ABSTRACT
Michael Williams's magisterial book on Cartesian radical scepticism, Unnatural Doubts, is one of the most important works in epistemology, if not philosophy, more generally, of the last fifty years. Wittgenstein is suggesting that doubt of that which is optimally certain cannot be rational because it throws into question one's entire system of beliefs and thus the very putative rational basis of the doubt itself. Wittgenstein is suggesting that doubt of that which is optimally certain cannot be rational because it throws into question one's entire system of the beliefs and thus the very putative rational basis of the doubt itself. Williams further argues that the Cartesian sceptical problem essentially trades on the idea that fully general rational evaluations are possible and hence, that a rejection of the totality condition is thereby a rejection of this form of the radical scepticism.
