Moore and Wittgenstein on knowledge and certainty

In this thesis I examine two responses to systematic scepticism from the school of commonsense and ordinary-language philosophy. In Chapter One I put forward the sceptical challenge via Keith Lehrer's arguments in "Why Not Scepticism." In "A Defense of Commonsense" G. E. Moore counters systematic scepticism by asserting that there are many things that we do in fact know, and in "Proof of an External World," Moore argues that we can easily give proofs for the existence of things which the sceptic maintains are unknowable. In Chapter Two I outline Moore's method of attack on the sceptic and I conclude that Moore's anti-sceptical arguments fail. In On Certainty Wittgenstein dismisses Moore's attempts to directly refute the sceptic. But Wittgenstein claims that there is something special about the propositions which Moore claims to know. Wittgenstein argues that Moore's propositions are certain, where their certainty is related to the fact that it is nonsense for us to be sceptical about them. Unlike Moore, Wittgenstein does not directly engage the sceptic, for Wittgenstein holds that there is no such thing as a meaningful sceptical hypothesis waiting to be engaged. In On Certainty, Wittgenstein takes it upon himself to show why by telling a story which is intertwined with his views on meaning. Chapter Three is meant to provide a clearly drawn road-map of Wittgenstein's sophisticated critique of scepticism. But is Wittgenstein's attempt to dissolve the sceptical hypothesis satisfactory? In Chapter Four I argue that if we view Wittgenstein's attempt to dissolve the sceptical hypothesis as consisting of a set of descriptive statements about language which are justified only in terms of his views of meaning, Wittgenstein's arguments in On Certainty which purport that the scepticism is incoherent are not sufficient to counter Lehrer's sceptical challenge.