Christopher Peacocke

Understanding statements containing the past tense involves tacit knowledge of the generalization of such principles as this: ‘Yesterday it rained’ is true if and only if yesterday had the same property as today is required to have for a present‐tense thought ‘It is now raining’ to be true when evaluated with respect to today. This is a variant of the truth‐value link. This tacit knowledge integrates with realism about the past because present‐tense statements are as categorical as their past‐tense counterparts and cannot be reduced to counterfactuals without circularity. An externalist model of the perception of temporal properties and relations can be given, one involving a constitutive sensitivity to instances of those temporal properties and relations themselves. This can contribute to an explanation of how memory supplies knowledge of the past.

States and defends the second principle of rationalism, The Rationalist Dependence Thesis, which holds that the rational truth‐conduciveness of any given transition to which a thinker is entitled is to be philosophically explained in terms of the nature of the intentional contents and states involved in the transition. The second principle, therefore, explains what it means for a transition to lead to true judgements in ‘a distinctive way characteristic of rational transitions’: if the reliability of that transition can be seen to follow from the nature of those contents and states, then the transition is one to which the thinker is entitled. The remainder of Ch. 2 elucidates and paves the way for the author's argument for the Rationalist Dependence Thesis: the author identifies two tasks for a rationalist to support the thesis for content‐endorsing transitions, namely to show why the content of perceptual entitling states will tend to be true and to show why the transition to the judgement of the content made rational by the entitling perceptual state is truth‐conducive when the entitling state has a correct content. The first task is judged to be the greater challenge and three levels of the entitlement relation are distinguished from one another, each level differing from the others in terms of generality and explanatory power.

Some concepts can be individuated partly or wholly in terms of the conditions for knowing certain contents containing those concepts. For these concepts, the conditions for outright judgement mentioned in their possession conditions suffice both for the truth of the contents in question and for the knowledge of those contents. Proper analysis of these conditions provides a means of meeting the Integration Challenge in cases in which the Linking Thesis holds. The model of constitutive causal sensitivity and the model of implicitly known principles are distinguished. Indicators of which model is appropriate for a given domain include a priori status, the role of causal explanation of knowledgeable judgement about the domain, and the role of principles concerning the identity of properties.

The Integration Challenge is the task of reconciling a plausible account of what is involved in the truth of statements of a given kind with a credible account of how we can know those statements, when we do know them. Reconciliation in a given domain may be achieved by re‐conceiving the metaphysics of that domain, or its epistemology, or both. More radically, reconciliation may involve offering slimmed‐down truth conditions, or abandoning the notion of truth conditions altogether for the domain. Options that reject the possibility of integration are scepticism and the denial that an apparent domain involves any genuine subject matter at all. Illustrations of these strategies are given in the cases of necessity, the past, self‐knowledge, and freedom of the will.

A conscious occurrent propositional attitude contributes to the content of consciousness by occupying attention, rather than by being its object. Externally individuated concepts contribute to the nature of this conscious occupation of attention. Those same externally individuated concepts are redeployed when the occurrence of these conscious states gives a subject a reason for self‐ascribing a propositional attitude. This account, involving both conscious states and conceptual redeployment, steers a middle course between accounts of self‐ascription that involve introspection and those accounts under which a subject does not have reasons when she makes such a self‐ascription.

Thinkers who have postulated a transcendental subject of experience have responded to an epistemological insight about first‐person thought with a metaphysical error. The distinctive features of the first person that has produced the illusion is not immunity to error through misidentification, but a certain kind of representational independence. Representationally independent uses of the first person are those in which the thinker rationally forms a present‐tense first‐person belief, but not by endorsing the content of some conscious state, which itself has a first‐person representational content. Mis‐characterization of this phenomenon provides an explanation of the source of the illusion that there is a transcendental subject of experience.

Argues for the thesis that basic moral principles are known to us a priori. The author argues that such moral principles have epistemic characteristics that are incompatible with all recent mind‐dependent, expressivist, and subjectivist treatments of moral thought. He elucidates these characteristics and argues for their incompatibility with many recent treatments in moral philosophy. The author further proposes a better theory, a moderate moral rationalism, which can explain the epistemic characteristics in question, and discusses what he calls the Subjectivist Fallacy, which is, according to the author, largely responsible for making mind‐dependent views of morality seem more attractive than they really are, and to which consequently much recent writing in the area has succumbed.

The penultimate chapter of The Realm of Reason discusses the relation between the author's moral rationalism and a thorough moral realism and the question of whether a moral rationalist can hold that moral properties are sometimes involved in causal explanations. In reply, The author introduces what he calls the Eirenic Combination, which holds that causal explanation of a priori moral beliefs by moral facts is excluded by the a priori status of those beliefs; but this is compatible with the moral properties mentioned in the a priori principles playing a significant part in empirical explanations, which they sometimes do. He then defends his moral rationalism against the charge that it is incompatible with the extensive role moral emotions play in our ordinary first‐level moral thought.

There is a set of principles, the Principles of Possibility, that constrains whether a description picks out a genuinely possible world. To grasp the concept of metaphysical necessity is to have tacit knowledge of this set of Principles and to apply them in evaluating modal statements and thoughts. For a statement to be necessary is for it to hold in all descriptions that are not excluded as possible by the principles of possibility. This integrates the metaphysics and epistemology of necessity, without collapsing into mind‐dependence and without a commitment to modal realism. The treatment of the metaphysics validates the modal systems T and S4.

Argues that the same principles of complexity reduction that he used to explain principles of perceptual entitlement in the preceding chapter can be used to explain the principles of inductive inference. When we have a sound, non‐conclusive inductive inference from a variety of Fs being G to the conclusion that all Fs are G, this holds because the easiest way for the evidence to hold is one that also makes it the case that all Fs are G. Clarifies and elaborates this thesis and traces out its consequences.

States and defends the first principle of rationalism, The Special Truth‐Conduciveness Thesis, which illustrates the connection between entitlement to form a given belief and the belief's truth. The principle holds that a fundamental and irreducible part of what makes a transition one to which a thinker is entitled is that the transition tends to lead to true judgements in a distinctive way characteristic of rational transitions. The author then defends this principle and its commitments against a variety of challenges, notably against two extreme views on the role the notion of evidence plays in the individuation of concepts and meanings. On one view evidence has no part at all to play in the individuation of concepts, and on the other, Quinean, view meanings are not merely partially, but exclusively a matter of certain evidential relations. The author challenges both views and suggests a middle way which his Generalised Rationalism is able to tread.

A reflective person is free to do something just in case there is a close possibility in which he tries to do it, and he would do it if he tried to. On this account, it can be shown that this inference is invalid: ‘If someone is not free not to be F, and it is causally necessary that if he is F, then he is G, then: he is not free not to be G’. This account of freedom is compatibilist, and attributions of freedom involve a substantive metaphysical commitment, rather than being a non‐factual or practical matter.

The objectivity of some area of thought can often be acknowledged without postulating an exotic metaphysics. Statements that may seem to be the merest truisms may have previously hidden metaphysical or epistemological significance. No conclusions about the mind‐dependence of some subject matter can be drawn from the fact that in certain circumstances, it is a priori that a thinker will be right about that subject matter. The notion of an implicit conception with a certain content looms large in an account of understanding. We can learn more about metaphysics and epistemology by considering them not in isolation, but in the light of the relations they must bear to one another.

States and defends the third principle of rationalism, The Generalised Rationalist Thesis, which holds that all instances of the entitlement relation, both absolute and relative, are fundamentally a priori. Even if a thinker's entitlement to a transition is provided by certain experiences of hers, her entitlement to make that transition from those experiences cannot itself be provided by certain experiences of hers. The author defends the third principle by appeal to two considerations: first, if the epistemological significance of experience was itself not knowable a priori, then making any particular transition on the basis of that experience could not be rational, and so a thinker could not be entitled to make that transition. Thus, if we are to be entitled to make any transition on the basis of experience, the principle that entitles us to make that transition must be knowable a priori, whether or not we happen to know it. The second consideration in defence of the third principle rests on a general conception of what it is for a proposition or transition to be a priori. According to this conception, a proposition or transition is a priori just in case its truth or truth‐conduciveness can be explained from the nature of its content, or of the states that it involves. According to this conception, the third principle is a corollary of the first two principles, and so our defence of those two principles should serve to defend the third principle as well.

The principal thesis of A Study of Concepts is that a concept is individuated by its possession condition. Concepts are here understood to be sliced as finely as epistemic possibility. So now and 6 o’clock are different concepts, even if, in context, they pick out the same time; likewise for the observational concept circular and the complex concept locus of coplanar points equidistant from a given point. In the simplest cases, a possession condition is stated by giving a true, individuating statement of the form.

Only computational explanations of a content‐involving sort can answer certain ‘how’‐questions; can support content‐involving counterfactuals; and have the generality characteristic of psychological explanations. Purely formal characteriza‐tions of computations have none of these properties, and do not determine content. These points apply not only to psychological explanation, but to Turing machines themselves. Computational explanations which involve content are not opposed to naturalism. They are also required if we are to explain the content‐involving properties of mental states.

This paper has five theses, which are intended to address the claims in Jerry Fodor's paper. (1) The question arises of the relation between the philosophical theory of concepts and epistemology. Neither is explanatorily prior to the other. Rather, each relies implicitly on distinctions drawn from the other. To explain what makes something knowledge, we need distinctions drawn from the theory of concepts. To explain the attitudes mentioned in a theory of concepts, we need to use the notion of knowledge. (2) Concepts can have a normative dimension without their nature being interpretation‐dependent, and without their nature being mind‐dependent. The normative dimension traces back instead to the role of truth as a constitutive aim of judgement. (3) Conceptual combination is to be explained at the level of reference and semantic value. When we respect this fact, there is no difficulty in explaining compositionality for epistemically‐constrained concepts. (4) Epistemically‐constrained theories of concepts are committed to the applicability of the notion of the a priori. They are not committed to the applicability of the notion of analyticity, where this is construed as truth purely in virtue of meaning or the identity of concepts. (5) Possession of a concept has causal‐explanatory powers, whether given by a possession condition in the form presented in A Study of Concepts, or by possession of an implicit conception. A possession‐condition theory of concepts need not be a form of dispositionalism.