ABSTRACT
It has, I hope, become clear that Plato’s complaint about the senses and sensible objects does not stem from the view that if the world was in flux it would be indescribable so that we have to postulate stable meanings for general terms. The point is rather that such a world, while describable would not be one of which episteme was possible. It is not only that sensible objects are not possible subjects for strict ‘is’-es; the predicates appropriate for their straight description cannot be tied by a strict ‘is’ to any subject. This is not to deny that they retain the same meanings but to assert that the accounts of their meanings will make it clear that they attribute modes of change. Since Parmenides it had become in many circles axiomatic that any true proposition must be expressible in the form ‘X is F’ and the ‘is’ be quite unqualified. Greek epistemological scepticism tended therefore to take the form of arguing that unqualified ‘is-’es are impossible, either on the grounds that any X that is F is in some way also not-F, or on the grounds that the world is in constant process and all descriptions are attributions of process. The first tends to the conclusion that any X is only F in relation to something and there is never any general method of settling whether it is F. This can cover a multitude of positions. It might be the claim that nothing is ever good, but only good to Jones (i.e. in his opinion good) or good to Smith. Or it might be the claim that a transaction that is good for Jones is bad for Smith, and there is no question of whether it is good or bad simpliciter (cf. Dialexeis, Diels (1954), II, p. 405). The predicates in which Plato was particularly interested were very susceptible to this sort of treatment, and he was concerned to assert that they could not be subjectivised or relativised in these ways. The second line of attack, from process, claims that the world is such that there is nothing for the stabilising ‘is’ to apply to. Plato wants to hold that such an ‘is’ does have application. It is here that he seems closest to an interest in definition, for definitions certainly seem to contain the sort of timeless ‘is’ sought for. We have seen reason to suppose that it is not just anything that could count as a definition, however. The question remains whether it is right, with regard to the cases in which Plato is interested, to describe his interest as one in the definition of these terms, perhaps allied to a position that some terms are not, in some strict sense, definable.
