Radical scepticism, epistemological externalism, and closure

Many of the proposals put forward to answer the radical sceptical paradox in the recent literature have involved either blocking the sceptic's highly intuitive use of the 'closure' principle that knowledge is closed under known entailment or, equally implausibly, 'contextualizing' the knowledge operator. In contrast, it is argued here that an externalist theory of knowledge, properly understood, holds the key to meeting the sceptical paradox in a manner that keeps our basic epistemological intuitions intact. In particular, it is shown how, far from failing in sceptical arguments, the sceptic's use of the closure principle is in fact validated by an extemalist epistemology. A diagnosis of the main argument for non-closure offered by Fred Dretske is then given in the light of these remarks.