The Classical Theory of Mind I

Abstract

The Classical Theory of Mind stands and falls with a certain account of propositional logical modality: namely, the account in terms of clear and distinct ideas, which we shall elaborate in detail in this chapter. In modern Analytic Philosophy, there have been roughly four kinds of account of logical modality on offer. Firstly, the best known of these is the account in terms of possible worlds, according to which a proposition is, say, logically true just in case it is true in all possible worlds. Secondly, logicians have often favoured the account in terms of deducibility in a formal system, according to which a proposition is logically true just in case it is deducible as a theorem in such-and-such an axiomatic or deductive system. Thirdly, linguistically orientated philosophers have tended to think of logical or necessary truth as a matter of mere linguistic-cum-behavioural convention and resistance to revision. Fourthly, very much out of favour has been the notion that a proposition is analytically or logically true just in case it is true by virtue of its meaning. The first three accounts have been characteristic of Analytic Philosophy, and have been often inter-mingled: not uncommonly a philosopher and logician would hold that necessary truth is both a matter of truth in all possible worlds and of deducibility, and that it is all but a behavioural convention. The fourth account has been typically seen as the Conservative mentalistic position, and as irrevocably defeated by Quine’s (1951) attack on the analytic-synthetic distinction. The CTM approach we are about to embark on, in terms of clear and distinct ideas, could be regarded as spelling out the allegedly discredited notion of analytic truth as truth by virtue of meaning. But I am not happy to regard it so; not because I would again have to combat Quine (for that would not be too difficult), but because the notion of analyticity as truth by virtue of meaning is so truncated as to be a foregone conclusion. In general, Quine’s notions of classical mentalism — that the meaning of a word is an idea in the mind, that an analytic truth is truth by virtue of meaning, a synthetic truth is truth by virtue of fact, that ‘the a priori’ is knowledge independent of experience, ‘the a posteriori’ knowledge dependent on experience, and so forth — are left in so poor a state it is impossible to make any coherent sense of them. Rather than being embroiled in such notions, I will turn to the Classical Theory of Mind itself; and, in order to make its exposition as plain as possible, I will design in this chapter a simple formal model of CTM, in which the mentalistic notions of meaning and logical modality can be clearly investigated.