a1 University of Toronto
Kripke's lectures, published as Wittgenstein on Rules and Private Language, posed a sceptical problem about following a rule, which he cautiously attributed to Wittgenstein. He briefly noticed an analogy between his new kind of scepticism and Goodman's riddle of induction. ‘Grue’, he said, could be used to formulate a question not about induction but about meaning:
the problem would not be Goodman's about induction—‘Why not predict that grass, which has been grue in the past, will be grue in the future?’—but Wittgenstein's about meaning: ‘Who is to say that in the past I did not mean grue by “green”, so that now I should call the sky, not the grass, “green”?’.