgenstein, and is a leading idea of Donald Herbert Davidson (1917-), who is also known for rejection of the idea of as conceptual scheme, thought of as something peculiar to one language or one way of looking at the world, arguing that where the possibility of translation stops so dopes the coherence of the idea that there is anything to translate. His [papers are collected in the ‘Essays on Actions and Events’ (1980) and ‘Inquiries into Truth and Interpretation’ (1983). However, the conception has remained so central that those who offer opposing theories characteristically define their position by reference to it.
 Wittgenstein’s main achievement is a uniform theory of language that yields an explanation of logical truth. A factual sentence achieves sense by dividing the possibilities exhaustively into two groups, those that would make it true and those that would make it false. A truth of logic does not divide the possibilities but comes out true in all of them. It, therefore, lacks sense and says nothing, but it is not nonsense. It is a self-cancellation of sense, necessarily true because it is a tautology, the limiting case of factual discourse, like the figure ‘0' in mathematics. Language takes many forms and even factual discourse does not consist entirely of sentences like ‘The fork is placed to the left of the knife’. However, the first thing that he gave up was the idea that this sentence itself needed further analysis into basic sentences mentioning simple objects with no internal structure. He was to concede, that a descriptive word will often get its meaning partly from its place in a system, and he applied this idea to colour-words, arguing that the essential relations between different colours do not indicate that each colour has an internal structure that needs to be taken apart. On the contrary, analysis of our colour-words would only reveal the same pattern-ranges of incompatible properties-recurring at every level, because that is how we carve up the world.
 Indeed, it may even be the case that of our ordinary language is created by moves that we ourselves make. If so, the philosophy of language will lead into the connection between the meaning of a word and the applications of it that its users intend to make. There is also an obvious need for people to understand each other’s meanings of their words. There are many links between the philosophy of language and the philosophy of mind and it is not surprising that the impersonal examination of language in the ‘Tractatus: was replaced by a very different, anthropocentric treatment in ‘Philosophical Investigations?’
 If the logic of our language is created by moves that we ourselves make, various kinds of realisms are threatened. First, the way in which our descriptive language carves up the world will not be forces on ‘us’ by the natures of things, and the rules for the application of our words, which feel the external constraints, will really come from within ‘us’. That is a concession to nominalism that is, perhaps, readily made. The idea that logical and mathematical necessity is also generated by what we ourselves accomplish what is more paradoxical. Yet, that is the conclusion of Wittengenstein (1956) and (1976), and here his anthropocentricism has carried less conviction. However, a paradox is not sure of error and it is possible that what is needed here is a more sophisticated concept of objectivity than Platonism provides.
 In his later work Wittgenstein brings the great problem of philosophy down to earth and traces them to very ordinary origins. His examination of the concept of ‘following a rule’ takes him back to a fundamental question about counting things and sorting them into types: ‘What qualifies as doing the same again? Of a courser, this question as an inconsequential fundamental and would suggest that we forget it and get on with the subject. But Wittgenstein’s question is not so easily dismissed. It has the naive profundity of questions that children ask when they are first taught a new subject. Such questions remain unanswered without detriment to their learning, but they point the only way to complete understanding of what is learned.
 It is, nevertheless, the meaning of a complex expression in a function of the meaning of its constituents, that is, indeed, that it is just a statement of what it is for an expression to be semantically complex. It is one of the initial attractions of the conception of meaning as truths-conditions that it permits a smooth and satisfying account of the way in which the meaning of a complex expression is a dynamic function of the meaning of its constituents. On the truth-conditional conception, to give the meaning of an expression is to state the contribution it makes to the truth-conditions of sentences in which it occurs. for singular terms-proper names, indexicals, and certain pronoun’s  -this is done by stating the reference of the term in question.
 The truth condition of a statement is the condition the world must meet if the statement is to be true. To know this condition is equivalent to knowing the meaning of the statement. Although, this sounds as if it gives a solid anchorage for meaning, some of the security disappears when it turns out that the truth condition can only be defined by repeating the very same statement, the truth condition of ‘snow is white’ is that snow is white, the truth condition of ‘Britain would have capitulated had Hitler invaded’ is that Britain would halve capitulated had Hitler invaded. It is disputed whether this element of running-on-the-spot disqualifies truth conditions from playing the central role in a substantive theory of meaning. Truth-conditional theories of meaning are sometimes opposed by the view that to know the meaning of a statement is to be able to users it in a network of inferences.
 On the truth-conditional conception, to give the meaning of expressions is to state the contributive function it makes to the dynamic function of sentences in which it occurs. For singular terms-proper names, and certain pronouns, as well are indexicals-this is done by stating the reference of the term in question. For predicates, it is done either by stating the conditions under which the predicate is true of arbitrary objects, or by stating the conditions under which arbitrary atomic sentence containing it is true. The meaning of a sentence-forming operator is given by stating its distributive contribution to the truth-conditions of a complete sentence, as a function of the semantic values of the sentences on which it operates. For an extremely simple, but nonetheless, it is a structured language, we can state the contributions various expressions make to truth conditions as follows:
  A1: The referent of ‘London’ is London.
  A2: The referent of ‘Paris’ is Paris.
  A3: Any sentence of the form ‘a is beautiful’ is true if and only if the referent of ‘a’ is beautiful.
  A4: Any sentence of the form ‘a is larger than b’ is true if and only if the referent of ‘a’ is larger than the referent of ‘b’.
  A5: Any sentence of the form ‘It is not the case that A’ is true if and only if it is not the case that ‘A’ is true.
  A6: Any sentence of the form ‘A and B’ are true if and only is ‘A’ is true and ‘B’ is true.
The principle’s A2-A6 form a simple theory of truth for a fragment of English. In this theory, it is possible to derive these consequences: That ‘Paris is beautiful’ is true if and only if Paris is beautiful (from A2 and A3), which ‘London is larger than Paris and it is not the cases that London is beautiful’ is true if and only if London is larger than Paris and it is not the case that London is beautiful (from A1-As): And in general, for any sentence ‘A’ of this simple language, we can derive something of the form ‘A’ is true if and only if A’.
 The theorist of truth conditions should insist that not every true statement about the reference of an expression be fit to be an axiom in a meaning-giving theory of truth for a language. The axiom:
  London’ refers to the city in which there was a huge fire in 1666
   is a true statement about the reference of ‘London?’. It is a consequence of a theory that substitutes this axiom for A! In our simple truth theory that ‘London is beautiful’ is true if and only if the city in which there was a huge fire in 1666 is beautiful. Since a subject can understand the name ‘London’ without knowing that last-mentioned truth conditions, this replacement axiom is not fit to be an axiom in a meaning-specifying truth theory. It is, of course, incumbent on a theorist of meaning as truth conditions to state the constraints on the acceptability of axioms in a way that does not presuppose a deductive, non-truth conditional conception of meaning.
Among the many challenges facing the theorist of truth conditions, two are particularly salient and fundamental. First, the theorist has to answer the charge of triviality or vacuity. Second, the theorist must offer an account of what it is for a person’s language to be truly descriptive by a semantic theory containing a given semantic axiom.
 We can take the charge of triviality first. In more detail, it would run thus: Since the content of a claim that the sentence ‘Paris is beautiful’ in which is true of the divisional region, which is no more than the claim that Paris is beautiful, we can trivially describe understanding a sentence, if we wish, as knowing its truth-conditions, but this gives ‘us’ no substantive account of understanding whatsoever. Something other than a grasp to truth conditions must provide the substantive account. The charge rests upon what has been called the redundancy theory of truth, the theory that, is somewhat more discriminative. Horwich calls the minimal theory of truth, or deflationary view of truth, as fathered by Fridge and Ramsey. The essential claim is that the predicate’ . . . is true’ does not have a sense, i.e., expresses no substantive or profound or explanatory concepts that ought be the topic of philosophical enquiry. The approach admits of different versions, but centres on the points (1) that ‘it is true that p’ says no more nor less than ‘p’ (hence redundancy) (2) that in less direct context, such as ‘everything he said was true’, or ‘all logical consequences of true propositions are true’, the predicate functions as a device enabling ‘us’; to generalize than as an adjective or predicate describing the thing he said, or the kinds of propositions that follow from true propositions. For example, the second may translate as ‘ (∀ p, q) (p & p  ➝ q  ➝q) ‘ where there is no use of a notion of truth.
 There are technical problems in interpreting all uses of the notion of truth in such ways, but they are not generally felt to be insurmountable. The approach needs to explain away apparently substantive uses of the notion, such a; science aims at the truth’, or ‘truth is a norm governing discourse’. Indeed, postmodernist writing frequently advocates that we must abandon such norms, along with a discredited ‘objective’ conception of truth. But perhaps, we can have the norms even when objectivity is problematic, since they can be framed without mention of truth: Science wants it to be so that whenever science holds that ‘p’. Then ‘p’. Discourse is to be regulated by the principle that it is wrong to assert ‘p’ when ‘not-p’.
 The disquotational theory of truth finds that the simplest formulation is the claim that expressions of the fern ‘S is true’ mean the same as expressions of the form ’S’. Some philosophers dislike the idea of sameness of meaning, and if this is disallowed, then the claim is that the two forms are equivalent in any sense of equivalence that matters. That is, it makes no difference whether people say ‘Dogs bark’ is true, or whether they say that ‘dogs bark’. In the former representation of what they say the sentence ‘Dogs bark’ is mentioned, but in the latter it appears to be used, so the claim that the two are equivalent needs careful formulation and defence. On the face of it someone might know that ‘Dogs bark’ is true without knowing what it means, for instance, if one were to find it in a list of acknowledged truths, although he does not understand English, and this is different from knowing that dogs bark. Disquotational theories are usually presented as versions of the redundancy theory of truth.
 The minimal theory states that the concept of truth is exhausted by the fact that it conforms to the equivalence principle, the principle that for any proposition ‘p’, it is true that ‘p’ if and only if ‘p’. Many different philosophical theories of truth will, with suitable qualifications, accept that equivalence principle. The distinguishing feature of the minimal theory is its claim that the equivalence principle exhausts the notion of truths. It is how widely accepted, that both by opponents and supporters of truth conditional theories of meaning, that it is inconsistent to accept both minimal theory of truth and a truth conditional account of meaning (Davidson, 1990, Dummett, 1959 and Horwich, 1990). If the claim that the sentence ‘Paris is beautiful’ is true is exhausted by its equivalence to the claim that Paris is beautiful, it is circular to try to explain the sentence’s meaning in terms of its truth conditions. The minimal theory of truth has been endorsed by Ramsey, Ayer, the later Wittgenstein, Quine, Strawson, Horwich and-confusingly and inconsistently if be it correct-Fridge himself. But is the minimal theory correct?
 The minimal or redundancy theory treats instances of the equivalence principle as definitional of truth for a given sentence. But in fact, it seems that each instance of the equivalence principle can itself be explained. The truths from which such an instance as:
     ‘London is beautiful’ is true if and only if London is beautiful
preserve a right to be interpreted specifically of A1 and A3 above? This would be a pseudo-explanation if the fact that ‘London’ refers to ‘London is beautiful’ has the truth-condition it does. But that is very implausible: It is, after all, possible to understand the name ‘London’ without understanding the predicate ‘is beautiful’. The idea that facts about the reference of particular words can be explanatory of facts about the truth conditions of sentences containing them in no way requires any naturalistic or any other kind of reduction of the notion of reference. Nor is the idea incompatible with the plausible point that singular reference can be attributed at all only to something that is capable of combining with other expressions to form complete sentences. That still leaves room for facts about an expression’s having the particular reference it does to be partially explanatory of the particular truth condition possessed by a given sentence containing it. The minimal; theory thus treats as definitional or stimulative something that is in fact open to explanation. What makes this explanation possible is that there is a general notion of truth that has, among the many links that hold it in place, systematic connections with the semantic values of sub-sentential expressions.
 A second problem with the minimal theory is that it seems impossible to formulate it without at some point relying implicitly on features and principles involving truths that go beyond anything countenanced by the minimal theory. If the minimal theory treats truth as a predicate of anything linguistic, be it utterances, type-in-a-language, or whatever, then the equivalence schema will not cover all cases, but only those in the theorist’s own language. Some account has to be given of truth for sentences of other languages. Speaking of the truth of language-independence propositions or thoughts will only postpone, not avoid, this issue, since at some point principles have to be stated associating these language-independent entities with sentences of particular languages. The defender of the minimalist theory is likely to say that if a sentence ‘S’ of a foreign language is best translated by our sentence ‘p’, then the foreign sentence ‘S’ is true if and only if ‘p’. Now the best translation of a sentence must preserve the concepts expressed in the sentence. Constraints involving a general notion of truth are persuasive in a plausible philosophical theory of concepts. It is, for example, a condition of adequacy on an individualized account of any concept that there exists what is called ‘Determination Theory’ for that account-that is, a specification of how the account contributes to fixing the semantic value of that concept, the notion of a concept’s semantic value is the notion of something that makes a certain contribution to the truth conditions of thoughts in which the concept occurs. but this is to presuppose, than to elucidate, a general notion of truth.
 It is also plausible that there are general constraints on the form of such Determination Theories, constraints that involve truth and which are not derivable from the minimalist’s conception. Suppose that concepts are individuated by their possession conditions. A concept is something that is capable of being a constituent of such contentual representational in a way of thinking of something-a particular object, or property, or relation, or another entity. A possession condition may in various says makes a thanker’s possession of a particular concept dependent upon his relations to his environment. Many possession conditions will mention the links between a concept and the thinker’s perceptual experience. Perceptual experience represents the world for being a certain way. It is arguable that the only satisfactory explanation of what it is for perceptual experience to represent the world in a particular way must refer to the complex relations of the experience to the subject’s environment. If this is so, then mention of such experiences in a possession condition will make possession of that condition will make possession of that concept dependent in part upon the environment relations of the thinker. Burge (1979) has also argued from intuitions about particular examples that, even though the thinker’s non-environmental properties and relations remain constant, the conceptual content of his mental state can vary if the thinker’s social environment is varied. A possession condition which property individuates such a concept must take into account the thinker’s social relations, in particular his linguistic relations.
 One such plausible general constraint is then the requirement that when a thinker forms beliefs involving a concept in accordance with its possession condition, a semantic value is assigned to the concept in such a way that the belief is true. Some general principles involving truth can indeed, as Horwich has emphasized, be derived from the equivalence schema using minimal logical apparatus. Consider, for instance, the principle that ‘Paris is beautiful and London is beautiful’ is true if and only if ‘Paris is beautiful’ is true if and only if ‘Paris is beautiful’ is true and ‘London is beautiful’ is true. This follows logically from the three instances of the equivalence principle: ‘Paris is beautiful and London is beautiful’ is rue if and only if Paris is beautiful, and ‘London is beautiful’ is true if and only if London is beautiful. But no logical manipulations of the equivalence schemas will allow the deprivation of that general constraint governing possession conditions, truth and the assignment of semantic values. That constraint can have courses be regarded as a further elaboration of the idea that truth is one of the aims of judgement.
 We now turn to the other question, ‘What is it for a person’s language to be correctly describable by a semantic theory containing a particular axiom, such as the axiom A6 above for conjunction?’ This question may be addressed at two depths of generality. At the shallower level, the question may take for granted the person’s possession of the concept of conjunction, and be concerned with what has to be true for the axiom correctly to describe his language. At a deeper level, an answer should not duck the issue of what it is to possess the concept. The answers to both questions are of great interest: We will take the lesser level of generality first.
 When a person means conjunction by ‘sand’, he is not necessarily capable of formulating the axiom A6 explicitly. Even if he can formulate it, his ability to formulate it is not the causal basis of his capacity to hear sentences containing the word ‘and’ as meaning something involving conjunction. Nor is it the causal basis of his capacity to mean something involving conjunction by sentences he utters containing the word ‘and’. Is it then right to regard a truth theory as part of an unconscious psychological computation, and to regard understanding a sentence as involving a particular way of depriving a theorem from a truth theory at some level of conscious proceedings? One problem with this is that it is quite implausible that everyone who speaks the same language has to use the same algorithms for computing the meaning of a sentence. In the past thirteen years, thanks particularly to the work of Davies and Evans, a conception has evolved according to which an axiom like A6 is true of a person’s language only if there is a common component in the explanation of his understanding of each sentence containing the word ‘and’, a common component that explains why each such sentence is understood as meaning something involving conjunction (Davies, 1987). This conception can also be elaborated in computational terms: Suggesting that for an axiom like A6 to be true of a person’s language is for the unconscious mechanisms which produce understanding to draw on the information that a sentence of the form ‘A and B’ are true if and only if ‘A’ is true and ‘B’ is true (Peacocke, 1986). Many different algorithms may equally draw n this information. The psychological reality of a semantic theory thus involves, in Marr’s (1982) famous classification, something intermediate between his level one, the function computed, and his level two, the algorithm by which it is computed. This conception of the psychological reality of a semantic theory can also be applied to syntactic and phonol logical theories. Theories in semantics, syntax and phonology are not themselves required to specify the particular algorithms that the language user employs. The identification of the particular computational methods employed is a task for psychology. But semantics, syntactic and phonology theories are answerable to psychological data, and are potentially refutable by them-for these linguistic theories do make commitments to the information drawn upon by mechanisms in the language user.
 This answer to the question of what it is for an axiom to be true of a person’s language clearly takes for granted the person’s possession of the concept expressed by the word treated by the axiom. In the example of the axiom A6, the information drawn upon is that sentences of the form ‘A and B’ are true if and only if ‘A’ is true and ‘B’ is true. This informational content employs, as it has to if it is to be adequate, the concept of conjunction used in stating the meaning of sentences containing ‘and’. So the computational answer we have returned needs further elaboration if we are to address the deeper question, which does not want to take for granted possession of the concepts expressed in the language. It is at this point that the theory of linguistic understanding has to draws upon a theory of concepts. It is plausible that the concepts of conjunction are individuated by the following condition for a thinker to possess it.
 Finally, this response to the deeper question allows ‘us’ to answer two challenges to the conception of meaning as truth-conditions. First, there was the question left hanging earlier, of how the theorist of truth-conditions is to say what makes one axiom of a semantic theory is correctly in  that of another, when the two axioms assign the same semantic values, but do so by means of different concepts. Since the different concepts will have different possession conditions, the dovetailing accounts, at the deeper level of what it is for each axiom to be correct for a person’s language will be different accounts. Second, there is a challenge repeatedly made by the minimalist theorists of truth, to the effect that the theorist of meaning as truth-conditions should give some non-circular account of what it is to understand a sentence, or to be capable of understanding all sentences containing a given constituent. For each expression in a sentence, the corresponding dovetailing account, together with the possession condition, supplies a non-circular account of what it is to understand any sentence containing that expression. The combined accounts for each of he expressions that comprise a given sentence together constitute a non-circular account of what it is to understand the compete sentences. Taken together, they allow the theorists of meaning as truth-conditions fully to meet the challenge.
 A curious view common to that which is expressed by an utterance or sentence: The proposition or claim made about the world. By extension, the content of a predicate or other sub-sentential component is what it contributes to the content of sentences that contain it. The nature of content is the central concern of the philosophy of language, in that mental states have contents: A belief may have the content that the prime minister will resign. A concept is something that is capable of bringing a constituent of such contents. More specifically, a concept is a way of thinking of something-a particular object, or property or relation, or another entity. Such a distinction was held in Frége’s philosophy of language, explored in ‘On Concept and Object’ (1892). Fridge regarded predicates as incomplete expressions, in the same way as a mathematical expression for a function, such as sines . . . a log . . . , is incomplete. Predicates refer to concepts, which themselves are ‘unsaturated’, and cannot be referred to by subject expressions (we thus get the paradox that the concept of a horse is not a concept). Although Fridge recognized the metaphorical nature of the notion of a concept being unsaturated, he was rightly convinced that some such notion is needed to explain the unity of a sentence, and to prevent sentences from being thought of as mere lists of names.
 Several different concepts may each be ways of thinking of the same object. A person may think of himself in the first-person way, or think of himself as the spouse of Mary Smith, or as the person located in a certain room now. More generally, a concept ‘c’ is distinct from a concept ‘d’ if it is possible for a person rationally to believe ‘d is such-and-such’. As words can be combined to form structured sentences, concepts have also been conceived as combinable into structured complex contents. When these complex contents are expressed in English by ‘that  . . . ’clauses, as in our opening examples, they will be capable of being true or false, depending on the way the world is.
 The general system of concepts with which we organize our thoughts and perceptions are to encourage a conceptual scheme of which the outstanding elements of our every day conceptual formalities include spatial and temporal relations between events and enduring objects, causal relations, other persons, meaning-bearing utterances of others, . . . and so on. To see the world as containing such things is to share this much of our conceptual scheme. A controversial argument of Davidson’s urges that we would be unable to interpret speech from a different conceptual scheme as even meaningful, Davidson daringly goes on to argue that since translation proceeds according ti a principle of clarity, and since it must be possible of an omniscient translator to make sense of, ‘us’ we can be assured that most of the beliefs formed within the commonsense conceptual framework are true.
 Concepts are to be distinguished from a stereotype and from conceptions. The stereotypical spy may be a middle-level official down on his luck and in need of money. None the less, we can come to learn that Anthony Blunt, art historian and Surveyor of the Queen’s Pictures, are a spy; we can come to believe that something falls under a concept while positively disbelieving that the same thing falls under the stereotype associated wit the concept. Similarly, a person’s conception of a just arrangement for resolving disputes may involve something like contemporary Western legal systems. But whether or not it would be correct, it is quite intelligible for someone to rejects this conception by arguing that it dies not adequately provide for the elements of fairness and respect that are required by the concepts of justice.
 Basically, a concept is that which is understood by a term, particularly a predicate. To posses a concept is to be able to deploy a term expressing it in making judgements, in which the ability connection is such things as recognizing when the term applies, and being able to understand the consequences of its application. The term ‘idea’ was formally used in the came way, but is avoided because of its associations with subjective matters inferred upon mental imagery in which may be irrelevant ti the possession of a concept. In the semantics of Fridge, a concept is the reference of a predicate, and cannot be referred to by a subjective term, although its recognition of as a  concept, in that some such notion is needed to the explanatory justification of which that sentence of unity finds of itself from being thought of as namely categorized lists of itemized priorities.
 A theory of a particular concept must be distinguished from a theory of the object or objects it selectively picks the outlying of the theory of the concept under which is partially contingent of the theory of thought and/or epistemology. A theory of the object or objects is part of metaphysics and ontology. Some figures in the history of philosophy-and are open to the accusation of not having fully respected the distinction between the kinds of theory. Descartes appears to have moved from facts about the indubitability of the thought ‘I think’, containing the fist-person was of thinking, to conclusions about the nonmaterial nature of the object he himself was. But though the goals of a theory of concepts and a theory of objects are distinct, each theory is required to have an adequate account of its relation to the other theory. A theory if concept is unacceptable if it gives no account of how the concept is capable of picking out the object it evidently does pick out. A theory of objects is unacceptable if it makes it impossible to understand how we could have concepts of those objects.
 A fundamental question for philosophy is: What individuates a given concept-that is, what makes it the one it is, rather than any other concept? One answer, which has been developed in great detail, is that it is impossible to give a non-trivial answer to this question (Schiffer, 1987). An alternative approach, addressees the question by starting from the idea that a concept id individuated by the condition that must be satisfied if a thinker is to posses that concept and to be capable of having beliefs and other attitudes whose content contains it as a constituent. So, to take a simple case, one could propose that the logical concept ‘and’ is individuated by this condition, it be the unique concept ‘C’ to posses that a thinker has to find these forms of inference compelling, without basing them on any further inference or information: From any two premisses ‘A’ and ‘B’, ACB can be inferred, and from any premiss ACB, each of ‘A’ and ‘B’ can be inferred. Again, a relatively observational concept such as ‘round’ can be individuated in part by stating that the thinker finds specified contents containing it compelling when he has certain kinds of perception, and in part by relating those judgements containing the concept and which are not based on perception to those judgements that are. A statement that individuates a concept by saying what is required for a thinker to posses it can be described as giving the possession condition for the concept.
 A possession condition for a particular concept may actually make use of that concept. The possession condition for ‘and’ does so. We can also expect to use relatively observational concepts in specifying the kind of experience that have to be mentioned in the possession conditions for relatively observational concepts. What we must avoid is mention of the concept in question as such within the content of the attitudes attributed to the thinker in the possession condition. Otherwise we would be presupposing possession of the concept in an account that was meant to elucidate its possession. In talking of what the thinker finds compelling, the possession conditions can also respect an insight of the later Wittgenstein: That to find her finds it natural to go on in new cases in applying the concept.
 Sometimes a family of concepts has this property: It is not possible to master any one of the members of the family without mastering the others. Two of the families that plausibly have this status are these: The family consisting of some simple concepts 0, 1, 2, . . . of the natural numbers and the corresponding concepts of numerical quantifiers there are 0 so-and-so, there is 1 so-and-so, . . . and the family consisting of the concepts; belief’ and ‘desire’. Such families have come to be known as ‘local holism’. A local holism does not prevent the individuation of a concept by its possession condition. Rather, it demands that all the concepts in the family be individuated simultaneously. So one would say something of this form: Belief and desire form the unique pair of concepts C1 and C2 such that for as thinker to posses them are to meet such-and-such condition involving the thinker, C1 and C2. For these and other possession conditions to individuate properly, it is necessary that there be some ranking of the concepts treated. The possession conditions for concepts higher in the ranking must presuppose only possession of concepts at the same or lower levels in the ranking.
 A possession conditions may in various way’s make a thinker’s possession of a particular concept dependent upon his relations to his environment. Many possession conditions will mention the links between a concept and the thinker’s perceptual experience. Perceptual experience represents the world as a certain way. It is arguable that the only satisfactory explanation of what it is for perceptual experience to represent the world in a particular way must refer to the complex relations of the experience to the subject’s environment. If this is so, then mention of such experiences in a possession condition will make possession of that concept dependent in part upon the environmental relations of the thinker. Burge (1979) has also argued from intuitions about particular examples that, even though the thinker’s non-environmental properties and relations remain constant, the conceptual content of his mental state can vary if the thinker’s social environment is varied. A possession condition that properly individuates such a concept must take into account the thinker’s social relations, in particular his linguistic relations.
 Concepts have a normative dimension, a fact strongly emphasized by Kripke. For any judgement whose content involves a given concept, there is a correctness condition for that judgement, a condition that is dependent in part upon the identity of the concept. The normative character of concepts also extends into making the territory of a thinker’s reasons for making judgements. A thinker’s visual perception can give him good reason for judging ‘That man is bald’: It does not by itself give him good reason for judging ‘Rostropovich ids bald’, even if the man he sees is Rostropovich. All these normative connections must be explained by a theory of concepts one approach to these matters is to look to the possession condition for the concept, and consider how the referent of a concept is fixed from it, together with the world. One proposal is that the referent of the concept is that object (or property, or function, . . .) which makes the practices of judgement and inference mentioned in the possession condition always lead to true judgements and truth-preserving inferences. This proposal would explain why certain reasons are necessity good reasons for judging given contents. Provided the possession condition permits ‘us’ to say what it is about a thinker’s previous judgements that masker it, the case that he is employing one concept rather than another, this proposal would also have another virtue. It would allow ‘us’ to say how the correctness condition is determined for a judgement in which the concept is applied to newly encountered objects. The judgement is correct if the new object has the property that in fact makes the judgmental practices mentioned in the possession condition yield true judgements, or truth-preserving inferences.
 These manifesting dissimilations have occasioned the affiliated differences accorded within the distinction as associated with Leibniz, who declares that there are only two kinds of truths-truths of reason and truths of fact. The forms are all either explicit identities, i.e., of the form ‘A is A’, ‘AB is B’, etc., or they are reducible to this form by successively substituting equivalent terms. Leibniz dubs them ‘truths of reason’ because the explicit identities are self-evident deducible truths, whereas the rest can be converted to such by purely rational operations. Because their denial involves a demonstrable contradiction, Leibniz also says that truths of reason ‘rest on the principle of contradiction, or identity’ and that they are necessary [propositions, which are true of all possible words. Some examples are ‘All equilateral rectangles are rectangles’ and ‘All bachelors are unmarried’: The first is already of the form AB is B’ and the latter can be reduced to this form by substituting ‘unmarried man’ fort ‘bachelor’. Other examples, or so Leibniz believes, are ‘God exists’ and the truths of logic, arithmetic and geometry.
 Truths of fact, on the other hand, cannot be reduced to an identity and our only way of knowing them is empirically by reference to the facts of the empirical world. Likewise, since their denial does not involve a contradiction, their truth is merely contingent: They could have been otherwise and hold of the actual world, but not of every possible one. Some examples are ‘Caesar crossed the Rubicon’ and ‘Leibniz was born in Leipzig’, as well as propositions expressing correct scientific generalizations. In Leibniz’s view, truths of fact rest on the principle of sufficient reason, which states that nothing can be so unless there is a reason that it is so. This reason is that the actual world (by which he means the total collection of things past, present and future) is better than any other possible worlds and was therefore created by ‘God’.
 In defending the principle of sufficient reason, Leibniz runs into serious problems. He believes that in every true proposition, the concept of the predicate is contained in that of the subject. (This holds even for propositions like ‘Caesar crossed the Rubicon’: Leibniz thinks anyone who dids not cross the Rubicon, would not have been Caesar). And this containment relationship! Which is eternal and unalterable even by God ~?! Guarantees that every truth has a sufficient reason. If truths consists in concept containment, however, then it seems that all truths are analytic and hence necessary, and if they are all necessary, surely they are all truths of reason. Leibnitz responds that not every truth can be reduced to an identity in a finite number of steps, in some instances revealing the connection between subject and predicate concepts would requite an infinite analysis. But while this may entail that we cannot prove such propositions as deductively manifested, it does not appear to show that the proposition could have been false. Intuitively, it seems a better ground for supposing that it is necessary truth of a special sort. A related question arises from the idea that truths of fact depend on God’s decision to create.
the best of all possible worlds: If it is part of the concept of this world that it is best, now could its existence be other than necessary? Leibniz answers that its existence is only hypothetically necessary, i.e., it follows from God’s decision to create this world, but God had the power to decide otherwise. Yet God is necessarily good and non-deceiving, so how could he have decided to do anything else? Leibniz says much more about these masters, but it is not clear whether he offers any satisfactory solutions.
 Necessary truths are ones that must be true, or whose opposite is impossible. Contingent truths are those that are not necessary and whose opposite is therefore possible. 1-3 below is necessary, 4-6, contingent.
1. It is not the case that it is raining and not raining
2. 2 + 2= 4
3. All bachelors are unmarried.
4. It seldom rains in the Sahara.
5. There are more than four states in the USA.
6. Some bachelors drive Maserati.
Plantinga (1974, p. 2) characterizes the sense of necessity illustrated in 1-3 as ‘broadly logical’. For it includes not only truths of logic, but those of mathematics, set theory, and other quasi-logical ones. Yet it is not so broads as to include matters of causal or natural necessity, such as: Nothing travels faster than the speed of light.
One would like an account of the basis of our distinction and a criterion by which to apply it. Some suppose that necessary truths are those we know as deductively possible. But we lack the criterion for deductive truths, and there are necessary truths we do not know at all, e.g., undiscovered mathematical ones. It would not help to say that necessary truths are one, and it is possible, in the broadly logical sense, to know of a deductive circularity. Finally, Kripke (1972, p.253 v) and Plantinga (1974, p. 8) argues that some contingent truths are knowable by deductive reasoning. Similar problems face the suggestion that necessary truths are the ones we know with the fairest of certainties: We lack a criterion for certainty, there are necessary truths we do not know, and (barring dubious arguments for scepticism) it is reasonable to suppose that we know some contingent truths with certainty.
 Leibniz defined a necessary truth as one whose opposite implies a contradiction. Every such proposition, he held, is either an explicit identity, i.e., of the form ‘A is A’, ‘AB is B’, etc.) or is reducible to an identity by successively substituting equivalent terms. (thus, 3 above might be so reduced by substituting ‘unmarried man’; for ‘bachelor’.) This has several advantages over the ideas of the previous paragraph. First, it explicated the notion of necessity and possibility and seems to provide a criterion we can apply. Second, because explicit identities are self-evident a deductive propositions, the theory implies that all necessary truths are knowable deductively, but it does not entail that wee actually know all of them, nor does it define ‘knowable’ in a circular way. Third, it implies that necessary truths are knowable with certainty, but does not preclude our having certain knowledge of contingent truths by means other than a reduction.
 Nevertheless, this view is also problematic, and Leibniz’s examples of reductions are too sparse to prove a claim about all necessary truths. Some of his reductions, moreover, are deficient: Fridge has pointed out, for example, that his proof of ‘2 + 2 = 4' presupposes the principle of association and so does not depend on the principle of identity. More generally, it has been shown that arithmetic cannot be reduced to logic, but requires the resources of set theory as well. Finally, there are other necessary propositions, e.g., ‘Nothing can be red and green all over’, which do not seem to be reducible to identities and which Leibniz does not show how to reduce.
 Leibniz and others have thought of truths as a property of propositions, where the latter are conceived as things that may be expressed by, but are distinct from, linguistic items like statements. On another approach, truth is a property of linguistic entities, and the basis of necessary truth in convention. Thus A.J. Ayer, for example, . Argued that the only necessary truths are analytic statements and that the latter rest entirely on our commitment to use words in certain ways.
 The slogan ‘the meaning of a statement is its method of verification’ expresses the empirical verification’s theory of meaning. It is more than the general criterion of meaningfulness if and only if it is empirically verifiable. If says in addition what the meaning of a sentence is: It is all those observations that would confirm or disconfirmed the sentence. Sentences that would be verified or falsified by all the same observations are empirically equivalent or have the same meaning. A sentence is said to be cognitively meaningful if and only if it can be verified or falsified in experience. This is not meant to require that the sentence be conclusively verified or falsified, since universal scientific laws or hypotheses (which are supposed to pass the test) are not logically deducible from any amount of actually observed evidence.
 When one predicate’s necessary truth of a preposition one speaks of modality dedicto. For one ascribes the modal property, necessary truth, to a dictum, namely, whatever proposition is taken as necessary. A venerable tradition, however, distinguishes this from necessary de re, wherein one predicates necessary or essential possession of some property to an on object. For example, the statement ‘4 is necessarily greater than 2' might be used to predicate of the object, 4, the property, being necessarily greater than 2. That objects have some of their properties necessarily, or essentially, and others only contingently, or accidentally, are a main part of the doctrine called; essentialism’. Thus, an essentials might say that Socrates had the property of being bald accidentally, but that of being self-identical, or perhaps of being human, essentially. Although essentialism has been vigorously attacked in recent years, most particularly by Quine, it also has able contemporary proponents, such as Plantinga.
 Modal necessity as seen by many philosophers whom have traditionally held that every proposition has a modal status as well as a truth value. Every proposition is either necessary or contingent as well as either true or false. The issue of knowledge of the modal status of propositions has received much attention because of its intimate relationship to the issue of deductive reasoning. For example, no propositions of the theoretic content that all knowledge of necessary propositions is deductively knowledgeable. Others reject this claim by citing Kripke’s (1980) alleged cases of necessary theoretical propositions. Such contentions are often inconclusive, for they fail to take into account the following tripartite distinction: ‘S’ knows the general modal status of ‘p’ just in case ‘S’ knows that ‘p’ is a necessary proposition or ‘S’ knows the truth that ‘p’ is a contingent proposition. ‘S’ knows the truth value of ‘p’ just in case ‘S’ knows that ‘p’ is true or ‘S’ knows that ‘p’ is false. ‘S’ knows the specific modal status of ‘p’ just in case ‘S’ knows that ‘p’ is necessarily true or ‘S’ knows that ‘p’ is necessarily false or ‘S’ knows that ‘p’ is contingently true or ‘S’ knows that ‘p’ is contingently false. It does not follow from the fact that knowledge of the general modal status of a proposition is a deductively reasoned distinctive modal status is also given to theoretical principles. Nor des it follow from the fact that knowledge of a specific modal status of a proposition is theoretically given as to the knowledge of its general modal status that also is deductive.
 The certainties involving reason and a truth of fact are much in distinction by associative measures given through Leibniz, who declares that there are only two kinds of truths-truths of reason and truths of fact. The former are all either explicit identities, i.e., of the form ‘A is A’, ‘AB is B’, etc., or they are reducible to this form by successively substituting equivalent terms. Leibniz dubs them ‘truths of reason’ because the explicit identities are self-evident theoretical truth, whereas the rest can be converted to such by purely rational operations. Because their denial involves a demonstrable contradiction, Leibniz also says that truths of reason ‘rest on the principle of contraction, or identity’ and that they are necessary propositions, which are true of all possible worlds. Some examples are that All bachelors are unmarried’: The first is already of the form ‘AB is B’ and the latter can be reduced to this form by substituting ‘unmarried man’ for ‘bachelor’. Other examples, or so Leibniz believes, are ‘God exists’ and the truth of logic, arithmetic and geometry.
 Truths of fact, on the other hand, cannot be reduced to an identity and our only way of knowing hem os a theoretical manifestations, or by reference to the fact of the empirical world. Likewise, since their denial does not involve as contradiction, their truth is merely contingent: They could have been otherwise and hold of the actual world, but not of every possible one. Some examples are ‘Caesar crossed the Rubicon’ and ‘Leibniz was born in Leipzig’, as well as propositions expressing correct scientific generalizations. In Leibniz’s view, truths of fact rest on the principle of sufficient reason, which states that nothing can be so unless thee is a reason that it is so. This reason is that the actual world (by which he means the total collection of things past, present and future) is better than any other possible world and was therefore created by God.
 In defending the principle of sufficient reason, Leibniz runs into serious problems. He believes that in every true proposition, the concept of the predicate is contained in that of the subject. (This hols even for propositions like ‘Caesar crossed the Rubicon’: Leibniz thinks anyone who did not cross the Rubicon would not have been Caesar) And this containment relationship-that is eternal and unalterable even by God-guarantees that every truth has a sufficient reason. If truth consists in concept containment, however, then it seems that all truths are analytic and hence necessary, and if they are all necessary, surely they are all truths of reason. Leibniz responds that not evert truth can be reduced to an identity in a finite number of steps: In some instances revealing the connection between subject and predicate concepts would require an infinite analysis. But while this may entail that we cannot prove such propositions as deductively probable, it does not appear to show that the proposition could have been false. Intuitively, it seems a better ground for supposing that it is a necessary truth of a special sort. A related question arises from the idea that truths of fact depend on God’s decision to create the best world, if it is part of the concept of this world that it is best, how could its existence be other than necessary? Leibniz answers that its existence is only hypothetically necessary, i.e., it follows from God’s decision to create this world, but God is necessarily good, so how could he have decided to do anything else? Leibniz says much more about the matters, but it is not clear whether he offers any satisfactory solutions.
 The modality of a proposition is the way in which it is true or false. The most important division is between propositions true of necessity, and those true asa things are: Necessary as opposed to contingent propositions. Other qualifiers sometimes called ‘modal’ include the tense indicators ‘It will be the case that p’ or It was the case that p’, and there are affinities between the ‘deontic indicators’, as it ought to be the case that p’ or ‘it is permissible that p’, and the logical modalities as a logic that study the notions of necessity and possibility. Modal logic was of a great importance historically, particularly in the light of various doctrines concerning the necessary properties of the deity, but was not a central topic of modern logic in its golden period at the beginning of the 20th century. It was, however, revived by C. I. Lewis, by adding to a propositional or predicate calculus two operators, □ and ◊ (sometimes written N and M), meaning necessarily and possibly, respectively. These like p ➞ ◊ p and □ p ➞ p will be wanted. Controversial theses include □ p ➞ □□ p (if a proposition is necessary, it is necessarily necessary, characteristic of the system known as S4) and ◊ p ➞ □ ◊ p (if a proposition is possible, it is necessarily possible, characteristic of the system known as S5). The classical ‘modal theory’ for modal logic, due to Kripke and the Swedish logician Stig Kanger, involves valuing propositions not as true or false ‘simplicitiers’, but as true or false art possible worlds, with necessity then corresponding to truth in all worlds, and possibly to truths in some world.
 The doctrine advocated by David Lewis, which different ‘possible worlds’ are to be thought of as existing exactly as this one does. Thinking in terms of possibilities is thinking of real worlds where things are different, this view has been charged with misrepresenting it as some insurmountably unseeing to why it is good to save the child from drowning, since there is still a possible world in which she (or her counterpart) drowned, and from the standpoint of the universe it should make no difference that world is actual. Critics asio charge either that the notion fails to fit with a coherent theory of how we know about possible worlds, or with a coherent theory about possible worlds, or with a coherent theory of why we are interested in them, but Lewis denies that any other way of interpreting modal statements is tenable.
 Thus and so, the ‘standard analysis’ of propositional knowledge, suggested by Plato and Kant among others, implies that if one has a justified true belief that ‘p’, then one knows that ‘p’. The belief condition ‘p’ believes that ‘p’, the truth condition requires that any known proposition be true. And the justification condition requires that any known proposition be adequately justified, warranted or evidentially supported. Plato appears to be considering the tripartite definition in the ‘Theaetetus’ (201c-202d), and to be endorsing its jointly sufficient conditions for knowledge in the ‘Meno’ (97e-98a). This definition has come to be called ‘the standard analysis’ of knowledge, and has received a serious challenge from Edmund Gettier’s counterexamples in 1963. Gettier published two counterexamples to this implication of the standard analysis. In essence, they are:
   (1) Smith and Jones have applied for the same job. Smith is justified in believing that (a) Jones will get the job, and that (b) Jones has ten coins in his pocket. On the basis of (a) and (b) Smith infers, and thus is justified in believing, that ©) the person who will get the job has ten coins in his pocket. At it turns out, Smith himself will get the job, and he also happens to have ten coins in his pocket. So, although Smith is justified in believing the true proposition ©), Smith does not know ©).
   (2) Smith is justified in believing the false proposition that (a) Smith owns a Ford. On the basis of (a) Smith infers, and thus is justified in believing, that (b) either Jones owns a Ford or Brown is in Barcelona. As it turns out, Brown or in Barcelona, and so (b) is true. So although Smith is justified in believing the true proposition (b). Smith does not know (b).
 Gettier’s counterexamples are thus cases where one has justified true belief that ‘p’, but lacks knowledge that ‘p’. The Gettier problem is the problem of finding a modification of, or an alterative to, the standard justified-true-belief analysis of knowledge that avoids counterexamples like Gettier’s. Some philosophers have suggested that Gettier style counterexamples are defective owing to their reliance on the false principle that false propositions can justify one’s belief in other propositions. But there are examples much like Gettier’s that do not depend on this allegedly false principle. Here is one example inspired by Keith and Richard Feldman:
   (3) Suppose Smith knows the following proposition, ‘m’: Jones, whom Smith has always found to be reliable and whom Smith, has no reason to distrust now, has told Smith, his office-mate, that ‘p’: He, Jones owns a Ford. Suppose also that Jones has told Smith that ‘p’ only because of a state of hypnosis Jones is in, and that ‘p’ is true only because, unknown to himself, Jones has won a Ford in a lottery since entering the state of hypnosis. And suppose further that Smith deduces from ‘m’ its existential generalization, ‘q’: There is someone, whom Smith has always found to be reliable and whom Smith has no reason to distrust now, who has told Smith, his office-mate, that he owns a Ford. Smith, then, knows that ‘q’, since he has correctly deduced ‘q’ from ‘m’, which he also knows. But suppose also that on the basis of his knowledge that ‘q’. Smith believes that ‘r’: Someone in the office owns a Ford. Under these conditions, Smith has justified true belief that ‘r’, knows his evidence for ‘r’, but does not know that ‘r’.
 Gettier-style examples of this sort have proven especially difficult for attempts to analyse the concept of propositional knowledge. The history of attempted solutions to the Gettier problem is complex and open-ended.  It has not produced consensus on any solution. Many philosophers hold, in light of Gettier-style examples, that propositional knowledge requires a fourth condition, beyond the justification, truth and belief conditions. Although no particular fourth condition enjoys widespread endorsement, there are some prominent general proposals in circulation. One sort of proposed modification, the so-called ‘defeasibility analysis’, requires that the justification appropriate to knowledge be ‘undefeated’ in the general sense that some appropriate subjunctive conditional concerning genuine defeaters of justification be true of that justification. One straightforward defeasibility fourth condition, for instance, requires of Smith’s knowing that ‘p’ that there be no true proposition ‘q’, such that if ‘q’ became justified for Smith, ‘p’ would no longer be justified for Smith (Pappas and Swain, 1978). A different prominent modification requires that the actual justification for a true belief qualifying as knowledge not depend I a specified way on any falsehood (Armstrong, 1973). The details proposed to elaborate such approaches have met with considerable controversy.
 The fourth condition of evidential truth-sustenance may be a speculative solution to the Gettier problem. More specifically, for a person, ‘S’, to have knowledge that ‘p’ on justifying evidence ‘e’, ‘e’ must be truth-sustained in this sense for every true proposition ‘t’ that, when conjoined with ‘e’, undermines S’s justification for ‘p’ on ‘e’, there is a true proposition, ‘t’, that, when conjoined with ‘e’ & ‘t’, restores the justification of ‘p’ for ‘S’ in a way that ‘S’ is actually justified in believing that ‘p’. The gist of this resolving evolution, put roughly, is that propositional knowledge requires justified true belief that is sustained by the collective totality of truths. Herein, is to argue in Knowledge and Evidence, that Gettier-style examples as (1)-(3), but various others as well.
 Three features that proposed this solution merit emphasis. First, it avoids a subjunctive conditional in its fourth condition, and so escapes some difficult problems facing the use of such a conditional in an analysis of knowledge. Second, it allows for non-deductive justifying evidence as a component of propositional knowledge. An adequacy condition on an analysis of knowledge is that it does not restrict justifying evidence to relations of deductive support. Third, its proposed solution is sufficiently flexible to handle cases describable as follows:
   (4) Smith has a justified true belief that ‘p’, but there is a true proposition, ‘t’, which undermines Smith’s justification for ‘p’ when conjoined with it, and which is such that it is either physically or humanly impossible for Smith to be justified in believing that ‘t’.
 Examples represented by (4) suggest that we should countenance varying strengths in notions of propositional knowledge. These strengths are determined by accessibility qualifications on the set of relevant knowledge-precluding underminers. A very demanding concept of knowledge assumes that it need only be logically possible for a Knower to believe a knowledge-precluding underminer. Less demanding concepts assume that it must be physically or humanly possible for a Knower to believe knowledge-precluding underminers. But even such less demanding concepts of knowledge need to rely on a notion of truth-sustained evidence if they are to survive a threatening range of Gettier-style examples. Given to some resolution that it needs be that the forth condition for a notion of knowledge is not a function simply of the evidence a Knower actually possesses.
 The higher controversial aftermath of Gettier’s original counterexamples has left some philosophers doubted of the real philosophical significance of the Gettier problem. Such doubt, however, seems misplaced. One fundamental branch of epistemology seeks understanding of the nature of propositional knowledge. And our understanding exactly what prepositional knowledge is essentially involves our having a Gettier-resistant analysis of such knowledge. If our analysis is not Gettier-resistant, we will lack an exact understanding of what propositional knowledge is. It is epistemologically important, therefore, to have a defensible solution to the Gettier problem, however, demanding such a solution is.
 Propositional knowledge (PK) is the type of knowing whose instance are labelled by means of a phrase expressing some proposition, e.g., in English a phrase of the form ‘that h’, where some complete declarative sentence is instantial for ‘h’.
 Theories of ‘PK’ differ over whether the proposition that ‘h’ is involved in a more intimate fashion, such as serving as a way of picking out a proposition attitude required for knowing, e.g., believing that ‘h’, accepting that ‘h’ or being sure that ‘h’. For instance, the tripartite analysis or standard analysis, treats ‘PK’ as consisting in having a justified, true belief that ‘h’, the belief condition requires that anyone who knows that ‘h’ believes that ‘h’, the truth condition requires that any known proposition be true, in contrast, some regarded theories do so consider and treat ‘PK’ as the possession of specific abilities, capabilities, or powers, and that view the proposition that ‘h’ as needed to be expressed only in order to label a specific instance of ‘PK’.
 Although most theories of Propositional knowledge (PK) purport to analyse it, philosophers disagree about the goal of a philosophical analysis. Theories of ‘PK’ may differ over whether they aim to cover all species of ‘PK’ and, if they do not have this goal, over whether they aim to reveal any unifying link between the species that they investigate, e.g., empirical knowledge, and other species of knowing.
 Very many accounts of ‘PK’ have been inspired by the quest to add a fourth condition to the tripartite analysis so as to avoid Gettier-type counterexamples to it, whereby a fourth condition of evidential truth-sustenance for every true proposition when conjoined with a regaining justification, which may require the justified true belief that is sustained by the collective totality of truths that an adequacy condition of propositional knowledge not restrict justified evidences in relation of deductive support, such that we should countenance varying strengths in notions of propositional knowledge. Restoratively, these strengths are determined by accessibility qualifications on the set of relevant knowledge-precluding underminers. A very demanding concept of knowledge assumes that it need only be logically possible for a Knower to believe a knowledge-precluding undeterminers, and less demanding concepts that it must physically or humanly possible for a Knower to believe knowledge-precluding undeterminers. But even such demanding concepts of knowledge need to rely on a notion of truth-sustaining evidence if they are to survive a threatening range of Gettier-style examples. As the needed fourth condition for a notion of knowledge is not a function simply of the evidence, a Knower actually possesses. One fundamental source of epistemology seeks understanding of the nature of propositional knowledge, and our understanding exactly what propositional knowledge is essentially involves our having a Gettier-resistant analysis of such knowledge. If our analysis is not Gettier-resistant, we will lack an exact understanding of what propositional knowledge is. It is epistemologically important, therefore, to have a defensible solution to the Gettier problem, however, demanding such a solution is. And by the resulting need to deal with other counterexamples provoked by these new analyses.
 Keith Lehrer (1965) originated a Gettier-type example that has been a fertile source of important variants. It is the case of Mr Notgot, who is in one’s office and has provided some evidence, ‘e’, in response to all of which one forms a justified belief that Mr. Notgot is in the office and owns a Ford, thanks to which one arrives at the justified belief that ‘h': ‘Someone in the office owns a Ford’. In the example, ‘e’ consists of such things as Mr. Notgot’s presently showing one a certificate of Ford ownership while claiming to own a Ford and having been reliable in the past. Yet, Mr Notgot has just been shamming, and the only reason that it is true that ‘h1' is because, unbeknown to oneself, a different person in the office owns a Ford.
 Variants on this example continue to challenge efforts to analyse species of ‘PK’. For instance, Alan Goldman (1988) has proposed that when one has empirical knowledge that ‘h’, when the state of affairs (call it h*) expressed by the proposition that ‘h’ figures prominently in an explanation of the occurrence of one’s believing that ‘h’, where explanation is taken to involve one of a variety of probability relations concerning ‘h*’, and the belief state. But this account runs foul of a variant on the Notgot case akin to one that Lehrer (1979) has described. In Lehrer’s variant, Mr Notgot has manifested a compulsion to trick people into justified believing truths yet falling short of knowledge by means of concocting Gettierized evidence for those truths. It we make the trickster’s neuroses highly specific ti the type of information contained in the proposition that ‘h’, we obtain a variant satisfying Goldman’s requirement That the occurrences of ‘h*’ significantly raises the probability of one’s believing that ‘h’. (Lehrer himself (1990, pp. 103-4) has criticized Goldman by questioning whether, when one has ordinary perceptual knowledge that abn object is present, the presence of the object is what explains one’s believing it to be present.)
 In grappling with Gettier-type examples, some analyses proscribe specific relations between falsehoods and the evidence or grounds that justify one’s believing. A simple restriction of this type requires that one’s reasoning to the belief that ‘h’ does not crucially depend upon any false lemma     (such as the false proposition that Mr Notgot is in the office and owns a Ford). However, Gettier-type examples have been constructed where one does not reason through and false belief, e.g., a variant of the Notgot case where one arrives at belief that ‘h’, by basing it upon a true existential generalization of one’s evidence: ‘There is someone in the office who has provided evidence e’, in response to similar cases, Sosa (1991) has proposed that for ‘PK’ the ‘basis’ for the justification of one’s belief that ‘h’ must not involve one’s being justified in believing or in ‘presupposing’ any falsehood, even if one’s reasoning to the belief does not employ that falsehood as a lemma. Alternatively, Roderick Chisholm (1989) requires that if there is something that makes the proposition that ‘h’ evident for one and yet makes something else that is false evident for one, then the proposition that ‘h’ is implied by a conjunction of propositions, each of which is evident for one and is such that something that makes it evident for one makes no falsehood evident for one. Other types of analyses are concerned with the role of falsehoods within the justification of the proposition that ‘h’ (Versus the justification of one’s believing that ‘h’). Such a theory may require that one’s evidence bearing on this justification not already contain falsehoods. Or it may require that no falsehoods are involved at specific places in a special explanatory structure relating to the justification of the proposition that ‘h’ (Shope, 1983.).
 A frequently pursued line of research concerning a fourth condition of knowing seeks what is called a ‘defeasibility’ analysis of ‘PK.’ Early versions characterized defeasibility by means of subjunctive conditionals of the form, ‘If ‘A’ were the case then ‘B’ would be the case’. But more recently the label has been applied to conditions about evidential or justificational relations that are not themselves characterized in terms of conditionals. Early versions of defeasibility theories advanced conditionals where ‘A’ is a hypothetical situation concerning one’s acquisition of a specified sort of epistemic status for specified propositions, e.g., one’s acquiring justified belief in some further evidence or truths, and ‘B’; concerned, for instance, the continued justified status of the proposition that ‘h’ or of one’s believing that ‘h’.
 A unifying thread connecting the conditional and non-conditional approaches to defeasibility may lie in the following facts: (1) What is a reason for being in a propositional attitude is in part a consideration, instances of the thought of which have the power to affect relevant processes of propositional attitude formation?: (2) Philosophers have often hoped to analyse power ascriptions by means of conditional statements: And (3) Arguments portraying evidential or justificational relations are abstractions from those processes of propositional attitude maintenance and formation that manifest rationality. So even when some circumstance, ‘R’, is a reason for believing or accepting that ‘h’, another circumstance, ‘K’ may present an occasion from being present for a rational manifestation of the relevant power of the thought of ‘R’ and it will not be a good argument to base a conclusion that ‘h’ on the premiss that ‘R’ and ‘K’ obtain. Whether ‘K’ does play this interfering, ‘defeating’. Role will depend upon the total relevant situation.
 Accordingly, one of the most sophisticated defeasibility accounts, which has been proposed by John Pollock (1986), requires that in order to know that ‘h’, one must believe that ‘h’ on the basis of an argument whose force is not defeated in the above way, given the total set of circumstances described by all truths. More specifically, Pollock defines defeat as a situation where (1) one believes that ‘p’ and it is logically possible for one to become justified in believing that ‘h’ by believing that ’p’, and (2) on e actually has a further set of beliefs, ‘S’ logically has a further set of beliefs, ‘S’, logically consistent with the proposition that ‘h’, such that it is not logically possible for one to become justified in believing that ‘h’ by believing it ion the basis of holding the set of beliefs that is the union of ‘S’ with the belief that ‘p’ (Pollock, 1986, pp. 36, 38). Furthermore, Pollock requires for ‘PK’ that the rational presupposition in favour of one’s believing that ‘h’ created by one’s believing that ‘p’ is undefeated by the set of all truths, including considerations that one does not actually believe. Pollock offers no definition of what this requirements means. But he may intend roughly the following: There ‘T’ is the set of all true propositions: (I) one believes that ‘p’ and it is logically possible for one to become justified in believing that ‘h’; by believing that ‘p’. And (II) there are logically possible situations in which one becomes justified in believing that ‘h’ on the bass of having the belief that ‘p’ and the beliefs in ‘T’ . Thus, in the Notgot example, since ‘T’ includes the proposition that Mr. Notgot does own a Ford, one lack’s knowledge because condition (II) is not satisfied.
 But given such an interpretation. Pollock’s account illustrates the fact that defeasibility theories typically have difficulty dealing with introspective knowledge of one’s beliefs. Suppose that some proposition, say that ƒ, is false, but one does not realize this and holds the belief that ƒ. Condition
(II) has no knowledge that h2 ?: ‘I believe that ƒ’. At least this is so if one’s reason for believing that h2 includes the presence of the very condition of which one is aware, i.e., one’s believing that ƒ. It is incoherent to suppose hat one retains the latter reason, also, believes the truth that not-ƒ. This objection can be avoided, but at the cost of adopting what is a controversial view about introspective knowledge that ‘h’, namely, the view that one’s belief that ‘h’ is in such cases mediated by some mental state intervening between the mental state of which there is introspective knowledge and he belief that ‘h’, so that is mental state is rather than the introspected state that it is included in one’s reason for believing that ‘h’. In order to avoid adopting this controversial view, Paul Moser (1989) gas proposed a disjunctive analysis of ‘PK’, which requires that either one satisfy a defeasibility condition rather than like Pollock’s or else one believes that ‘h’ by introspection. However, Moser leaves obscure exactly why beliefs arrived at by introspections account as knowledge.
 Early versions of defeasibility theories had difficulty allowing for the existence of evidence that is ‘merely misleading’, as in the case where one does know that ‘h3: ‘Tom Grabit stole a book from the library’, thanks to having seen him steal it, yet where, unbeknown to oneself, Tom’s mother out of dementia gas testified that Tom was far away from the library at the time of the theft.  One’s justifiably believing that she gave the testimony would destroy one’s justification for believing that ‘h3' if added by itself to one’s present evidence.
 At least some defeasibility theories cannot deal with the knowledge one has while dying that ‘h4: ‘In this life there is no timer at which I believe that ‘d’, where the proposition that ‘d’ expresses the details regarding some philosophical matter, e.g., the maximum number of blades of grass ever simultaneously growing on the earth. When it just so happens that it is true that ‘d’, defeasibility analyses typically consider the addition to one’s dying thoughts of a belief that ‘d’ in such a way as to improperly rule out actual knowledge that ‘h4'.
 A quite different approach to knowledge, and one able to deal with some Gettier-type cases, involves developing some type of causal theory of Propositional knowledge. The interesting thesis that counts as a causal theory of justification (in the meaning of ‘causal theory; intended here) is the that of a belief is justified just in case it was produced by a type of process that is ‘globally’ reliable, that is, its propensity to produce true beliefs-that can be defined (to a god enough approximation) as the proportion of the bailiffs it produces (or would produce were it used as much as opportunity allows) that are true-is sufficiently meaningful-variations of this view have been advanced for both knowledge and justified belief. The first formulation of reliability account of knowing appeared in a note by F.P. Ramsey (1931), who said that a belief was knowledge if it is true, certain can obtain by a reliable process. P. Unger (1968) suggested that ‘S’ knows that ‘p’ just in case it is not at all accidental that ‘S’ is right about its being the casse that ‘p’. D.M. Armstrong (1973) said that a non-inferential belief qualified as knowledge if the belief has properties that are nominally sufficient for its truth, i.e., guarantee its truth through and by the laws of nature.
 Such theories require that one or another specified relation hold that can be characterized by mention of some aspect of cassation concerning one’s belief that ‘h’ (or one’s acceptance of the proposition that ‘h’) and its relation to state of affairs ‘h*’, e.g., h* causes the belief: h* is causally sufficient for the belief h* and the belief have a common cause. Such simple versions of a causal theory are able to deal with the original Notgot case, since it involves no such causal relationship, but cannot explain why there is ignorance in the variants where Notgot and Berent Enç (1984) have pointed out that sometimes one knows of ‘χ’, that is ø thanks to recognizing a feature merely corelated with the presence of oness without endorsing a causal theory themselves, there suggest that it would need to be elaborated so as to allow that one’s belief that ‘χ’ has ø has been caused by a factor whose correlation with the presence of oness has caused in oneself, e.g., by evolutionary adaption in one’s ancestors, the disposition that one manifests in acquiring the belief in response to the correlated factor. Not only does this strain the unity of as causal theory by complicating it, but no causal theory without other shortcomings has been able to cover instances of deductively reasoned knowledge.
 Causal theories of Propositional knowledge differ over whether they deviate from the tripartite analysis by dropping the requirements that one’s believing (accepting) that ‘h’ be justified. The same variation occurs regarding reliability theories, which present the Knower as reliable concerning the issue of whether or not ‘h’, in the sense that some of one’s cognitive or epistemic states, θ, are such that, given further characteristics of oneself-possibly including relations to factors external to one and which one may not be aware-it is nomologically necessary (or at least probable) that ‘h’. In some versions, the reliability is required to be ‘global’ in as far as it must concern a nomologically (probabilistic) relationship) relationship of states of type θ to the acquisition of true beliefs about a wider range of issues than merely whether or not ‘h’. There is also controversy about how to delineate the limits of what constitutes a type of relevant personal state or characteristic. (For example, in a case where Mr Notgot has not been shamming and one does know thereby that someone in the office owns a Ford, such as a way of forming beliefs about the properties of persons spatially close to one, or instead something narrower, such as a way of forming beliefs about Ford owners in offices partly upon the basis of their relevant testimony?)
 One important variety of reliability theory is a conclusive reason account, which includes a requirement that one’s reasons for believing that ‘h’ be such that in one’s circumstances, if h* were not to occur then, e.g., one would not have the reasons one does for believing that ‘h’, or, e.g., one would not believe that ‘h’. Roughly, the latter is demanded by theories that treat a Knower as ‘tracking the truth’, theories that include the further demand that is roughly, if it were the case, that ‘h’, then one would believe that ‘h’. A version of the tracking theory has been defended by Robert Nozick (1981), who adds that if what he calls a ‘method’ has been used to arrive at the belief that ‘h’, then the antecedent clauses of the two conditionals that characterize tracking will need to include the hypothesis that one would employ the very same method.
 But unless more conditions are added to Nozick’s analysis, it will be too weak to explain why one lack’s knowledge in a version of the last variant of the tricky Mr Notgot case described above, where we add the following details: (a) Mr Notgot’s compulsion is not easily changed, (b) while in the office, Mr Notgot has no other easy trick of the relevant type to play on one, and ©) one arrives at one’s belief that ‘h’, not by reasoning through a false belief ut by basing belief that ‘h’, upon a true existential generalization of one’s evidence.
 Nozick’s analysis is in addition too strong to permit anyone ever to know that ‘h’: ‘Some of my beliefs about beliefs might be otherwise, e.g., I might have rejected on of them’.  If I know that ‘h5' then satisfaction of the antecedent of one of Nozick’s conditionals would involve its being false that ‘h5', thereby thwarting satisfaction of the consequent’s requirement that I not then believe that ‘h5'. For the belief that ‘h5' is itself one of my beliefs about beliefs (Shope, 1984).
 Some philosophers think that the category of knowing for which true. Justified believing (accepting) is a requirement constituting only a species of Propositional knowledge, construed as an even broader category. They have proposed various examples of ‘PK’ that do not satisfy the belief and/ort justification conditions of the tripartite analysis. Such cases are often recognized by analyses of Propositional knowledge in terms of powers, capacities, or abilities. For instance, Alan R. White (1982) treats ‘PK’ as merely the ability to provide a correct answer to a possible questions, however, White may be equating ‘producing’ knowledge in the sense of producing ‘the correct answer to a possible question’ with ‘displaying’ knowledge in the sense of manifesting knowledge. (White, 1982). The latter can be done even by very young children and some non-human animals independently of their being asked questions, understanding questions, or recognizing answers to questions. Indeed, an example that has been proposed as an instance of knowing that ‘h’ without believing or accepting that ‘h’ can be modified so as to illustrate this point. Two examples concerns an imaginary person who has no special training or information about horses or racing, but who in an experiment persistently and correctly picks the winners of upcoming horseraces. If the example is modified so that the hypothetical ‘seer’ never picks winners but only muses over whether those horses wight win, or only reports those horses winning, this behaviour should be as much of a candidate for the person’s manifesting knowledge that the horse in question will win as would be the behaviour of picking it as a winner.
 These considerations expose limitations in Edward Craig’s analysis (1990) of the concept of knowing of a person’s being a satisfactory informant in relation to an inquirer who wants to find out whether or not ‘h’. Craig realizes that counterexamples to his analysis appear to be constituted by Knower who are too recalcitrant to inform the inquirer, or too incapacitate to inform, or too discredited to be worth considering (as with the boy who cried ‘Wolf’). Craig admits that this might make preferable some alternative view of knowledge as a different state that helps to explain the presence of the state of being a suitable informant when the latter does obtain. Such the alternate, which offers a recursive definition that concerns one’s having the power to proceed in a way representing the state of affairs, causally involved in one’s proceeding in this way. When combined with a suitable analysis of representing, this theory of propositional knowledge can be unified with a structurally similar analysis of knowing how to do something.
 Knowledge and belief, according to most epistemologists, knowledge entails belief, so that I cannot know that such and such is the case unless I believe that such and such is the case. Others think this entailment thesis can be rendered more accurately if we substitute for belief some closely related attitude. For instance, several philosophers would prefer to say that knowledge entail psychological certainties (Prichard, 1950 and Ayer, 1956) or conviction (Lehrer, 1974) or acceptance (Lehrer, 1989). None the less, there are arguments against all versions of the thesis that knowledge requires having a belief-like attitude toward the known. These arguments are given by philosophers who think that knowledge and belief (or a facsimile) are mutually incompatible (the incomparability thesis), or by ones who say that knowledge does not entail belief, or vice versa, so that each may exist without the other, but the two may also coexist (the separability thesis).
 The incompatibility thesis is sometimes traced to Plato ©. 429-347 BC) in view of his claim that knowledge is infallible while belief or opinion is fallible (‘Republic’ 476-9). But this claim would not support the thesis. Belief might be a component of an infallible form of knowledge in spite of the fallibility of belief. Perhaps, knowledge involves some factor that compensates for the fallibility of belief.
 A. Duncan-Jones (1939: Also Vendler, 1978) cite linguistic evidence to back up the incompatibility thesis. He notes that people often say ‘I do not believe she is guilty. I know she is’ and the like, which suggest that belief rule out knowledge. However, as Lehrer (1974) indicates, the above exclamation is only a more emphatic way of saying ‘I do not just believe she is guilty, I know she is’ where ‘just’ makes it especially clear that the speaker is signalling that she has something more salient than mere belief, not that she has something inconsistent with belief, namely knowledge. Compare: ‘You do not hurt him, you killed him’.
 A. Prichard (1966) offers a defence of the incompatibility thesis that hinges on the equation of knowledge with certainty (both infallibility and psychological certitude) and the assumption that when we believe in the truth of a claim we are not certain about its truth. Given that belief always involves uncertainty while knowledge never dies, believing something rules out the possibility of knowing it. Unfortunately, however, Prichard gives ‘us’ no goods reason to grant that states of belief are never ones involving confidence. Conscious beliefs clearly involve some level of confidence, to suggest that we cease to believe things about which we are completely confident is bizarre.
 A.D. Woozley (1953) defends a version of the separability thesis. Woozley’s version, which deals with psychological certainty rather than belief per se, is that knowledge can exist in the absence of confidence about the item known, although might also be accompanied by confidence as well. Woozley remarks that the test of whether I know something is ‘what I can do, where what I can do may include answering questions’. On the basis of this remark he suggests that even when people are unsure of the truth of a claim, they might know that the claim is true. We unhesitatingly attribute knowledge to people who give correct responses on examinations even if those people show no confidence in their answers. Woozley acknowledges, however, that it would be odd for those who lack confidence to claim knowledge. It would be peculiar to say, ‘I am unsure whether my answer is true: Still, I know it is correct’. But this tension Woozley explains using a distinction between conditions under which we are justified in making a claim (such as a claim to know something), and conditions under which the claim we make is true. While ‘I know such and such’ might be true even if I am unsure whether such and such holds, nonetheless it would be inappropriate for me to claim that I know that such and such unless I were sure of the truth of my claim.
 Colin Radford (1966) extends Woozley’s defence of the separability thesis. In Radford’s view, not only is knowledge compatible with the lack of certainty, it is also compatible with a complete lack of belief. He argues by example. In one example, Jean has forgotten that he learned some English history year’s priori and yet he is able to give several correct responses to questions such as ‘When did the Battle of Hastings occur’? Since he forgot that he took history, he considers the correct response to be no more than guesses. Thus, when he says that the Battle of Hastings took place in 1066 he would deny having the belief that the Battle of Hastings took place in 1066. A disposition he would deny being responsible (or having the right to be convincing) that 1066 was the correct date. Radford would none the less insist that Jean know when the Battle occurred, since clearly be remembering the correct date. Radford admits that it would be inappropriate for Jean to say that he knew when the Battle of Hastings occurred, but, like Woozley he attributes the impropriety to a fact about when it is and is not appropriate to claim knowledge. When we claim knowledge, we ought, at least to believe that we have the knowledge we claim, or else our behaviour is ‘intentionally misleading’.
 Those that agree with Radford’s defence of the separability thesis will probably think of belief as an inner state that can be detected through introspection. That Jean lack’s beliefs about English history is plausible on this Cartesian picture since Jean does not find himself with any beliefs about English history when ne seek them out. One might criticize Radford, however, by rejecting that Cartesian view of belief. One could argue that some beliefs are thoroughly unconscious, for example. Or one could adopt a behaviourist conception of belief, such as Alexander Bain’s (1859), according to which having beliefs is a matter of the way people are disposed to behave (and has not Radford already adopted a behaviourist conception of knowledge?) Since Jean gives the correct response when queried, a form of verbal behaviour, a behaviourist would be tempted to credit him with the belief that the Battle of Hastings occurred in 1066.
 D.M. Armstrong (1873) takes a different tack against Radford. Jean does know that the Battle of Hastings took place in 1066. Armstrong will grant Radfod that point, in fact, Armstrong suggests that Jean believe that 1066 is not the date the Battle of Hastings occurred, for Armstrong equates the belief that such and such is just possible but no more than just possible with the belief that such and such is not the case. However, Armstrong insists, Jean also believes that the Battle did occur in 1066. After all, had Jean been mistaught that the Battle occurred in 1066, and subsequently ‘guessed’ that it took place in 1066, we would surely describe the situation as one in which Jean’s false belief about the Battle became unconscious over time but persisted of a memory trace that was causally responsible for his guess. Out of consistency, we must describe Radford’s original case as one that Jean’s true belief became unconscious but persisted long enough to cause his guess. Thus, while Jean consciously believes that the Battle did not occur in 1066, unconsciously he does believe it occurred in 1066. So after all, Radford does not have a counterexample to the claim that knowledge entails belief.
 Armstrong’s response to Radford was to reject Radford’s claim that the examinee lacked the relevant belief about English history. Another response is to argue that the examinee lacks the knowledge Radford attributes to him (cf. Sorenson, 1982). If Armstrong is correct in suggesting that Jean believes both that 1066 is and that it is not the date of the Battle of Hastings, one might deny Jean knowledge on the grounds that people who believe the denial of what they believe cannot be said t know the truth of their belief. Another strategy might be to compare the examine case with examples of ignorance given in recent attacks on externalist accounts of knowledge (needless to say.  Externalists themselves would tend not to favour this strategy). Consider the following case developed by BonJour (1985): For no apparent reason, Samantha believes that she is clairvoyant. Again, for no apparent reason, she one day comes to believe that the President is in New York City, even though she has every reason to believe that the President is in Washington, D.C. In fact, Samantha is a completely reliable clairvoyant, and she has arrived at her belief about the whereabouts of the President thorough the power of her clairvoyance. Yet surely Samantha’s belief is completely irrational. She is not justified in thinking what she does. If so, then she does not know where the President is. But Radford’s examinee is unconventional. Even if Jean lacks the belief that Radford denies him, Radford does not have an example of knowledge that is unattended with belief. Suppose that Jean’s memory had been sufficiently powerful to produce the relevant belief. As Radford says, in having every reason to suppose that his response is mere guesswork, and he has every reason to consider his belief false. His belief would be an irrational one, and hence one about whose truth Jean would be ignorant.
 Least has been of mention to an approaching view from which ‘perception’ basis upon itself as a fundamental philosophical topic both for its central place in ant theory of knowledge, and its central place un any theory of consciousness. Philosophy in this area is constrained by a number of properties that we believe to hold of perception, (1) It gives ‘us’ knowledge of the world around ‘us’. (2) We are conscious of that world by being aware of ‘sensible qualities’: Colour, sounds, tastes, smells, felt warmth, and the shapes and positions of objects in the environment. (3) Such consciousness is effected through highly complex information channels, such as the output of the three different types of colour-sensitive cells in the eye, or the channels in the ear for interpreting pulses of air pressure as frequencies of sound. (4) There ensues even more complex neurophysiological coding of that information, and eventually higher-order brain functions bring it about that we interpreted the information so received. (Much of this complexity has been revealed by the difficulties of writing programs enabling computers to recognize quite simple aspects of the visual scene.) The problem is to avoid thinking of here being a central, ghostly, conscious self, fed information in the same way that a screen if fed information by a remote television camera. Once such a model is in place, experience will seem like a veil getting between ‘us’ and the world, and the direct objects of perception will seem to be private items in an inner theatre or sensorium. The difficulty of avoiding this model is epically cute when we considered the secondary qualities of colour, sound, tactile feelings and taste, which can easily seem to have a purely private existence inside the perceiver, like sensation of pain. Calling such supposed items names like ‘sense-data’ or ‘percepts’ exacerbates the tendency, but once the model is in place, the first property, that perception gives ‘us’ knowledge of the world and its surrounding surfaces, is quickly threatened, for there will now seem little connection between these items in immediate experience and any independent reality. Reactions to this problem include ‘scepticism’ and ‘idealism’.
 A more hopeful approach is to claim that the complexities of (3) and (4) explain how we can have direct acquaintance of the world, than suggesting that the acquaintance we do have been at best indirect. It is pointed out that perceptions are not like sensation, precisely because they have a content, or outer-directed nature. To have a perception is to be aware of the world for being such-and-such a way, than to enjoy a mere modification of sensation. But such direct realism has to be sustained in the face of the evident personal (neurophysiological and other) factors determining haw we perceive. One approach is to ask why it is useful to be conscious of what we perceive, when other aspects of our functioning work with information determining responses without any conscious awareness or intervention. A solution to this problem would offer the hope of making consciousness part of the natural world, than a strange optional extra.
 Furthering, perceptual knowledge is knowledge acquired by or through the senses and includes most of what we know. We cross intersections when we see the light turn green, head for the kitchen when we smell the roast burning, squeeze the fruit to determine its ripeness, and climb out of bed when we hear the alarm ring. In each case we come to know something-that the light has turned green, that the roast is burning, that the melon is overripe, and that it is time to get up-by some sensory means. Seeing that the light has turned green is learning something-that, the light has turned green-by use of the eyes. Feeling that the melon is overripe is coming to know a fact-that the melon is overripe-by one’s sense to touch. In each case the resulting knowledge is somehow based on, derived from or grounded in the sort of experience that characterizes the sense modality in question.
 Much of our perceptual knowledge is indirect, dependent or derived. By this I mean that the facts we describe ourselves as learning, as coming to know, by perceptual means are pieces of knowledge that depend on our coming to know something else, some other fact, in a more direct way. We see, by the gauge, that we need gas, see, by the newspapers, that our team has lost again, see, by her expression, that she is nervous. This derived or dependent sort of knowledge is particularly prevalent in the cases of vision, but it occurs, to a lesser degree, in every sense modality. We install bells and other noise-makers so that we calm for example, hear (by the bell) that someone is at the door and (by the alarm) that its time to get up. When we obtain knowledge in this way, it is clear that unless one sees-hence, comes to know something about the gauge (that it says) and (hence, know) that one is described as coming to know by perceptual means. If one cannot hear that the bell is ringing, one cannot-in at least in this way-hear that one’s visitors have arrived. In such cases one sees (hears, smells, etc.) that ‘a’ is ‘F’, coming to know thereby that ‘a’ is ‘F’, by seeing (hearing, etc.) that some other condition, ‘b’s’ being ‘G’, obtains when this occurs, the knowledge (that ‘a’ is ‘F’) is derived from, or dependent on, the more basic perceptual knowledge that ‘b’ is ‘G’.
 Perhaps as a better strategy is to tie an account save that part that evidence could justify explanation for it is its truth alone. Since, at least the time of Aristotle philosophers of explanatory knowledge have emphasizes of its importance that, in its simplest therms, we want to know not only what are the composite peculiarities and particulars points of issue but also why it is. This consideration suggests that we define an explanation as an answer to a why-question. Such a definition would, however, be too broad, because some why-questions are requests for consolation (Why did my son have to die?) Or moral justification (Why should women not be paid the same as men for the same work?) It would also be too narrow because some explanations are responses to how-questions (How does radar work?) Or how-possibility-questions (How is it possible for cats always to land their feet?)
 In its overall sense, ‘to explain’ means to make clear, to make plain, or to provide understanding. Definition of this sort are philosophically unhelpful, for the terms used in the deficient are no less problematic than the term to be defined. Moreover, since a wide variety of things require explanation, and since many different types of explanation exist, as more complex explanation is required. To facilitate the requirement leaves, least of mention, for us to consider by introduction a bit of technical terminology. The term ‘explanation’ is used to refer to that which is to be explained: The term ‘explanans’ refers to that which does the explaining, the explanans and the explanation taken together constitute the explanation.
 One common type of explanation occurs when deliberate human actions are explained in terms of conscious purposes. ‘Why did you go to the pharmacy yesterday?’ ‘Because I had a headache and needed to get some aspirin.’ It is tacitly assumed that aspirin is an appropriate medication for headaches and that going t the pharmacy would bean efficient way of getting some. Such explanations are, of course, teleological, referring, ss they do, to goals. The explanans is not the realisation of a future goal-if the pharmacy happened to be closed for stocktaking the aspirin would have ben obtained there, bu t that would not invalidate the explanation. Some philosophers would say that the antecedent desire to achieve the end is what doers the explaining: Others might say that the explaining is done by the nature of the goal and the fact that the action promoted the chances of realizing it. (Taylor, 1964). In that it should not be automatically be assumed that such explanations are causal. Philosophers differ considerably on whether these explanations are to be framed in terms of cause or reason, but the distinction cannot be used to show that the relation between reasons and the actions they justify is in no way causal, and there are many differing analyses of such concepts as intention and agency. Expanding the domain beyond consciousness, Freud maintained, in addition, that much human behaviour can be explained in terms of unconscious and conscious wishes. Those Freudian explanations should probably be construed as basically causal.
 Problems arise when teleological explanations are offered in other context. The behaviour of non-human animals is often explained in terms of purpose, e.g., the mouse ran to escape from the cat. In such cases the existence of conscious purpose seems dubious. The situation is still more problematic when a supr-empirical purpose in invoked -, e.g., the explanations of living species in terms of God’s purpose, or the vitalistic explanations of biological phenomena in terms of a entelechy or vital principle. In recent years an ‘anthropic principle’ has received attention in cosmology (Barrow and Tipler, 1986). All such explanations have been condemned by many philosophers an anthropomorphic.
 Nevertheless, philosophers and scientists often maintain that functional explanations play an important an legitimate role in various sciences such as, evolutionary biology, anthropology and sociology. For example, of the peppered moth in Liverpool, the change in colour from the light phase to the dark phase and back again to the light phase provided adaption to a changing environment and fulfilled the function of reducing predation on the spacies. In the study of primitive soviets anthropologists have maintained that various rituals the (rain dance) which may be inefficacious in braining about their manifest gaols (producing rain), actually cohesion at a period of stress (often a drought). Philosophers who admit teleological and/or functional explanations in common sense and science oftentimes take pans to argue that such explanations can be annualized entirely in terms of efficient causes, thereby escaping the charge of anthropomorphism (Wright, 1976): Again, however, not all philosophers agree.
 Mainly to avoid the incursion of unwanted theology, metaphysics, or anthropomorphism into science, many philosophers and scientists, especially during the first half of the twentieth century-held that science provides only descriptions and predictions of natural phenomena, but not explanations for a series of influential philosophers of science-including Karl Popper (1935) Carl Hempel and Paul Oppenheim (1948) and Hempel (1965)-maintained that empirical science can explain natural phenomena without appealing to metaphysics or theology. It appears that this view is now accepted by the vast majority of philosophers of science, though there is sharp disagreement on the nature of scientific explanation.
 The foregoing approach, developed by Hempel, Popper and others, became virtually a ‘received view’ in the 1960s and 1970s. According to this view, to give a scientific explanation of any natural phenomenon is to show how this phenomena can be subsumed under a law of nature. A particular repture in a water pipe can be explained by citing the universal law that water expands when it freezes and the fact that the temperature of water in a pipe dropped below the freezing point. General law, as well as particular facts, can be explained by subsumption, the law of conservation of linear momentum can be explained by derivation from Newton’s second and third laws of motion. Each of these explanations is a deductive argument: The explanans contains one or more statements of universal laws and, in many cases, statements deceiving initial conditions. This pattern of explanation is known as the deductive-nomological (D-N) model. Any such argument shows that the explanandun had to occur given the explanans.
 Many, though not all, adherents of the received view allow for explanation by subsumption under statistical laws. Hempel (1965) offers as an example the case of a man who recovered quickly from a streptococcus infection as a result of treatment with penicillin. Although not all strep infections’ clar up quickly under this treatment, the probability of recovery in such cases is high, and this is sufficient for legitimate explanation According to Hempel. This example conforms to the inductive-statistical (I-S) model. Such explanations are viewed as arguments, but they are inductive than deductive. In these instances the explanation confers high inductive probability on the explanandum. An explanation of a particular fact satisfying either the D-N or I-S model is an argument to the effect that the fact in question was to b e expected by virtue of the explanans.
 The received view been subjected to strenuous criticism by adherents of the causal/mechanical approach to scientific explanation (Salmon 1990). Many objections to the received view we engendered by he absence of caudal constraints (due largely to worries about Hume’s critique) on the N-D and I-S models. Beginning in the late 1950s, Michael Scriven advanced serious counter-examples to Hempel’s models: He was followed in the 1960s by Wesley Salmon and in the 1970s by Peter Railton. As accorded to the view, one explains phenomena identifying causes (a death is explained resalting from a massive cerebral haemorrhage) or by exposing underlying mechanisms (the behaviour of a gas is explained in terms of the motion of constituent molecules).
 A unification approach to explanation carries with the basic idea that we understand our world more adequately to the extent that we can reduce the number of independent assumptions we must introduce to account for what goes on in it. Accordingly, we understand phenomena to the degree that we can fit them into an overall world picture or Weltanschauung. In order to serve in scientific explanation, the world picture must be scientifically well founded.
 During the pas half-century much philosophical attention has ben focussed on explanation in science and in history. Considerable controversy has surrounded the question of whether historical explanation must be scientific, or whether history requires explanations of different types. Many diverse views have been articulated: The forgoing brief survey does not exhaust the variety (Salmon, 19990).
 In everyday life we encounter many types of explanation, which appear not to raise philosophical difficulties, in addition to those already made of mention. Prior to take-off a flight attendant explains how to use the safety equipment on the aero-plane. In a museum the guide explain the significance of a famous painting. A mathematics teacher explains a geometrical proof to a bewildered student. A newspaper story explains how a prisoner escaped. Additional examples come easily to mind, the main point is to remember the great variety of contexts in which explanations are sought and given into.
 Another item of importance to epistemology is the wider held notion that non-demonstrative inferences can be characterized as inference to the best explanation. Given the variety of views on the nature of explanation, this popular slogan can hardly provide a useful philosophical analysis
Early versions of defeasibility theories had difficulty allowing for the existence of evidence that was ‘merely misleading,’ as in the case where one does know that h3: ‘Tom Grabit stole a book from the library,’ thanks to having seen him steal it, yet where, unbeknown to oneself, Tom’s mother out of dementia gas testified that Tom was far away from the library at the time of the theft.  One’s justifiably believing that she gave the testimony would destroy one’s justification for believing that h3' if added by itself to one’s present evidence.
 At least some defeasibility theories cannot deal with the knowledge one has while dying that h4: ‘In this life there is no timer at which I believe that ‘d’, where the proposition that 'd' expresses the details regarding some philosophical matter, e.g., the maximum number of blades of grass ever simultaneously growing on the earth. When it just so happens that it is true that ‘d’, defeasibility analyses typically consider the addition to one’s dying thoughts of a belief that ‘d’ in such a way as to improperly rule out actual knowledge that ‘h4'.
 A quite different approach to knowledge, and one able to deal with some Gettier-type cases, involves developing some type of causal theory of Propositional knowledge. The interesting thesis that counts as a causal theory of justification (in the meaning of ‘causal theory’: Intended here) is the that of a belief is justified just in case it was produced by a type of process that is ‘globally’ reliable, that is, its propensity to produce true beliefs-that can be defined (to a god enough approximation) as the proportion of the bailiffs it produces (or would produce where it used as much as opportunity allows) that are true-is sufficiently meaningful-variations of this view have been advanced for both knowledge and justified belief. The first formulation of reliability account of knowing appeared in a note by F.P. Ramsey (1931), who said that a belief was knowledge if it is true, certain can obtain by a reliable process. P. Unger (1968) suggested that 'S’ knows that ‘p’ just in case it is not at all accidental that ‘S’ is right about its being the casse that ‘p’. D.M. Armstrong (1973) said that a non-inferential belief qualified as knowledge if the belief has properties that are nominally sufficient for its truth, i.e., guarantee its truth through and by the laws of nature.
 Such theories require that one or another specified relation hold that can be characterized by mention of some aspect of cassation concerning one’s belief that ‘h’ (or one’s acceptance of the proposition that ‘h’) and its relation to state of affairs ‘h*’, e.g., 'h' causes the belief: 'h' is causally sufficient for the belief 'h' and the belief have a common cause. Such simple versions of a causal theory are able to deal with the original Notgot case, since it involves no such causal relationship, but cannot explain why there is ignorance in the variants where Notgot and Berent Enç (1984) have pointed out that sometimes one knows of ‘χ’ that is ø thanks to recognizing a feature merely corelated with the presence of oness without endorsing a causal theory themselves, there suggest that it would need to be elaborated so as to allow that one’s belief that ‘χ’ has ø has been caused by a factor whose correlation with the presence of oness has caused in oneself, e.g., by evolutionary adaption in one’s ancestors, the disposition that one manifests in acquiring the belief in response to the correlated factor. Not only does this strain the unity of as causal theory by complicating it, but no causal theory without other shortcomings has been able to cover instances of deductively reasoned knowledge.
 Causal theories of Propositional knowledge differ over whether they deviate from the tripartite analysis by dropping the requirements that one’s believing (accepting) that ‘h’ be justified. The same variation occurs regarding reliability theories, which present the Knower as reliable concerning the issue of whether or not ‘h’, in the sense that some of one’s cognitive or epistemic states, θ, are such that, given further characteristics of oneself-possibly including relations to factors external to one and which one may not be aware-it is nomologically necessary (or at least probable) that ‘h’. In some versions, the reliability is required to be ‘global’ in as far as it must concern a nomologically (probabilistic) relationship) relationship of states of type θ to the acquisition of true beliefs about a wider range of issues than merely whether or not ‘h’. There is also controversy about how to delineate the limits of what constitutes a type of relevant personal state or characteristic. (For example, in a case where Mr Notgot has not been shamming and one does know thereby that someone in the office owns a Ford, such as a way of forming beliefs about the properties of persons spatially close to one, or instead something narrower, such as a way of forming beliefs about Ford owners in offices partly upon the basis of their relevant testimony?)
 One important variety of reliability theory is a conclusive reason account, which includes a requirement that one’s reasons for believing that ‘h’ be such that in one’s circumstances, if h* were not to occur then, e.g., one would not have the reasons one does for believing that ‘h’, or, e.g., one would not believe that ‘h’. Roughly, the latter is demanded by theories that treat a Knower as ‘tracking the truth’, theories that include the further demand that is roughly, if it were the case, that ‘h’, then one would believe that ‘h’. A version of the tracking theory has been defended by Robert Nozick (1981), who adds that if what he calls a ‘method’ has been used to arrive at the belief that ‘h’, then the antecedent clauses of the two conditionals that characterize tracking will need to include the hypothesis that one would employ the very same method.
 But unless more conditions are added to Nozick’s analysis, it will be too weak to explain why one lack’s knowledge in a version of the last variant of the tricky Mr Notgot case described above, where we add the following details: (a) Mr Notgot’s compulsion is not easily changed, (b) while in the office, Mr Notgot has no other easy trick of the relevant type to play on one, and finally for one’s belief that ‘h’, not by reasoning through a false belief ut by basing belief that ‘h’, upon a true existential generalization of one’s evidence.
 Nozick’s analysis is in addition too strong to permit anyone ever to know that ‘h’: ‘Some of my beliefs about beliefs might be otherwise, e.g., I might have rejected on of them’. If I know that ‘h5' then satisfaction of the antecedent of one of Nozick’s conditionals would involve its being false that ‘h5', thereby thwarting satisfaction of the consequent’s requirement that I not then believe that ‘h5'. For the belief that ‘h5' is itself one of my beliefs about beliefs (Shope, 1984).
 Some philosophers think that the category of knowing for which is true. Justified believing (accepting) is a requirement constituting only a species of Propositional knowledge, construed as an even broader category. They have proposed various examples of ‘PK’ that do not satisfy the belief and/ort justification conditions of the tripartite analysis. Such cases are often recognized by analyses of Propositional knowledge in terms of powers, capacities, or abilities. For instance, Alan R. White (1982) treats ‘PK’ as merely the ability to provide a correct answer to a possible questions, however, White may be equating ‘producing’ knowledge in the sense of producing ‘the correct answer to a possible question’ with ‘displaying’ knowledge in the sense of manifesting knowledge. (White, 1982). The latter can be done even by very young children and some non-human animals independently of their being asked questions, understanding questions, or recognizing answers to questions. Indeed, an example that has been proposed as an instance of knowing that ‘h’ without believing or accepting that ‘h’ can be modified so as to illustrate this point. Two examples concerns an imaginary person who has no special training or information about horses or racing, but who in an experiment persistently and correctly picks the winners of upcoming horseraces. If the example is modified so that the hypothetical ‘seer’ never picks winners but only muses over whether those horses wight win, or only reports those horses winning, this behaviour should be as much of a candidate for the person’s manifesting knowledge that the horse in question will win as would be the behaviour of picking it as a winner.
 These considerations now placed upon our table, least that we take to consider of their vulnerability, that is in regard to their limitation: Edward Craig’s analysis (1990) of the concept of knowing of a person’s being a satisfactory informant in relation to an inquirer who wants to find out whether or not ‘h’. Craig realizes that counterexamples to his analysis appear to be constituted by Knower who are too recalcitrant to inform the inquirer, or too incapacitate to inform, or too discredited to be worth considering (as with the boy who cried ‘Wolf’). Craig admits that this might make preferable some alternative view of knowledge as a different state that helps to explain the presence of the state of being a suitable informant when the latter does obtain. Such the alternate, which offers a recursive definition that concerns one’s having the power to proceed in a way representing the state of affairs, causally involved in one’s proceeding in this way. When combined with a suitable analysis of representing, this theory of propositional knowledge can be unified with a structurally similar analysis of knowing how to do something.
 Knowledge and belief, according to most epistemologists, knowledge entails belief, so that I cannot know that such and such is the case unless I believe that such and such is the case. Others think this entailment thesis can be rendered more accurately if we substitute for belief some closely related attitude. For instance, several philosophers would prefer to say that knowledge entail psychological certainties (Prichard, 1950 and Ayer, 1956) or conviction (Lehrer, 1974) or acceptance (Lehrer, 1989). None the less, there are arguments against all versions of the thesis that knowledge requires having a belief-like attitude toward the known. These arguments are given by philosophers who think that knowledge and belief (or a facsimile) are mutually incompatible (the incomparability thesis), or by ones who say that knowledge does not entail belief, or vice versa, so that each may exist without the other, but the two may also coexist (the separability thesis).
 The incompatibility thesis is sometimes traced to Plato (429-347 Bc) in view of his claim that knowledge is infallible while belief or opinion is fallible (‘Republic’ 476-9). But this claim would not support the thesis. Belief might be a component of an infallible form of knowledge in spite of the fallibility of belief. Perhaps, knowledge involves some factor that compensates for the fallibility of belief.
 A. Duncan-Jones (1939: Also Vendler, 1978) cite linguistic evidence to back up the incompatibility thesis. He notes that people often say ‘I do not believe she is guilty. I know she is’ and the like, which suggest that belief rule out knowledge. However, as Lehrer (1974) indicates, the above exclamation is only a more emphatic way of saying ‘I do not just believe she is guilty, I know she is’ where ‘just’ makes it especially clear that the speaker is signalling that she has something more salient than mere belief, not that she has something inconsistent with belief, namely knowledge. Compare: ‘You do not hurt him, you killed him.'
 H.A. Prichard (1966) offers a defence of the incompatibility thesis that hinges on the equation of knowledge with certainty (both infallibility and psychological certitude) and the assumption that when we believe in the truth of a claim we are not certain about its truth. Given that belief always involves uncertainty while knowledge never dies, believing something rules out the possibility of knowing it. Unfortunately, however, Prichard gives ‘us’ no goods reason to grant that states of belief are never ones involving confidence. Conscious beliefs clearly involve some level of confidence, to suggest that we cease to believe things about which we are completely confident is bizarre.
 A.D. Woozley (1953) defends a version of the separability thesis. Woozley’s version, which deals with psychological certainty rather than belief per se, is that knowledge can exist in the absence of confidence about the item known, although might also be accompanied by confidence as well. Woozley remarks that the test of whether I know something is ‘what I can do, where what I can do may include answering questions.’ On the basis of this remark he suggests that even when people are unsure of the truth of a claim, they might know that the claim is true. We unhesitatingly attribute knowledge to people who give correct responses on examinations even if those people show no confidence in their answers. Woozley acknowledges, however, that it would be odd for those who lack confidence to claim knowledge. It would be peculiar to say, I am unsure whether my answer is true: Still, I know it is correct But this tension Woozley explains using a distinction between conditions under which we are justified in making a claim (such as a claim to know something), and conditions under which the claim we make is true. While ‘I know such and such’ might be true even if I am unsure whether such and such holds, nonetheless it would be inappropriate for me to claim that I know that such and such unless I were sure of the truth of my claim.
 Colin Radford (1966) extends Woozley’s defence of the separability thesis. In Radford’s view, not only is knowledge compatible with the lack of certainty, it is also compatible with a complete lack of belief. He argues by example. In one example, Jean has forgotten that he learned some English history year’s priori and yet he is able to give several correct responses to questions such as ‘When did the Battle of Hastings occur?’ Since he forgot that he took history, he considers the correct response to be no more than guesses. Thus, when he says that the Battle of Hastings took place in 1066 he would deny having the belief that the Battle of Hastings took place in 1066. A disposition he would deny being responsible (or having the right to be convincing) that 1066 was the correct date. Radford would none the less insist that Jean know when the Battle occurred, since clearly be remembering the correct date. Radford admits that it would be inappropriate for Jean to say that he knew when the Battle of Hastings occurred, but, like Woozley he attributes the impropriety to a fact about when it is and is not appropriate to claim knowledge. When we claim knowledge, we ought, at least to believe that we have the knowledge we claim, or else our behaviour is ‘intentionally misleading’.
 Those that agree with Radford’s defence of the separability thesis will probably think of belief as an inner state that can be detected through introspection. That Jean lack’s beliefs about English history is plausible on this Cartesian picture since Jean does not find himself with any beliefs about English history when ne seek them out. One might criticize Radford, however, by rejecting that Cartesian view of belief. One could argue that some beliefs are thoroughly unconscious, for example. Or one could adopt a behaviourist conception of belief, such as Alexander Bain’s (1859), according to which having beliefs is a matter of the way people are disposed to behave (and has not Radford already adopted a behaviourist conception of knowledge?) Since Jean gives the correct response when queried, a form of verbal behaviour, a behaviourist would be tempted to credit him with the belief that the Battle of Hastings occurred in 1066.
 D.M. Armstrong (1873) takes a different tack against Radford. Jean does know that the Battle of Hastings took place in 1066. Armstrong will grant Radfod that point, in fact, Armstrong suggests that Jean believe that 1066 is not the date the Battle of Hastings occurred, for Armstrong equates the belief that such and such is just possible but no more than just possible with the belief that such and such is not the case. However, Armstrong insists, Jean also believes that the Battle did occur in 1066. After all, had Jean been mistaught that the Battle occurred in 1066, and subsequently ‘guessed’ that it took place in 1066, we would surely describe the situation as one in which Jean’s false belief about the Battle became unconscious over time but persisted of a memory trace that was causally responsible for his guess. Out of consistency, we must describe Radford’s original case as one that Jean’s true belief became unconscious but persisted long enough to cause his guess. Thus, while Jean consciously believes that the Battle did not occur in 1066, unconsciously he does believe it occurred in 1066. So after all, Radford does not have a counterexample to the claim that knowledge entails belief.
 Armstrong’s response to Radford was to reject Radford’s claim that the examinee lacked the relevant belief about English history. Another response is to argue that the examinee lacks the knowledge Radford attributes to him (cf. Sorenson, 1982). If Armstrong is correct in suggesting that Jean believes both that 1066 is and that it is not the date of the Battle of Hastings, one might deny Jean knowledge on the grounds that people who believe the denial of what they believe cannot be said t know the truth of their belief. Another strategy might be to compare the examine case with examples of ignorance given in recent attacks on externalist accounts of knowledge (needless to say.  Externalists themselves would tend not to favour this strategy). Consider the following case developed by BonJour (1985): For no apparent reason, Samantha believes that she is clairvoyant. Again, for no apparent reason, she one day comes to believe that the President is in New York City, even though she has every reason to believe that the President is in Washington, DC. In fact, Samantha is a completely reliable clairvoyant, and she has arrived at her belief about the whereabouts of the President thorough the power of her clairvoyance. Yet surely Samantha’s belief is completely irrational. She is not justified in thinking what she does. If so, then she does not know where the President is. But Radford’s examinee is unconventional. Even if Jean lacks the belief that Radford denies him, Radford does not have an example of knowledge that is unattended with belief. Suppose that Jean’s memory had been sufficiently powerful to produce the relevant belief. As Radford says, in having every reason to suppose that his response is mere guesswork, and he has every reason to consider his belief false. His belief would be an irrational one, and hence one about whose truth Jean would be ignorant.
 Least has been of mention to an approaching view from which ‘perception’ basis upon itself as a fundamental philosophical topic both for its central place in ant theory of knowledge, and its central place un any theory of consciousness. Philosophy in this area is constrained by a number of properties that we believe to hold of perception, (1) It gives ‘us’ knowledge of the world around ‘us,’ (2) We are conscious of that world by being aware of ‘sensible qualities’: Colour, sounds, tastes, smells, felt warmth, and the shapes and positions of objects in the environment. (3) Such consciousness is effected through highly complex information channels, such as the output of the three different types of colour-sensitive cells in the eye, or the channels in the ear for interpreting pulses of air pressure as frequencies of sound. (4) There ensues even more complex neurophysiological coding of that information, and eventually higher-order brain functions bring it about that we interpreted the information so received. (Much of this complexity has been revealed by the difficulties of writing programs enabling computers to recognize quite simple aspects of the visual scene.) The problem is to avoid thinking of here being a central, ghostly, conscious self, fed information in the same way that a screen if fed information by a remote television camera. Once such a model is in place, experience will seem like a veil getting between ‘us’ and the world, and the direct objects of perception will seem to be private items in an inner theatre or sensorium. The difficulty of avoiding this model is epically cute when we considered the secondary qualities of colour, sound, tactile feelings and taste, which can easily seem to have a purely private existence inside the perceiver, like sensation of pain. Calling such supposed items names like ‘sense-data’ or ‘percepts’ exacerbates the tendency, but once the model is in place, the first property, that perception gives ‘us’ knowledge of the world and its surrounding surfaces, is quickly threatened, for there will now seem little connection between these items in immediate experience and any independent reality. Reactions to this problem include ‘scepticism’ and ‘idealism.’
 A more hopeful approach is to claim that the complexities of (3) and (4) explain how we can have direct acquaintance of the world, than suggesting that the acquaintance we do have been at best indirect. It is pointed out that perceptions are not like sensation, precisely because they have a content, or outer-directed nature. To have a perception is to be aware of the world for being such-and-such a way, than to enjoy a mere modification of sensation. But such direct realism has to be sustained in the face of the evident personal (neurophysiological and other) factors determining haw we perceive. One approach is to ask why it is useful to be conscious of what we perceive, when other aspects of our functioning work with information determining responses without any conscious awareness or intervention. A solution to this problem would offer the hope of making consciousness part of the natural world, than a strange optional extra.
 Furthering, perceptual knowledge is knowledge acquired by or through the senses and includes most of what we know. We cross intersections when we see the light turn green, head for the kitchen when we smell the roast burning, squeeze the fruit to determine its ripeness, and climb out of bed when we hear the alarm ring. In each case we come to know something-that the light has turned green, that the roast is burning, that the melon is overripe, and that it is time to get up-by some sensory means. Seeing that the light has turned green is learning something-that the light has turned green-by use of the eyes. Feeling that the melon is overripe is coming to know a fact-that the melon is overripe-by one’s sense to touch. In each case the resulting knowledge is somehow based on, derived from or grounded in the sort of experience that characterizes the sense modality in question.
 Much of our perceptual knowledge is indirect, dependent or derived. By this I mean that the facts we describe ourselves as learning, as coming to know, by perceptual means are pieces of knowledge that depend on our coming to know something else, some other fact, in a more direct way. We see, by the gauge, that we need gas, see, by the newspapers, that our team has lost again, see, by her expression, that she is nervous. This derived or dependent sort of knowledge is particularly prevalent in the cases of vision, but it occurs, to a lesser degree, in every sense modality. We install bells and other noise-makers so that we calm for example, hear (by the bell) that someone is at the door and (by the alarm) that its time to get up. When we obtain knowledge in this way, it is clear that unless one sees-hence, comes to know something about the gauge (that it says) and (hence, know) that one is described as coming to know by perceptual means. If one cannot hear that the bell is ringing, one cannot-in at least in this way-hear that one’s visitors have arrived. In such cases one sees (hears, smells, etc.) that ‘a’ is ‘F’, coming to know thereby that ‘a’ is ‘F’, by seeing (hearing, etc.) that some other condition, ‘b’s’ being ‘G’, obtains when this occurs, the knowledge (that ‘a’ is ‘F’) is derived from, or dependent on, the more basic perceptual knowledge that ‘b’ is ‘G’.
 And finally, the representational Theory of mind (RTM) (which goes back at least to Aristotle) takes as its starting point commonsense mental states, such as thoughts, beliefs, desires, perceptions and images. Such states are said to have ‘intentionality’-they are about or refer to things, and may be evaluated with respect to properties like consistency, truth, appropriateness and accuracy. (For example, the thought that cousins are not related is inconsistent, the belief that Elvis is dead is true, the desire to eat the moon is inappropriate, a visual experience of a ripe strawberry as red is accurate, an image of George W. Bush with deadlocks is inaccurate.)
 The Representational Theory of Mind, defines such intentional mental states as relations to mental representations, and explains the intentionality of the former in terms of the semantic properties of the latter. For example, to believe that Elvis is dead is to be appropriately related to a mental representation whose propositional content is that Elvis is dead. (The desire that Elvis be dead, the fear that he is dead, the regret that he is dead, etc., involve different relations to the same mental representation.) To perceive a strawberry is to have a sensory experience of some kind which is appropriately related to (e.g., caused by) the strawberry Representational theory of mind also understands mental processes such as thinking, reasoning and imagining as sequences of intentional mental states. For example, to imagine the moon rising over a mountain is to entertain a series of mental images of the moon (and a mountain). To infer a proposition q from the propositions p and if 'p' then 'q' is (among other things) to have a sequence of thoughts of the form 'p', 'if p' then 'q', 'q'.
 Contemporary philosophers of mind have typically supposed (or at least hoped) that the mind can be naturalized-i.e., that all mental facts have explanations in the terms of natural science. This assumption is shared within cognitive science, which attempts to provide accounts of mental states and processes in terms (ultimately) of features of the brain and central nervous system. In the course of doing so, the various sub-disciplines of cognitive science (including cognitive and computational psychology and cognitive and computational neuroscience) postulate a number of different kinds of structures and processes, many of which are not directly implicated by mental states and processes as commonsensical conceived. There remains, however, a shared commitment to the idea that mental states and processes are to be explained in terms of mental representations.
 In philosophy, recent debates about mental representation have centred around the existence of propositional attitudes (beliefs, desires, etc.) and the determination of their contents (how they come to be about what they are about), and the existence of phenomenal properties and their relation to the content of thought and perceptual experience. Within cognitive science itself, the philosophically relevant debates have been focussed on the computational architecture of the brain and central nervous system, and the compatibility of scientific and commonsense accounts of mentality.
 Intentional Realists such as Dretske (e.g., 1988) and Fodor (e.g., 1987) note that the generalizations we apply in everyday life in predicting and explaining each other's behaviour (often collectively referred to as ‘folk psychology’) are both remarkably successful and indispensable. What a person believes, doubts, desires, fears, etc. is a highly reliable indicator of what that person will do; and we have no other way of making sense of each other's behaviour than by ascribing such states and applying the relevant generalizations. We are thus committed to the basic truth of commonsense psychology and, hence, to the existence of the states its generalizations refer to. (Some realists, such as Fodor, also hold that commonsense psychology will be vindicated by cognitive science, given that propositional attitudes can be construed as computational relations to mental representations.)
 Intentional Eliminativists, such as Churchland, (perhaps) Dennett and (at one time) Stich argue that no such things as propositional attitudes (and their constituent representational states) are implicated by the successful explanation and prediction of our mental lives and behaviour. Churchland denies that the generalizations of commonsense propositional-attitude psychology are true. He (1981) argues that folk psychology is a theory of the mind with a long history of failure and decline, and that it resists incorporation into the framework of modern scientific theories (including cognitive psychology). As such, it is comparable to alchemy and phlogiston theory, and ought to suffer a comparable fate. Commonsense psychology is false, and the states (and representations) it postulates simply don't exist. (It should be noted that Churchland is not an eliminativist about mental representation tout court.
 Dennett (1987) grants that the generalizations of commonsense psychology are true and indispensable, but denies that this is sufficient reason to believe in the entities they appear to refer to. He argues that to give an intentional explanation of a system's behaviour is merely to adopt the ‘intentional stance’ toward it. If the strategy of assigning contentful states to a system and predicting and explaining its behaviour (on the assumption that it is rational-i.e., that it behaves as it should, given the propositional attitudes it should have in its environment) is successful, then the system is intentional, and the propositional-attitude generalizations we apply to it are true. But there is nothing more to having a propositional attitude than this.
 Though he has been taken to be thus claiming that intentional explanations should be construed instrumentally, Dennett (1991) insists that he is a ‘moderate’ realist about propositional attitudes, since he believes that the patterns in the behaviour and behavioural dispositions of a system on the basis of which we (truly) attribute intentional states to it are objectively real. In the event that there are two or more explanatorily adequate but substantially different systems of intentional ascriptions to an individual, however, Dennett claims there is no fact of the matter about what the system believes (1987, 1991). This does suggest an irrealism at least with respect to the sorts of things Fodor and Dretske take beliefs to be; though it is not the view that there is simply nothing in the world that makes intentional explanations true.
 (Davidson 1973, 1974 and Lewis 1974 also defend the view that what it is to have a propositional attitude is just to be interpretable in a particular way. It is, however, not entirely clear whether they intend their views to imply irrealism about propositional attitudes.). Stich (1983) argues that cognitive psychology does not (or, in any case, should not) taxonomize mental states by their semantic properties at all, since attribution of psychological states by content is sensitive to factors that render it problematic in the context of a scientific psychology. Cognitive psychology seeks causal explanations of behaviour and cognition, and the causal powers of a mental state are determined by its intrinsic ‘structural’ or ‘syntactic’ properties. The semantic properties of a mental state, however, are determined by its extrinsic properties-e.g., its history, environmental or intra-mental relations. Hence, such properties cannot figure in causal-scientific explanations of behaviour. (Fodor 1994 and Dretske 1988 are realist attempts to come to grips with some of these problems.) Stich proposes a syntactic theory of the mind, on which the semantic properties of mental states play no explanatory role.
 It is a traditional assumption among realists about mental representations that representational states come in two basic varieties (Boghossian 1995). There are those, such as thoughts, which are composed of concepts and have no phenomenal (‘what-it's-like’) features (‘qualia’), and those, such as sensory experiences, which have phenomenal features but no conceptual constituents. (Non-conceptual content is usually defined as a kind of content that states of a creature lacking concepts might nonetheless enjoy. On this taxonomy, mental states can represent either in a way analogous to expressions of natural languages or in a way analogous to drawings, paintings, maps or photographs. (Perceptual states such as seeing that something is blue, are sometimes thought of as hybrid states, consisting of, for example, a Non-conceptual sensory experience and a thought, or some more integrated compound of sensory and conceptual components.)
 Some historical discussions of the representational properties of mind (e.g., Aristotle 1984, Locke 1689/1975, Hume 1739/1978) seem to assume that Non-conceptual representations-percepts (‘impressions’), images (‘ideas’) and the like-are the only kinds of mental representations, and that the mind represents the world in virtue of being in states that resemble things in it. On such a view, all representational states have their content in virtue of their phenomenal features. Powerful arguments, however, focussing on the lack of generality (Berkeley 1975), ambiguity (Wittgenstein 1953) and non-compositionality (Fodor 1981) of sensory and imagistic representations, as well as their unsuitability to function as logical (Frége 1918/1997, Geach 1957) or mathematical (Frége 1884/1953) concepts, and the symmetry of resemblance (Goodman 1976), convinced philosophers that no theory of mind can get by with only Non-conceptual representations construed in this way.
 Contemporary disagreement over Non-conceptual representation concerns the existence and nature of phenomenal properties and the role they play in determining the content of sensory experience. Dennett (1988), for example, denies that there are such things as qualia at all; while Brandom (2002), McDowell (1994), Rey (1991) and Sellars (1956) deny that they are needed to explain the content of sensory experience. Among those who accept that experiences have phenomenal content, some (Dretske, Lycan, Tye) argue that it is reducible to a kind of intentional content, while others (Block, Loar, Peacocke) argue that it is irreducible.
 There has also been dissent from the traditional claim that conceptual representations (thoughts, beliefs) lack phenomenology. Chalmers (1996), Flanagan (1992), Goldman (1993), Horgan and Tiensen (2003), Jackendoff (1987), Levine (1993, 1995, 2001), McGinn (1991), Pitt (2004), Searle (1992), Siewert (1998) and Strawson (1994), claim that purely symbolic (conscious) representational states themselves have a (perhaps proprietary) phenomenology. If this claim is correct, the question of what role phenomenology plays in the determination of content reprises for conceptual representation; and the eliminativist ambitions of Sellars, Brandom, Rey, would meet a new obstacle. (It would also raise prima face problems for reductionist representationalism
 The representationalist thesis is often formulated as the claim that phenomenal properties are representational or intentional. However, this formulation is ambiguous between a reductive and a non-deductive claim (though the term ‘representationalism’ is most often used for the reductive claim). On one hand, it could mean that the phenomenal content of an experience is a kind of intentional content (the properties it represents). On the other, it could mean that the (irreducible) phenomenal properties of an experience determine an intentional content. Representationalists such as Dretske, Lycan and Tye would assent to the former claim, whereas phenomenalists such as Block, Chalmers, Loar and Peacocke would assent to the latter. (Among phenomenalists, there is further disagreement about whether qualia are intrinsically representational (Loar) or not (Block, Peacocke).
 Most (reductive) representationalists are motivated by the conviction that one or another naturalistic explanation of intentionality is, in broad outline, correct, and by the desire to complete the naturalization of the mental by applying such theories to the problem of phenomenality. (Needless to say, most phenomenalists (Chalmers is the major exception) are just as eager to naturalize the phenomenal-though not in the same way.)
 The main argument for representationalism appeals to the transparency of experience (cf. Tye 2000: 45-51). The properties that characterize what it's like to have a perceptual experience are presented in experience as properties of objects perceived: in attending to an experience, one seems to ‘see through it’ to the objects and properties it is experiences of. They are not presented as properties of the experience itself. If nonetheless they were properties of the experience, perception would be massively deceptive. But perception is not massively deceptive. According to the representationalist, the phenomenal character of an experience is due to its representing objective, non-experiential properties. (In veridical perception, these properties are locally instantiated; in illusion and hallucination, they are not.) On this view, introspection is indirect perception: one comes to know what phenomenal features one's experience has by coming to know what objective features it represents.
 In order to account for the intuitive differences between conceptual and sensory representations, representationalists appeal to their structural or functional differences. Dretske (1995), for example, distinguishes experiences and thoughts on the basis of the origin and nature of their functions: an experience of a property 'P' is a state of a system whose evolved function is to indicate the presence of 'P' in the environment; a thought representing the property 'P', on the other hand, is a state of a system whose assigned (learned) function is to calibrate the output of the experiential system. Rey (1991) takes both thoughts and experiences to be relations to sentences in the language of thought, and distinguishes them on the basis of (the functional roles of) such sentences' constituent predicates. Lycan (1987, 1996) distinguishes them in terms of their functional-computational profiles. Tye (2000) distinguishes them in terms of their functional roles and the intrinsic structure of their vehicles: thoughts are representations in a language-like medium, whereas experiences are image-like representations consisting of ‘symbol-filled arrays.’ (the account of mental images in Tye 1991.)
 Phenomenalists tend to make use of the same sorts of features (function, intrinsic structure) in explaining some of the intuitive differences between thoughts and experiences; but they do not suppose that such features exhaust the differences between phenomenal and non-phenomenal representations. For the phenomenalism, it is the phenomenal properties of experiences-qualia themselves-that constitute the fundamental difference between experience and thought. Peacocke (1992), for example, develops the notion of a perceptual ‘scenario’ (an assignment of phenomenal properties to coordinates of a three-dimensional egocentric space), whose content is ‘correct’ (a semantic property) if in the corresponding ‘scene’ (the portion of the external world represented by the scenario) properties are distributed as their phenomenal analogues are in the scenario.
 Another sort of representation championed by phenomenalists (e.g., Block, Chalmers (2003) and Loar (1996)) is the ‘phenomenal concept’-a conceptual/phenomenal hybrid consisting of a phenomenological ‘sample’ (an image or an occurrent sensation) integrated with (or functioning as) a conceptual component. Phenomenal concepts are postulated to account for the apparent fact (among others) that, as McGinn (1991) puts it, ‘you cannot form [introspective] concepts of conscious properties unless you yourself instantiate those properties.’ One cannot have a phenomenal concept of a phenomenal property 'P', and, hence, phenomenal beliefs about P, without having experience of 'P', because 'P' itself is (in some way) constitutive of the concept of 'P'. (Jackson 1982, 1986 and Nagel 1974.)
 Though imagery has played an important role in the history of philosophy of mind, the important contemporary literature on it is primarily psychological. In a series of psychological experiments done in the 1970s (summarized in Kosslyn 1980 and Shepard and Cooper 1982), subjects' response time in tasks involving mental manipulation and examination of presented figures was found to vary in proportion to the spatial properties (size, orientation, etc.) of the figures presented. The question of how these experimental results are to be explained has kindled a lively debate on the nature of imagery and imagination.
 Kosslyn (1980) claims that the results suggest that the tasks were accomplished via the examination and manipulation of mental representations that themselves have spatial properties-i.e., pictorial representations, or images. Others, principally Pylyshyn (1979, 1981, 2003), argue that the empirical facts can be explained in terms exclusively of discursive, or propositional representations and cognitive processes defined over them. (Pylyshyn takes such representations to be sentences in a language of thought.)
 The idea that pictorial representations are literally pictures in the head is not taken seriously by proponents of the pictorial view of imagery The claim is, rather, that mental images represent in a way that is relevantly like the way pictures represent. (Attention has been focussed on visual imagery-hence the designation ‘pictorial’; though of course there may imagery in other modalities-auditory, olfactory, etc.-as well.)
 The distinction between pictorial and discursive representation can be characterized in terms of the distinction between analog and digital representation (Goodman 1976). This distinction has itself been variously understood (Fodor & Pylyshyn 1981, Goodman 1976, Haugeland 1981, Lewis 1971, McGinn 1989), though a widely accepted construal is that analog representation is continuous (i.e., in virtue of continuously variable properties of the representation), while digital representation is discrete (i.e., in virtue of properties a representation either has or doesn't have) (Dretske 1981). (An analog/digital distinction may also be made with respect to cognitive processes. (Block 1983.)) On this understanding of the analog/digital distinction, imagistic representations, which represent in virtue of properties that may vary continuously (such as being more or less bright, loud, vivid, etc.), would be analog, while conceptual representations, whose properties do not vary continuously (a thought cannot be more or less about Elvis: either it is or it is not) would be digital.
 It might be supposed that the pictorial/discursive distinction is best made in terms of the phenomenal and nonphenomenal distinction, but it is not obvious that this is the case. For one thing, there may be nonphenomenal properties of representations that vary continuously. Moreover, there are ways of understanding pictorial representation that presuppose neither phenomenality nor analogicity. According to Kosslyn (1980, 1982, 1983), a mental representation is ‘quasi-pictorial’ when every part of the representation corresponds to a part of the object represented, and relative distances between parts of the object represented are preserved among the parts of the representation. But distances between parts of a representation can be defined functionally rather than spatially-for example, in terms of the number of discrete computational steps required to combine stored information about them. (Rey 1981.)
 Tye (1991) proposes a view of images on which they are hybrid representations, consisting both of pictorial and discursive elements. On Tye's account, images are ‘(labelled) interpreted symbol-filled arrays.’ The symbols represent discursively, while their arrangement in arrays has representational significance (the location of each ‘cell’ in the array represents a specific viewer-centred 2-D location on the surface of the imagined object)
 The contents of mental representations are typically taken to be abstract objects (properties, relations, propositions, sets, etc.). A pressing question, especially for the naturalist, is how mental representations come to have their contents. Here the issue is not how to naturalize content (abstract objects can't be naturalized), but, rather, how to provide a naturalistic account of the content-determining relations between mental representations and the abstract objects they express. There are two basic types of contemporary naturalistic theories of content-determination, causal-informational and functional.
 Causal-informational theories (Dretske 1981, 1988, 1995) hold that the content of a mental representation is grounded in the information it carries about what does (Devitt 1996) or would (Fodor 1987, 1990) cause it to occur. There is, however, widespread agreement that causal-informational relations are not sufficient to determine the content of mental representations. Such relations are common, but representation is not. Tree trunks, smoke, thermostats and ringing telephones carry information about what they are causally related to, but they do not represent (in the relevant sense) what they carry information about. Further, a representation can be caused by something it does not represent, and can represent something that has not caused it.
 The main attempts to specify what makes a causal-informational state a mental representation are Asymmetric Dependency Theories (e.g., Fodor 1987, 1990, 1994) and Teleological Theories (Fodor 1990, Millikan 1984, Papineau 1987, Dretske 1988, 1995). The Asymmetric Dependency Theory distinguishes merely informational relations from representational relations on the basis of their higher-order relations to each other: informational relations depend upon representational relations, but not vice-versa. For example, if tokens of a mental state type are reliably caused by horses, cows-on-dark-nights, zebras-in-the-mist and Great Danes, then they carry information about horses, etc. If, however, such tokens are caused by cows-on-dark-nights, etc. because they were caused by horses, but not vice versa, then they represent horses.
 According to Teleological Theories, representational relations are those a representation-producing mechanism has the selected (by evolution or learning) function of establishing. For example, zebra-caused horse-representations do not mean zebra, because the mechanism by which such tokens are produced has the selected function of indicating horses, not zebras. The horse-representation-producing mechanism that responds to zebras is malfunctioning.
 Functional theories (Block 1986, Harman 1973), hold that the content of a mental representation is grounded in its (causal computational, inferential) relations to other mental representations. They differ on whether relata should include all other mental representations or only some of them, and on whether to include external states of affairs. The view that the content of a mental representation is determined by its inferential/computational relations with all other representations is holism; the view it is determined by relations to only some other mental states is localism (or molecularism). (The view that the content of a mental state depends on none of its relations to other mental states is atomism.) Functional theories that recognize no content-determining external relata have been called solipsistic (Harman 1987). Some theorists posit distinct roles for internal and external connections, the former determining semantic properties analogous to sense, the latter determining semantic properties analogous to reference (McGinn 1982, Sterelny 1989)
 (Reductive) representationalists (Dretske, Lycan, Tye) usually take one or another of these theories to provide an explanation of the (Non-conceptual) content of experiential states. They thus tend to be Externalists about phenomenological as well as conceptual content. Phenomenalists and non-deductive representationalists (Block, Chalmers, Loar, Peacocke, Siewert), on the other hand, take it that the representational content of such states is (at least in part) determined by their intrinsic phenomenal properties. Further, those who advocate a phenomenology-based approach to conceptual content (Horgan and Tiensen, Loar, Pitt, Searle, Siewert) also seem to be committed to internalist individuation of the content (if not the reference) of such states.
 Generally, those who, like informational theorists, think relations to one's (natural or social) environment are (at least partially) determinative of the content of mental representations are Externalists (e.g., Burge 1979, 1986, McGinn 1977, Putnam 1975), whereas those who, like some proponents of functional theories, think representational content is determined by an individual's intrinsic properties alone, are internalists (or individualists; cf. Putnam 1975, Fodor 1981)
 This issue is widely taken to be of central importance, since psychological explanation, whether commonsense or scientific, is supposed to be both causal and content-based. (Beliefs and desires cause the behaviours they do because they have the contents they do. For example, the desire that one have a beer and the beliefs that there is beer in the refrigerator and that the refrigerator is in the kitchen may explain one's getting up and going to the kitchen.) If, however, a mental representation's having a particular content is due to factors extrinsic to it, it is unclear how its having that content could determine its causal powers, which, arguably, must be intrinsic. Some who accept the standard arguments for externalism have argued that internal factors determine a component of the content of a mental representation. They say that mental representations have both ‘narrow’ content (determined by intrinsic factors) and ‘wide’ or ‘broad’ content (determined by narrow content plus extrinsic factors). (This distinction may be applied to the sub-personal representations of cognitive science as well as to those of commonsense psychology.
 Narrow content has been variously construed. Putnam (1975), Fodor (1982)), and Block (1986), for example, seem to understand it as something like dedicto content (i.e., Frégean sense, or perhaps character, à la Kaplan 1989). On this construal, narrow content is context-independent and directly expressible. Fodor (1987) and Block (1986), however, have also characterized narrow content as radically inexpressible. On this construal, narrow content is a kind of proto-content, or content-determinant, and can be specified only indirectly, via specifications of context/wide-content pairings. On both construal, narrow contents are characterized as functions from context to (wide) content. The narrow content of a representation is determined by properties intrinsic to it or its possessor such as its syntactic structure or its intra-mental computational or inferential role (or its phenomenology).
 Burge (1986) has argued that causation-based worries about externalist individuation of psychological content, and the introduction of the narrow notion, are misguided. Fodor (1994, 1998) has more recently urged that a scientific psychology might not need narrow content in order to supply naturalistic (causal) explanations of human cognition and action, since the sorts of cases they were introduced to handle, viz., Twin-Earth cases and Frigg cases, are either nomologically impossible or dismissible as exceptions to non-strict psychological laws.
 The leading contemporary version of the Representational Theory of Mind, the Computational Theory of Mind (CTM), claims that the brain is a kind of computer and that mental processes are computations. According to the computational theory of mind, cognitive states are constituted by computational relations to mental representations of various kinds, and cognitive processes are sequences of such states. The computational theory of mind and the representational theory of mind, may by attempting to explain all psychological states and processes in terms of mental representation. In the course of constructing detailed empirical theories of human and animal cognition and developing models of cognitive processes implementable in artificial information processing systems, cognitive scientists have proposed a variety of types of mental representations. While some of these may be suited to be mental relata of commonsense psychological states, some-so-called ‘subpersonal’ or ‘sub-doxastic’ representations-are not. Though many philosophers believe that computational theory of mind can provide the best scientific explanations of cognition and behaviour, there is disagreement over whether such explanations will vindicate the commonsense psychological explanations of prescientific representational theory of mind.
 According to Stich's (1983) Syntactic Theory of Mind, for example, computational theories of psychological states should concern themselves only with the formal properties of the objects those states are relations to. Commitment to the explanatory relevance of content, however, is for most cognitive scientists fundamental (Fodor 1981, Pylyshyn 1984, Von Eckardt 1993). That mental processes are computations, which computations are rule-governed sequences of semantically evaluable objects, and that the rules apply to the symbols in virtue of their content, are central tenets of mainstream cognitive science.
 Explanations in cognitive science appeal to a many different kinds of mental representation, including, for example, the ‘mental models’ of Johnson-Laird 1983, the ‘retinal arrays,’ ‘primal sketches’ and ‘2½ -D sketches’ of Marr 1982, the ‘frames’ of Minsky 1974, the ‘sub-symbolic’ structures of Smolensky 1989, the ‘quasi-pictures’of Kosslyn 1980, and the ‘interpreted symbol-filled arrays’ of Tye 1991-in addition to representations that may be appropriate to the explanation of commonsense psychological states. Computational explanations have been offered of, among other mental phenomena, belief (Fodor 1975, Field 1978), visual perception (Marr 1982, Osherson, et al. 1990), rationality (Newell and Simon 1972, Fodor 1975, Johnson-Laird and Wason 1977), language learning and  (Chomsky 1965, Pinker 1989), and musical comprehension (Lerdahl and Jackendoff 1983).
 A fundamental disagreement among proponents of computational theory of mind concerns the realization of personal-level representations (e.g., thoughts) and processes (e.g., inferences) in the brain. The central debate here is between proponents of Classical Architectures and proponents of Conceptionist Architectures.
 The classicists (e.g., Turing 1950, Fodor 1975, Fodor and Pylyshyn 1988, Marr 1982, Newell and Simon 1976) hold that mental representations are symbolic structures, which typically have semantically evaluable constituents, and that mental processes are rule-governed manipulations of them that are sensitive to their constituent structure. The connectionists (e.g., McCulloch & Pitts 1943, Rumelhart 1989, Rumelhart and McClelland 1986, Smolensky 1988) hold that mental representations are realized by patterns of activation in a network of simple processors (‘nodes’) and that mental processes consist of the spreading activation of such patterns. The nodes themselves are, typically, not taken to be semantically evaluable; nor do the patterns have semantically evaluable constituents. (Though there are versions of Connectionism-‘localist’ versions-on which individual nodes are taken to have semantic properties (e.g., Ballard 1986, Ballard & Hayes 1984).) It is arguable, however, that localist theories are neither definitive nor representative of the Conceptionist program (Smolensky 1988, 1991, Chalmers 1993).
 Classicists are motivated (in part) by properties thought seems to share with language. Fodor's Language of Thought Hypothesis (LOTH) (Fodor 1975, 1987), according to which the system of mental symbols constituting the neural basis of thought is structured like a language, provides a well-worked-out version of the classical approach as applied to commonsense psychology. According to the language of thought hypothesis, the potential infinity of complex representational mental states is generated from a finite stock of primitive representational states, in accordance with recursive formation rules. This combinatorial structure accounts for the properties of productivity and systematicity of the system of mental representations. As in the case of symbolic languages, including natural languages (though Fodor does not suppose either that the language of thought hypothesis explains only linguistic capacities or that only verbal creatures have this sort of cognitive architecture), these properties of thought are explained by appeal to the content of the representational units and their combinability into contentful complexes. That is, the semantics of both language and thought is compositional: the content of a complex representation is determined by the contents of its constituents and their structural configuration.
 Connectionists are motivated mainly by a consideration of the architecture of the brain, which apparently consists of layered networks of interconnected neurons. They argue that this sort of architecture is unsuited to carrying out classical serial computations. For one thing, processing in the brain is typically massively parallel. In addition, the elements whose manipulation drives computation in Conceptionist networks (principally, the connections between nodes) are neither semantically compositional nor semantically evaluable, as they are on the classical approach. This contrast with classical computationalism is often characterized by saying that representation is, with respect to computation, distributed as opposed to local: representation is local if it is computationally basic; and distributed if it is not. (Another way of putting this is to say that for classicists mental representations are computationally atomic, whereas for connectionists they are not.)
 Moreover, connectionists argue that information processing as it occurs in Conceptionist networks more closely resembles some features of actual human cognitive functioning. For example, whereas on the classical view learning involves something like hypothesis formation and testing (Fodor 1981), on the Conceptionist model it is a matter of evolving distribution of ‘weight’ (strength) on the connections between nodes, and typically does not involve the formulation of hypotheses regarding the identity conditions for the objects of knowledge. The Conceptionist network is ‘trained up’ by repeated exposure to the objects it is to learn to distinguish; and, though networks typically require many more exposures to the objects than do humans, this seems to model at least one feature of this type of human learning quite well.
 Further, degradation in the performance of such networks in response to damage is gradual, not sudden as in the case of a classical information processor, and hence more accurately models the loss of human cognitive function as it typically occurs in response to brain damage. It is also sometimes claimed that Conceptionist systems show the kind of flexibility in response to novel situations typical of human cognition-situations in which classical systems are relatively ‘brittle’ or ‘fragile.’
 Some philosophers have maintained that Connectionism entails that there are no propositional attitudes. Ramsey, Stich and Garon (1990) have argued that if Conceptionist models of cognition are basically correct, then there are no discrete representational states as conceived in ordinary commonsense psychology and classical cognitive science. Others, however (e.g., Smolensky 1989), hold that certain types of higher-level patterns of activity in a neural network may be roughly identified with the representational states of commonsense psychology. Still others (e.g., Fodor & Pylyshyn 1988, Heil 1991, Horgan and Tienson 1996) argue that language-of-thought style representation is both necessary in general and realizable within Conceptionist architectures. (MacDonald & MacDonald 1995 collects the central contemporary papers in the classicist/Conceptionist debate, and provides useful introductory material as well.
 Whereas Stich (1983) accepts that mental processes are computational, but denies that computations are sequences of mental representations, others accept the notion of mental representation, but deny that computational theory of mind provides the correct account of mental states and processes.
 Van Gelder (1995) denies that psychological processes are computational. He argues that cognitive systems are dynamic, and that cognitive states are not relations to mental symbols, but quantifiable states of a complex system consisting of (in the case of human beings) a nervous system, a body and the environment in which they are embedded. Cognitive processes are not rule-governed sequences of discrete symbolic states, but continuous, evolving total states of dynamic systems determined by continuous, simultaneous and mutually determining states of the systems' components. Representation in a dynamic system is essentially information-theoretic, though the bearers of information are not symbols, but state variables or parameters.
 Horst (1996), on the other hand, argues that though computational models may be useful in scientific psychology, they are of no help in achieving a philosophical understanding of the intentionality of commonsense mental states. computational theory of mind attempts to reduce the intentionality of such states to the intentionality of the mental symbols they are relations to. But, Horst claims, the relevant notion of symbolic content is essentially bound up with the notions of convention and intention. So the computational theory of mind involves itself in a vicious circularity: the very properties that are supposed to be reduced are (tacitly) appealed to in the reduction.
 To say that a mental object has semantic properties is, paradigmatically, to say that it may be about, or be true or false of, an object or objects, or that it may be true or false simpliciter. Suppose I think that ocelots take snuff. I am thinking about ocelots, and if what I think of them (that they take snuff) is true of them, then my thought is true. According to representational theory of mind such states are to be explained as relations between agents and mental representations. To think that ocelots take snuff is to token in some way a mental representation whose content is that ocelots take snuff. On this view, the semantic properties of mental states are the semantic properties of the representations they are relations to.
 Linguistic acts seem to share such properties with mental states. Suppose I say that ocelots take snuff. I am talking about ocelots, and if what I say of them (that they take snuff) is true of them, then my utterance is true. Now, to say that ocelots take snuff is (in part) to utter a sentence that means that ocelots take snuff. Many philosophers have thought that the semantic properties of linguistic expressions are inherited from the intentional mental states they are conventionally used to express (Grice 1957, Fodor 1978, Schiffer, 1972/1988, Searle 1983). On this view, the semantic properties of linguistic expressions are the semantic properties of the representations that are the mental relata of the states they are conventionally used to express.
 It is also widely held that in addition to having such properties as reference, truth-conditions and truth-so-called extensional properties-expressions of natural languages also have intensional properties, in virtue of expressing properties or propositions-i.e., in virtue of having meanings or senses, where two expressions may have the same reference, truth-conditions or truth value, yet express different properties or propositions (Frigg 1892/1997). If the semantic properties of natural-language expressions are inherited from the thoughts and concepts they express (or vice versa, or both), then an analogous distinction may be appropriate for mental representations.
 Søren Aabye Kierkegaard (1813-1855), a Danish religious philosopher, whose concern with individual existence, choice, and commitment profoundly influenced modern theology and philosophy, especially existentialism.
 Søren Kierkegaard wrote of the paradoxes of Christianity and the faith required to reconcile them. In his book Fear and Trembling, Kierkegaard discusses Genesis 22, in which God commands Abraham to kill his only son, Isaac. Although God made an unreasonable and immoral demand, Abraham obeyed without trying to understand or justify it. Kierkegaard regards this ‘leap of faith’ as the essence of Christianity.
 Kierkegaard was born in Copenhagen on May 15, 1813. His father was a wealthy merchant and strict Lutheran, whose gloomy, guilt-ridden piety and vivid imagination strongly influenced Kierkegaard. Kierkegaard studied theology and philosophy at the University of Copenhagen, where he encountered Hegelian philosophy and reacted strongly against it. While at the university, he ceased to practice Lutheranism and for a time led an extravagant social life, becoming a familiar figure in the theatrical and café society of Copenhagen. After his father's death in 1838, however, he decided to resume his theological studies. In 1840 he became engaged to the 17-year-old Regine Olson, but almost immediately he began to suspect that marriage was incompatible with his own brooding, complicated nature and his growing sense of a philosophical vocation. He abruptly broke off the engagement in 1841, but the episode took on great significance for him, and he repeatedly alluded to it in his books. At the same time, he realized that he did not want to become a Lutheran pastor. An inheritance from his father allowed him to devote himself entirely to writing, and in the remaining 14 years of his life he produced more than 20 books.
 What some person expresses of a sentence often depends on the environment in which he or she is placed. For example, the disease I refer to by a term like arthritis or the kind of tree I call of its criteria will define a beech of which I know next to nothing. This raises the possibility of imaging two persons as an alternative different environment, but in which everything appears the same to each of them. The wide content of their thoughts and saying will be different if the situation surrounding them is appropriately different, situation may reorientate the inclusions that the actual objects hey perceive, or the chemical or physical kinds of objects in the world they inhabit, or the history of their words, or the decisions of authorities on what counts as an example of one term thy use. The narrow content is that part of their thought that remains identical, through the identity of the way things appear, despite these differences of surroundings. Partisans of wide . . . as, something called broadly, content may doubt whether any content is in this sense narrow, partisans of narrow content believe that it is the fundamental notion, with wide content being on narrow content confirming context.
 All and all, assuming their rationality has characterized people is common, and the most evident display of our rationality is capable to think. This is the rehearsal in the mind of what to say, or what to do. Not all thinking is verbal, since chess players, composers, and painters all think, and there is no deductive reason that their deliberations should take any more verbal a form than their actions. It is permanently tempting to conceive of this activity about the presence in the mind of elements of some language, or other medium that represents aspects of the world and its surrounding surface structures. However, the model has been attacked, notably by Ludwig Wittgenstein (1889-1951), whose influential application of these ideas was in the philosophy of mind. Wittgenstein explores the role that reports of introspection, or sensations, or intentions, or beliefs can play of our social lives, to undermine the Cartesian mental picture is that they functionally describe the goings-on in an inner theatre of which the subject is the lone spectator. Passages that have sub sequentially become known as the rule following considerations and the private language argument are among the fundamental topics of modern philosophy of language and mind, although their precise interpretation is endlessly controversial.
 Effectively, the hypotheses especially associated with Jerry Fodor (1935- ), whom is known for the resolute realism; Virtually, the substances initially involved and known by nature’s psychological or mental functions occurring in or of a language different from one’s commonly acquainted by rule. It is important to know that the foreign boundaries of constraints and sternful rigidity have confirmed that beyond our in-born ingressions are those collected by and afar and above, find in commonality that they do things differently there. Yet the customary or common type encountered in the normal course of events, findings to its commonplace of ordinary language, but underlying and explaining our competence with it. The idea is a development of the notion of an innate universal grammar (Avram Noam Chomsky, 1928-), in as such, that we agree that since a computer programs are linguistically complex sets of instructions were the relative  executions by which explains of surface behavior or the adequacy of the computerized programming installations, if it were definably amendable and, advisably corrective, in that most are disconcerting of many that are ultimately a reason for us of thinking intuitively and without the indulgence of retrospective preferences, but an ethical majority in defending of its moral line that is already confronting us. That these programs may or may not improve to conditions that are lastly to enhance of the right sort of an existence forwarded toward a more valuing amount in humanities lesser extensions that embrace ones riff of necessity to humanities abeyance to expressions in the finer of qualities.
 As an explanation of ordinary language-learning and competence, the hypothesis has not found universal favours, as only ordinary representational powers that by invoking the image of the learning persons capabilities are apparently whom the abilities for translating are contending of an innate language whose own powers are mysteriously a biological given. Perhaps, the view that everyday attributions of intentionality, beliefs, and meaning to other persons proceed by means of a tactic use of a theory that enables one to construct these interpretations as explanations of their doings. We commonly hold the view along with functionalism, according to which psychological states are theoretical entities, identified by the network of their causes and effects. The theory-theory has different implications, depending upon which feature of theories we are stressing. Theories may be thought of as capable of formalization, as yielding predictions and explanations, as achieved by a process of theorizing, as answering to empirical evidence that is in principle describable without them, as liable to be overturned by newer and better theories, and so on.
 The main problem with seeing our understanding of others as the outcome of a piece of theorizing is the nonexistence of a medium in which this theory can be couched, as the child learns simultaneously the minds of others and the meaning of terms in its native language, is not gained by the tactic use of a theory, enabling us to infer what thoughts or intentions explain their actions, but by re-living the situation in their shoes or from their point of view, and by that understanding what they experienced and theory, and therefore expressed. Understanding others is achieved when we can ourselves deliberate as they did, and hear their words as if they are our own. The suggestion is a modern development frequently associated in the Verstehen traditions of Dilthey (1833-1911), Weber (1864-1920) and Collingwood (1889-1943).
 We may call any process of drawing a conclusion from a set of premises a process of reasoning. If the conclusion concerns what to do, the process is called practical reasoning, otherwise pure or theoretical reasoning. Evidently, such processes may be good or bad, if they are good, the premises support or even entail the conclusion drawn, and if they are bad, the premises offer no support to the conclusion. Formal logic studies the cases in which conclusions are validly drawn from premises, but little human reasoning is overly of the forms logicians identify. Partly, we are concerned to draw conclusions that go beyond our premises, in the way that conclusions of logically valid arguments do not for the process of using evidence to reach a wider conclusion. Nonetheless, such anticipatory pessimism in the opposite direction to the prospects of conformation theory, denying that we can assess the results of abduction in terms of probability. A cognitive process of reasoning in which a conclusion is played-out from a set of premises usually confined of cases in which the conclusions are supposed in following from the premises, i.e., an inference is logically valid, in that of deductibility in a logically defined syntactic premise but without there being to any reference to the intended interpretation of its theory. Furthermore, as we reason we use indefinite traditional knowledge or commonsense sets of presuppositions about what it is likely or not a task of an automated reasoning project, which is to mimic this causal use of knowledge of the way of the world in computer programs.
 Some theories usually emerge themselves of engaging to exceptionally explicit predominance as [supposed] truth that they have not organized, making the theory difficult to survey or study as a whole. The axiomatic method is an idea for organizing a theory, one in which tries to select from among the supposed truths a small number from which they can see all others to be deductively inferable. This makes the theory more tractable since, in a sense, they contain all truth in those few. In a theory so organized, they call the few truth from which they deductively imply all others axioms. David Hilbert (1862-1943) had argued that, just as algebraic and differential equations, which we were used to study mathematical and physical processes, could have themselves be made mathematical objects, so axiomatic theories, like algebraic and differential equations, which are means to representing physical processes and mathematical structures could be of investigating.
 Conformation to theory, the philosophy of science, is a generalization or set referring to unobservable entities, i.e., atoms, genes, quarks, unconscious wishes. The ideal gas law, for example, refers to such observable pressures, temperature, and volume, the molecular-kinetic theory refers to molecules and their material possession, . . . although an older usage suggests the lack of adequate evidence in support thereof, as an existing philosophical usage does in truth, follow in the tradition (as in Leibniz, 1704), as many philosophers had the conviction that all truth, or all truth about a particular domain, followed from as few than for being many governing principles. These principles were taken to be either metaphysically prior or epistemologically prior or both. In the first sense, they we took to be entities of such a nature that what exists s caused by them. When the principles were taken as epistemologically prior, that is, as axioms, they were taken to be privileged epistemologically, e.g., self-evident, which is not needed for demonstration, or again, included or, to such that all truth so truly follows from them by deductive inferences. Gödel (1984) showed in the spirit of Hilbert, treating axiomatic theories as themselves mathematical objects that mathematics, and even a small part of mathematics, elementary number theory, could not be axiomatized, that more precisely, any class of axioms that is such that we could effectively decide, of any proposition, whether or not it was in that class, would be too small to capture in of the truth.
 The notion of truth occurs with remarkable frequency in our reflections on language, thought and action. We are inclined to suppose, for example, that truth is the proper aim of scientific inquiry, that true beliefs help to achieve our goals, that to understand a sentence is to know which circumstances would make it true, that reliable preservation of truth as one argues of valid reasoning, that moral pronouncements should not be regarded as objectively true, and so on. To assess the plausibility of such theses, and to refine them and to explain why they hold (if they do), we require some view of what truth be a theory that would account for its properties and its relations to other matters. Thus, there can be little prospect of understanding our most important faculties in the sentence of a good theory of truth.
 Such a thing, however, has been notoriously elusive. The ancient idea that truth is some sort of correspondence with reality has still never been articulated satisfactorily, and the nature of the alleged correspondence and the alleged reality persistently remains objectionably enigmatical. Yet the familiar alternative suggestions that true beliefs are those that are mutually coherent, or pragmatically useful, or verifiable in suitable conditions has each been confronted with persuasive counterexamples. A twentieth-century departure from these traditional analyses is the view that truth is not a property at all that the syntactic form of the predicate, is true, distorts its really semantic character, which is not to describe propositions but to endorse them. Nevertheless, we have also faced this radical approach with difficulties and suggest, counter intuitively that truth cannot have the vital theoretical role in semantics, epistemology and elsewhere that we are naturally inclined to give it. Thus, truth threatens to remain one of the most enigmatic of notions: An explicit account of it can seem essential yet beyond our reach. All the same, recent work provides some evidence for optimism.
 A theory is based in philosophy of science, is a generalization or se of generalizations purportedly referring to observable entities, i.e., atoms, quarks, unconscious wishes, and so on. The ideal gas law, for example, cites to only such observable pressures, temperature, and volume, the molecular-kinetic theory refers top molecules and their properties, although an older usage suggests the lack of an adequate make out in support wherefrom as merely a theory, latter-day philosophical usage does not carry that connotation. Einstein's special and General Theory of Relativity, for example, is taken to be extremely well founded.
 These are two main views on the nature of theories. According to the received view theories are partially interpreted axiomatic systems, according to the semantic view; a theory is a collection of models (Suppe, 1974). By which, some possibilities, unremarkably emerge as supposed truth that no one has neatly systematized by making theory difficult to make a survey of or study as a whole. The axiomatic method is an ideal for organizing a theory (Hilbert, 1970), one tries to select from among the supposed truths a small number from which they can see all the others to be deductively inferable. This makes the theory more tractable since, in a sense, they contain all truth in those few. In a theory so organized, they call the few truth from which they deductively incriminate all others axioms. David Hilbert (1862-1943) had argued that, morally justified as algebraic and differential equations, which were antiquated into the study of mathematical and physical processes, could hold on to themselves and be made mathematical objects, so they could make axiomatic theories, like algebraic and differential equations, which are means of representing physical processes and mathematical structures, objects of mathematical investigation.
 In the tradition (as in Leibniz, 1704), many philosophers had the conviction that all truth, or all truth about a particular domain, followed from a few principles. These principles were taken to be metaphysically prior or epistemologically prior or both. In the first sense, they were taken to be entities of such a nature that what exists is caused by them. When the principles were taken as epistemological prior, that is, as axioms, they were taken to be privileged epistemology, i.e., self-evident, not needing to be demonstrated, or again, inclusive or, to be such that all truth do in truth follow from them (by deductive inferences). Gödel (1984) showed in the spirit of Hilbert, treating axiomatic theories as themselves mathematical objects that mathematics, and even a small part. Of mathematics, elementary number theory, could not be axiomatized, that, more precisely, any class of axioms that is such that we could effectively decide, of any proposition, whether or not it was in that class, would be too small to capture all of the truth.
 The notion of truth occurs with remarkable frequency in our reflections on language, thought, and action. We are inclined to suppose, for example, that truth is the proper aim of scientific inquiry, that true beliefs help us to achieve our goals, tat to understand a sentence is to know which circumstances would make it true, that reliable preservation of truth as one argues from premises to a conclusion is the mark of valid reasoning, that moral pronouncements should not be regarded as objectively true, and so on. In order to assess the plausible of such theses, and in order to refine them and to explain why they hold, if they do, we expect some view of what truth be of a theory that would keep an account of its properties and its relations to other matters. Thus, there can be little prospect of understanding our most important faculties without a good theory of truth.
 The ancient idea that truth is one sort of correspondence with reality has still never been articulated satisfactorily: The nature of the alleged correspondence and the alleged reality remains objectivably rid of obstructions. Yet, the familiar alternative suggests ~. That true beliefs are those that are mutually coherent, or pragmatically useful, or verifiable in suitable conditions has each been confronted with persuasive counterexamples. A twentieth-century departure from these traditional analyses is the view that truth is not a property at al ~. That the syntactic form of the predicate . . . is true, distorts the real semantic character, with which is not to describe propositions but to endorse them. Still, this radical approach is also faced with difficulties and suggests, counter intuitively that truth cannot have the vital theoretical role in semantics, epistemology and elsewhere that we are naturally inclined to give it. Thus, truth threatens to remain one of the most enigmatic of notions, and a confirming account of it can seem essential yet, on the far side of our reach. However, recent work provides some grounds for optimism.
 The belief that snow is white owes its truth to a certain feature of the external world, namely, to the fact that snow is white. Similarly, the belief that dogs bark is true because of the fact that dogs bark. This trivial observation leads to what is perhaps the most natural and popular account of truth, the correspondence theory, according to which a belief (statement, a sentence, propositions, etc. (as true just in case there exists a fact corresponding to it (Wittgenstein, 1922, Austin! 950). This thesis is unexceptionable, however, if it is to provide a rigorous, substantial and complete theory of truth ~ if it is to be more than merely a picturesque way of asserting all equivalences to the form. The belief that p is true p.
Then it must be supplemented with accounts of what facts are, and what it is for a belief to correspond to a fact, and these are the problems on which the correspondence theory of truth has floundered. For one thing, it is far from going unchallenged that any significant gain in understanding is achieved by reducing the belief that snow is white is true to the facts that snow is white exists: For these expressions look equally resistant to analysis and too close in meaning for one to provide a crystallizing account of the other. In addition, the undistributed relationship that holds in particular between the belief that snow is white and the fact that snow is white, between the belief that dogs bark and the fact that a dog barks, and so on, is very hard to identify. The best attempt to date is Wittgenstein's 1922, so-called picture theory, by which an elementary proposition is a configuration of terms, with whatever stare of affairs it reported, as an atomic fact is a configuration of simple objects, an atomic fact corresponds to an elementary proposition and makes it true, when their configurations are identical and when the terms in the proposition for it to the similarly-placed objects in the fact, and the truth value of each complex proposition the truth values entail of the elementary ones. However, eve if this account is correct as far as it goes, it would need to be completed with plausible theories of logical configuration, rudimentary proposition, reference and entailment, none of which is better-off to come.
 The central characteristic of truth One that any adequate theory must explain is that when a proposition satisfies its conditions of proof or verification then it is regarded as true. To the extent that the property of corresponding with reality is mysterious, we are going to find it impossible to see what we take to verify a proposition should show the possession of that property. Therefore, a tempting alternative to the correspondence theory an alternative that eschews obscure, metaphysical concept that explains quite straightforwardly why Verifiability infers, truth is simply to identify truth with Verifiability (Peirce, 1932). This idea can take on variously formed. One version involves the further assumption that verification is holistic, . . . in that a belief is justified (i.e., verified) when it is part of an entire system of beliefs that are consistent and counter balanced (Bradley, 1914 and Hempel, 1935). This is known as the coherence theory of truth. Another version involves the assumption associated with each proposition, some specific procedure for finding out whether one should believe it or not. On this account, to say that a proposition is true is to say that the appropriate procedure would verify (Dummett, 1979. and Putnam, 1981), while mathematics  amounts to the identification of truth with provability.
 The attractions of the verificationist account of truth are that it is refreshingly clear compared with the correspondence theory, and that it succeeds in connecting truth with verification. The trouble is that the bond it postulates between these notions is implausibly strong. We do in true statements take verification to indicate truth, but also we recognize the possibility that a proposition may be false in spite of there being impeccable reasons to believe it, and that a proposition may be true although we are not able to discover that it is. Verifiability and truth are no doubt highly correlated, but surely not the same thing.
 A third well-known account of truth is known as pragmatism (James, 1909 and Papineau, 1987). As we have just seen, the verificationist selects a prominent property of truth and considers the essence of truth. Similarly, the pragmatist focuses on another important characteristic  namely, that true belief is a good basis for action and takes this to be the very nature of truth. True assumptions are said to be, by definition, those that provoke actions with desirable results. Again, we have an account statement with a single attractive explanatory characteristic; besides, it postulates between truth and its alleged analysandum in this case, but utility is implausibly close. Granted, true belief tends to foster success, but it happens regularly that actions based on true beliefs lead to disaster, while false assumptions, by pure chance, produce wonderful results.
 One of the few uncontroversial facts about truth is that the proposition that snow is white if and only if snow is white; the proposition that lying is wrong is true if and only if lying is wrong, and so on. Traditional theories acknowledge this fact but regard it as insufficient and, as we have seen, inflate it with some further principle of the form, X is true if and only if X has property P (such as corresponding to reality, Verifiability, or being suitable as a basis for action), which is supposed to specify what truth is. Some radical alternatives to the traditional theories result from denying the need for any such further specification (Ramsey, 1927, Strawson, 1950 and Quine, 1990). For example, one might suppose that the basic theory of truth contains nothing more that equivalences of the form, the proposition that 'p' is true if and only if 'p' (Horwich, 1990).
 That is, a proposition, 'K' with the following properties, that from 'K' and any further premises of the form. Einstein's claim was the proposition that 'p' you can imply 'p'. Whatever it is, now supposes, as the deflationist says, that our understanding of the truth predicate consists in the simulative decision to accept any instance of the schema. The proposition that 'p' is true if and only if 'p', then your problem is solved. For 'K' is the proposition, Einstein's claim is true; it will have precisely the inferential power needed. From it and Einstein's claim is the proposition that quantum mechanics are wrong, you can use Leibniz's law to imply The proposition that quantum mechanic is wrong is true; which given the relevant axiom of the deflationary theory, allows you to derive Quantum mechanics is wrong. Thus, one point in favours of the deflationary theory is that it squares with a plausible story about the function of our notion of truth, in that its axioms explain that function without the need for further analysis of what truth is.
 Not all variants of deflationism have this quality virtue, according to the redundancy performatives theory of truth, the pair of sentences, The proposition that 'p' is true and plain 'p's', has the same meaning and expresses the same statement as one and another, so it is a syntactic illusion to think that 'p' is true attributes any sort of property to a proposition (Ramsey, 1927 and Strawson, 1950). Yet in that case, it becomes hard to explain why we are entitled to infer The proposition that quantum mechanics are wrong is true form Einstein's claim is the proposition that quantum mechanics are wrong. Einstein's claim is true. For if truth is not property, then we can no longer account for the inference by invoking the law that if X, appears identical with Y then any property of X is a property of Y, and vice versa. Thus the redundancy/performatives theory, by identifying rather than merely correlating the contents of the proposition that p is true and p, precludes the prospect of a good explanation of one on truth most significant and useful characteristics. So, putting restrictions on our assembling claim to the weak is better, of its equivalence schema: The proposition that p is true is and is only p.
 Support for deflationism depends upon the possibleness of showing that its axiom  instances of the equivalence schema unsupplements by any further analysis, will suffice to explain all the central facts about truth, for example, that the verification of a proposition indicates its truth, and that true beliefs have a practical value. The first of these facts follows trivially from the deflationary axioms, for given ours a prior knowledge of the equivalence of ‘p’ and, the  propositions that ‘p’ are true, any reason to believe that ‘p’ becomes an equally good reason to believe that the preposition that p is true. We can also explain the second fact in terms of the deflationary axioms, but not quite so easily. Consider, to begin with, beliefs of the form that if I perform the act ‘A’, then my desires will be fulfilled. Notice that the psychological role of such a belief is, roughly, to cause the performance of ‘A’. In other words, given that I do have belief, then typically.
I will perform the act ‘A’.
Notice also that when the belief is true then, given the deflationary axioms, the performance of ‘A’ will in fact lead to the fulfilment of ones desires, i.e., If being true, then if I perform A, and my desires will be fulfilled.
 Therefore, if it is true, then my desires will be fulfilled. So valuing the truth of beliefs of that form is quite treasonable. Nevertheless, inference has derived such beliefs from other beliefs and can be expected to be true if those other beliefs are true. So assigning a value to the truth of any belief that might be used in such an inference is reasonable.
 To the extent that such deflationary accounts can be given of all the acts involving truth, then the explanatory demands on a theory of truth will be met by the collection of all statements like, The proposition that snow is white is true if and only if snow is white, and the sense that some deep analysis of truth is needed will be undermined.
 Nonetheless, there are several strongly felt objections to deflationism. One reason for dissatisfaction is that the theory has an infinite number of axioms, and therefore cannot be completely written down. It can be described, as the theory whose axioms are the propositions for ‘p’ if and only if it is true that ‘p’, but not explicitly formulated. This alleged defect has led some philosophers to develop theories that show, first, how the truth of any proposition derives from the referential properties of its constituents, and second, how the referential properties of primitive constituents are determinated (Tarski, 1943 and Davidson, 1969). However, assuming that all propositions including belief attributions remain controversial, law of nature and counterfactual conditionals depends for their truth values on what their constituents refer to implicate. In addition, there is no immediate prospect of a presentable, finite possibility of reference, so that it is far form clear that the infinite, list-like character of deflationism can be avoided.
 Additionally, it is commonly supposed that problems about the nature of truth are intimately bound up with questions as to the accessibility and autonomy of facts in various domains: Questions about whether the facts can be known, and whether they can exist independently of our capacity to discover them (Dummett, 1978, and Putnam, 1981). One might reason, for example, that if T is true means nothing more than T will be verified, then certain forms of scepticism, specifically, those that doubt the correctness of our methods of verification, that will be precluded, and that the facts will have been revealed as dependent on human practices. Alternatively, it might be said that if truth were an inexplicable, primitive, non-epistemic property, then the fact that T is true would be completely independent of us. Moreover, we could, in that case, have no reason to assume that the propositions we believe in, that in adopting its property, so scepticism would be unavoidable. In a similar vein, it might be thought that as special, and perhaps undesirable features of the deflationary approach, is that truth is deprived of such metaphysical or epistemological implications.
 Upon closer scrutiny, in that, it is far from clear that there exists any account of truth with consequences regarding the accessibility or autonomy of non-semantic matters. For although an account of truth may be expected to have such implications for facts of the form T is true, it cannot be assumed without further argument that the same conclusions will apply to the fact T. For it cannot be assumed that T and T are true and is equivalent to one another given the account of true that is being employed. Of course, if truth is defined in the way that the deflationist proposes, then the equivalence holds by definition. Nevertheless, if truth is defined by reference to some metaphysical or epistemological characteristic, then the equivalence schema is thrown into doubt, pending some demonstration that the trued predicate, in the sense assumed, will be satisfied in as far as there are thought to be epistemological problems hanging over 'T's' that do not threaten 'T' is true, giving the needed demonstration will be difficult. Similarly, if truth is so defined that the fact, 'T' is felt to be more, or less, independent of human practices than the fact that 'T' is true, then again, it is unclear that the equivalence schema will hold. It would seem, therefore, that the attempt to base epistemological or metaphysical conclusions on a theory of truth must fail because in any such attempt the equivalence schema will be simultaneously relied on and undermined.
 The most influential idea in the theory of meaning in the past hundred yeas is the thesis that meaning of an indicative sentence is given by its truth-conditions. On this conception, to understand a sentence is to know its truth-conditions. The conception was first clearly formulated by Frége (1848-1925), was developed in a distinctive way by the early Wittgenstein (1889-1951), and is a leading idea of Davidson (1917- ). The conception has remained so central that those who offer opposing theories characteristically define their position by reference to it.
 The conceptions of meaning as truth-conditions necessarily are not and should not be advanced as a complete account of meaning. For instance, one who understands a language must have some idea of the range of speech acts conventionally acted by the various types of a sentence in the language, and must have some idea of the significance of various kinds of speech acts. The claim of the theorist of truth-conditions should as an alternative is targeted on the notion of content: If two indicative sentences differ in what they strictly and literally say, then this difference is fully accounted for by the difference in their truth-conditions. Most basic to truth-conditions is simply of a statement that is the condition the world must meet if the statement is to be true. To know this condition is equivalent to knowing the meaning of the statement. Although this sounds as if it gives a solid anchorage for meaning, some of the security disappears when it turns out that the truth condition can only be defined by repeating the very same statement, as a truth condition of snow is white is that snow is white, the truth condition of Britain would have capitulated had Hitler invaded is the Britain would have capitulated had Hitler invaded. It is disputed whether this element of running-on-the-spot disqualifies truth conditions from playing the central role in a substantive theory of meaning. Truth-conditional theories of meaning are sometimes opposed by the view that to know the meaning of a statement is to be able to use it in a network of inferences.
 Whatever it is that makes, what would otherwise be mere sounds and inscriptions into instruments of communication and understanding. The philosophical problem is to demystify this power, and to relate it to what we know of ourselves and the world. Contributions to the study include the theory of speech acts and the investigation of communication and the relationship between words and ideas and the world and surrounding surfaces, by which some persons express by a sentence, are often a function of the environment in which he or she is placed. For example, the disease I refer to by a term like arthritis or the kind of tree I refer to as a Maple will be defined by criteria of which I know next to nothing. The raises the possibility of imagining two persons in alternatively differently environmental, but in which everything appears the same to each of them, but between them they define a space of philosophical problems. They are the essential components of understanding and any intelligible proposition that is true must be capable of being understood. Such that which is expressed by an utterance or sentence, the proposition or claim made about the world may by extension, the content of a predicated or other sub-sentential component is what it contributes to the content of sentences that contain it. The nature of content is the central concern of the philosophy of language.
 In particularly, the problems of indeterminacy of translated, inscrutability of reference, language, predication, reference, rule following, semantics, translated, and the topics referring to subordinate headings associated with logic. The loss of confidence in determinate meaning (Each is another encoding) is an element common both to postmodern uncertainties in the theory of criticism, and to the analytic tradition that follows writers such as Quine (1908- ). Still  it may be asked, why should we suppose that fundamental epistemic notions should be keep an account of for in behavioural terms what grounds are there for supposing that p knows p is a subjective matter in the prestigiousness of its statement between some subject statement and physical theory of physically forwarded of an objection, between nature and its mirror? The answer is that the only alternative seems to be to take knowledge of inner states as premises from which our knowledge of other things is normally implied, and without which our knowledge of other things is normally inferred, and without which knowledge would be ungrounded. However, it is not really coherent, and does not in the last analysis make sense, to suggest that human knowledge have foundations or grounds. It should be remembered that to say that truth and knowledge can only be judged by the standards of our own day is not to say that it is less meaningful nor is it more cut off from the world, which we had supposed. Conjecturing it is as just that nothing counts as justification, unless by reference to what we already accept, and that at that place is no way to get outside our beliefs and our oral communication so as to find some experiment with others than coherence. The fact is that the professional philosophers have thought it might be otherwise, since one and only they are haunted by the clouds of epistemological scepticism.
 What Quine opposes as residual Platonism is not so much the hypostasising of non-physical entities as the notion of correspondence with things as the final court of appeal for evaluating present practices. Unfortunately, Quine, for all that it is incompatible with its basic insights, substitutes for this correspondence to physical entities, and especially to the basic entities, whatever they turn out to be, of physical science. Nevertheless, when their doctrines are purified, they converge on a single claim. That no account of knowledge can depend on the assumption of some privileged relations to reality. Their work brings out why an account of knowledge can amount only to a description of human behavior.
 What, then, is to be said of these inner states, and of the direct reports of them that have played so important a role in traditional epistemology? For a person to feel is nothing else than for him to have an ability to make a certain type of non-inferential report, to attribute feelings to infants is to acknowledge in them latent abilities of this innate kind. Non-conceptual, non-linguistic knowledge of what feelings or sensations are like is attributively to beings on the basis of potential membership of our community. Infants and the more attractive animals are credited with having feelings on the basis of that spontaneous sympathy that we extend to anything humanoid, in contrast with the mere response to stimuli attributed to photoelectric cells and to animals about which no one feels sentimentally. Supposing that moral prohibition against hurting infants is consequently wrong and the better-looking animals are; those moral prohibitions grounded in their possession of feelings. The relation of dependence is really the other way round. Similarly, we could not be mistaken in supposing that a four-year-old child has knowledge, but no one-year-old, any more than we could be mistaken in taking the word of a statute that eighteen-year-old can marry freely but seventeen-year-old cannot. (There is no more ontological ground for the distinction that may suit us to make in the former case than in the later.) Again, such a question as are robots conscious? Calling for a decision on our part whether or not to treat robots as members of our linguistic community. All this is a piece with the insight brought into philosophy by Hegel (1770-1831), that the individual apart from his society is just another animal.
 Willard van Orman Quine, the most influential American philosopher of the latter half of the 20th century, when after the wartime period in naval intelligence, punctuating the rest of his career with extensive foreign lecturing and travel. Quines early work was on mathematical logic, and issued in A System of Logistic (1934), Mathematical Logic (1940), and Methods of Logic (1950), whereby it was with the collection of papers from a Logical Point of View (1953) that his philosophical importance became widely recognized. Quines work dominated concern with problems of convention, meaning, and synonymy cemented by Word and Object (1960), in which the indeterminacy of radical translated first takes centre-stage. In this and many subsequent writings Quine takes a bleak view of the nature of the language with which we ascribe thoughts and beliefs to ourselves and others. These intentional idioms resist smooth incorporation into the scientific world view, and Quine responds with scepticism toward them, not quite endorsing eliminativism, but regarding them as second-rate idioms, unsuitable for describing strict and literal facts. For similar reasons he has consistently expressed suspicion of the logical and philosophical propriety of appeal to logical possibilities and possible worlds. The language those are properly behaved and suitable for literal and true descriptions of the world as those of mathematics and science. The entities to which our best theories refer must be taken with full seriousness in our ontology's, although an empiricist. Quine thus supposes that the abstract objects of set theory are required by science, and therefore exist. In the theory of knowledge Quine associated with a holistic view of verification, conceiving of a body of knowledge in terms of a web touching experience at the periphery, but with each point connected by a network of relations to other points.
 Quine is also known for the view that epistemology should be naturalized, or conducted in a scientific spirit, with the object of investigation being the relationship, in human beings, between the voice of experience and the outputs of belief. Although Quines approaches to the major problems of philosophy have been attacked as betraying undue scientism and sometimes behaviourism, the clarity of his vision and the scope of his writing made him the major focus of Anglo-American work of the past forty years in logic, semantics, and epistemology. As well as the works cited his writings cover The Ways of Paradox and Other Essays (1966), Ontological Relativity and Other Essays (1969), Philosophy of Logic (1970), The Roots of Reference (1974) and The Time of My Life: An Autobiography (1985).
 Coherence is a major player in the theatre of knowledge. There are cogence theories of belief, truth and justification, as these are to combine themselves in the various ways to yield theories of knowledge coherence theories of belief are concerned with the content of beliefs. Consider a belief you now have, the beliefs that you are reading a page in a book, in so, that what makes that belief the belief that it is? What makes it the belief that you are reading a page in a book than the belief that you have a monster in the garden?
 One answer is that the belief has a coherent place or role in a system of beliefs, perception or the having the perceptivity that has its influence on beliefs. As, you respond to sensory stimuli by believing that you are reading a page in a book than believing that you have a monster in the garden. Belief has an influence on action, or its belief is a desire to act, if belief will differentiate the differences between them, that its belief is a desire or if you were to believe that you are reading a page than if you believed in something about a monster. Sortal perceptivals hold accountably the perceptivity and action that are indeterminate to its content if its belief is the action as if stimulated by its inner and latent coherence in that of your belief, however. The same stimuli may produce various beliefs and various beliefs may produce the same action. The role that gives the belief the content it has is the role it plays within a network of relations to other beliefs, some latently causal than others that relate to the role in inference and implication. For example, I infer different things from believing that I am reading a page in a book than from any other belief, justly as I infer about other beliefs.
 The information of perceptibility and the output of an action supplement the central role of the systematic relations the belief has to other belief, but the systematic relations give the belief the specific contentual representation it has. They are the fundamental source of the content of belief. That is how coherence comes in. A belief has the representational content by which it does because of the way in which it coheres within a system of beliefs (Rosenberg, 1988). We might distinguish weak coherence theories of the content of beliefs from stronger coherence theories. Weak coherence theories affirm that coherence is one determinant of the representation given that the contents are of belief. Strong coherence theories of the content of belief affirm that coherence is the sole determinant of the contentual representations of belief.
 When we turn from belief to justification, we confront a similar group of coherence theories. What makes one belief justified and another not? Again, there is a distinction between weak and strong theoretic principles that govern its theory of coherence. Weak theories tell us that the ways in which a belief coheres with a background system of beliefs are one determinant of justification, other typical determinants being perception, memory, and intuitive projection, are, however strong theories, or dominant projections are in coherence to justification as solely a matter of how a belief coheres with a system of latent hierarchal beliefs. There is, nonetheless, another distinction that cuts across the distinction between weak and strong coherence theories between positive and negative coherence theory (Pollock, 1986). A positive coherence theory tells us that if a belief coheres with a background system of belief, then the belief is justifiable. A negative coherence theory tells us that if a belief fails to cohere with a background system of beliefs, then the belief is not justifiable. We might put this by saying that, according to the positivity of a coherence theory, coherence has the power to produce justification, while according to its being adhered by negativity; the coherence theory has only the power to nullify justification.
 A strong coherence theory of justification is a formidable combination by which a positive and a negative theory tell us that a belief is justifiable if and only if it coheres with a background system of inter-connectivity of beliefs. Coherence theories of justification and knowledge have most often been rejected for being unable to deal with an accountable justification toward the perceptivity upon the projection of knowledge (Audi, 1988, and Pollock, 1986), and, therefore, considering a perceptual example that will serve as a kind of crucial test will be most appropriate. Suppose that a person, call her Julie, and works with a scientific instrumentation that has a gauging measure upon temperatures of liquids in a container. The gauge is marked in degrees; she looks at the gauge and sees that the reading is 105 degrees. What is she justifiably to believe, and why? Is she, for example, justified in believing that the liquid in the container is 105 degrees? Clearly, that depends on her background beliefs. A weak coherence theorist might argue that, though her belief that she sees the shape 105 is immediately justified as direct sensory evidence without appeal to a background system, the belief that the location in the container is 105 degrees results from coherence with a background system of latent beliefs that affirm to the shaping perceptivity that its 105 as visually read to be 105 degrees on the gauge that measures the temperature of the liquid in the container. This, nonetheless, of a weak coherence view that combines coherence with direct perceptivity as its evidence, in that the foundation of justification, is to account for the justification of our beliefs.
 A strong coherence theory would go beyond the claim of the weak coherence theory to affirm that the justification of all beliefs, including the belief that one sees the shaping to sensory data that holds accountably of a measure of 105, or even the more cautious belief that one sees a shape, resulting from the perceptivals of coherence theory, in that it coheres with a background system. One may argue for this strong coherence theory in a number of different ways. One through which a medium was to appeal to the coherence theory of contentual representations. If the content of the perceptual belief results from the relations of the belief to other beliefs in a network system of beliefs, then one may notably argue that the justification of perceptivity, that the belief is a resultant from which its relation of the belief to other beliefs, in the network system of beliefs is in argument for the strong coherence theory is that without any assumptive reason that the coherence theory of contentual beliefs, in as much as the supposed causes that only produce the consequences we expect. Consider the very cautious belief that I see a shape. How may the justifications for that perceptual belief are an existent result that is characterized of its material coherence with a background system of beliefs? What might the background system tell us that would justify that belief? Our background system contains a simple and primal theory about our relationship to the world and surrounding surfaces that we perceive as it is or should be believed. To come to the specific point at issue, we believe that we can tell a shape when we see one, completely differentiated its form as perceived to sensory data, that we are to trust of ourselves about such simple matters as whether we see a shape before us or not, as in the acceptance of opening to nature the inter-connectivity between belief and the progression through which is acquired from past experiential conditions of application, and not beyond deception. Moreover, when Julie sees the believing desire to act upon what either coheres with a weak or strong coherence of theory, she shows that its belief, as a measurable quality or entity of 105, has the essence in as much as there is much more of a structured distinction of circumstance, which is not of those that are deceptive about whether she sees that shape or sincerely does not see of its shaping distinction, however. Visible light is good, and the numeral shapes are large, readily discernible and so forth. These are beliefs that Trust has single handedly authenticated reasons for justification. Her successive malignance to sensory access to data involved is justifiably a subsequent belief, in that with those beliefs, and so she is justified and creditable.
 The philosophical; problems include discovering whether belief differs from other varieties of assent, such as acceptance discovering to what extent degrees of belief is possible, understanding the ways in which belief is controlled by rational and irrational factors, and discovering its links with other properties, such as the possession of conceptual or linguistic skills. This last set of problems includes the question of whether prelinguistic infants or animals are properly said to have beliefs.
 Thus, we might think of coherence as inference to the best explanation based on a background system of beliefs, since we are not aware of such inferences for the most part, the inferences must be interpreted as unconscious inferences, as information processing, based on or finding the background system that proves most convincing of acquiring its act and used from the motivational force that its underlying and hidden desire are to do so. One might object to such an account on the grounds that not all justifiable inferences are self-explanatory, and more generally, the account of coherence may, at best, is ably successful to competitions that are based on background systems (BonJour, 1985, and Lehrer, 1990). The belief that one sees a shape competes with the claim that one does not, with the claim that one is deceived, and other sceptical objections. The background system of beliefs informs one that one is acceptingly trustworthy and enables one to meet the objections. A belief coheres with a background system just in case it enables one to meet the sceptical objections and in the way justifies one in the belief. This is a standard strong coherence theory of justification (Lehrer, 1990).
 Illustrating the relationship between positive and negative coherence theories in terms of the standard coherence theory is easy. If some objection to a belief cannot be met in terms of the background system of beliefs of a person, then the person is not justified in that belief. So, to return to Julie, suppose that she has been told that a warning light has been installed on her gauge to tell her when it is not functioning properly and that when the red light is on, the gauge is malfunctioning. Suppose that when she sees the reading of 105, she also sees that the red light is on. Imagine, finally, that this is the first time the red light has been on, and, after years of working with the gauge, Julie, who has always placed her trust in the gauge, believes what the gauge tells her, that the liquid in the container is at 105 degrees. Though she believes what she reads is at 105 degrees is not a justified belief because it fails to cohere with her background belief that the gauge is malfunctioning. Thus, the negative coherence theory tells us that she is not justified in her belief about the temperature of the contents in the container. By contrast, when the red light is not illuminated and the background system of trust tells her that under such conditions that gauge is a trustworthy indicator of the temperature of the liquid in the container, and then she is justified. The positive coherence theory tells us that she is justified in her belief because her belief coheres with her background system of trust tells she that under such conditions that gauge is a trustworthy indicator of the temperature of the liquid in the container, then she is justified. The positive coherence theory tells us that she is justified in her belief because her belief coheres with her background system continues as a trustworthy system.