The idea that Western philosophy is a footnote to Plato is simplistic and inaccurate. Much of modern and contemporary epistemology owes a debt not so much to Platonism or Aristotelianism as to their antithesis: scepticism. Recent discussions in the history of philosophy have sparked a great deal of interest in the ancient sceptics, but until now they have been misunderstood and the significance of their philosophy not fully appreciated.