Christopher Peacocke

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.

The topic of Being Known is what I call the Integration Challenge, which is the challenge of providing, for any given domain, a simultaneously acceptable metaphysics and epistemology for that domain. In virtually every domain of thought, it is a substantive task to reconcile our metaphysics and our epistemology of that domain. In some cases, we have an intuitively acceptable metaphysics, but cannot find a plausible epistemology which would allow us knowledge of truths for which that is the right metaphysics. In others, the reverse situation obtains. In yet others, we have an intuitive metaphysics and an intuitive epistemology, but cannot see how they are to be reconciled.