Meaning and verification

The verifiability theory of meaning says that meaning is evidence. It is anticipated in, for example, Hume’s empiricist doctrine of impressions and ideas, but it emerges into full notoriety in twentieth-century logical positivism. The positivists used the theory in a critique of metaphysics to show that the problems of philosophy, such as the problem of the external world and the problem of other minds, are not real problems at all but only pseudoproblems. Their publicists used the doctrine to argue that religion, ethics and fiction are meaningless, which is how verificationism became notorious among the general public.

Seminal criticism of verification from around 1950 argues that no division between sense and nonsense coincides tidily with a division between science and metaphysics, as the positivists had claimed. Quine later developed verificationism into a sort of semantic holism in which metaphysics is continuous with science. In contrast, Dummett argues from a reading of Wittgenstein’s claim that meaning is use to a rejection of any sort of truth surpassing the possibility of knowledge, and thence to a defence of intuitionistic logic. But the claim that all truths can be known yields in an otherwise innocuous setting the preposterous consequence that all truths actually are known. There are ways to tinker with the setting so as to avoid this consequence, but it is best to conclude by reductio that some truths cannot be known and that verificationism is false. That in turn seems to show that the prospects for an empiricist theory of meaning are dim, which might well shake a complacent confidence in meaning.