Alan Bailey offers a clear and vigorous exposition and defence of the philosophy of Sextus Empiricus, one of the most influential of ancient thinkers, the father of philosophical scepticism. The subsequent sceptical tradition in philosophy has not done justice to Sextus: his views stand up today as remarkably insightful, offering a fruitful way to approach issues of knowledge, understanding, belief, and rationality.It is widely supposed that any form of scepticism that arrives at a global denial of the availability of rationally justified beliefs is self-refuting and unliveable. Bailey shows that the former objection can be disarmed by distinguishing between the mature Pyrrhonean sceptic's assessment of his negative epistemological arguments and the assessment forced upon his philosophical opponents by their own rationalistic code. The latter objection overlooks the role Sextus allocates to beliefs that are necessitated by the Pyrrhonist's psychological and biological constitution. Alan Bailey's refreshing presentation of Sextus to a modern philosophical readership rescues scepticism from the sceptics.