Scepticism is a subject which has preoccupied philosophers for two thousand years. This book presents an historical perspective on scepticism by considering contrasting views, such as those of Sextus Empiricus, Descartes and Hume, on why scepticism is important. With its historical perspective and analysis of contemporary discussions, Scepticism provides a broad focus on the subject, differing from other discussions of the topic in the importance it attaches to scepticism both in Greek thought and in pre-twentieth century views generally.