On Certainty

A sequence of numbered remarks that Wittgenstein wrote in the last year and a half of his life, some only days before his death, published in 1969 by G. E. M. Anscombe and G. H. von Wright with an English translation facing the German. The notes respond to G. E. Moore's papers 'A Defence of Common Sense' and 'Proof of an External World', in which Moore claimed to know such things as 'here is one hand' and that the earth existed long before his birth. Wittgenstein agrees with Moore that we cannot seriously doubt these propositions, but argues that Moore was wrong to say he knows them. Such propositions are not conclusions we have evidence for; they form the framework within which evidence, doubt and knowledge make sense at all. Wittgenstein compares them to the hinges on which questions turn and to a river-bed that channels the flow of thought, and he speaks of a world-picture inherited rather than proved. Doubt itself, he argues, presupposes certainty.

It offers one of the most original responses to scepticism, and its idea of 'hinge' certainties is an active area of epistemology today.