Five Modes of Scepticism examines the argument forms that lie at the heart of Pyrrhonian scepticism as expressed in the writings of Sextus Empiricus. These are the Agrippan modes of disagreement, hypothesis, infinite regression, reciprocity and relativity; modes which are supposed to bring about that quintessentially sceptical mental state of suspended judgement. Stefan Sienkiewicz analyses how the modes are supposed to do this, both individually and collectively, and from two perspectives. On the one hand there is the perspective of the sceptic’s dogmatic opponent and on the other there is the perspective of the sceptic himself. Epistemically speaking, the dogmatist and the sceptic are two different creatures with two different viewpoints. The book elucidates the corresponding differences in the argumentative structure of the modes depending on which of these perspectives is adopted. Previous treatments of the modes have interpreted them from a dogmatic perspective; one of the tasks of the present work is to reorient the way in which scholars have traditionally engaged with the modes. Sienkiewicz advocates moving away from the perspective of the sceptic’s opponent - the dogmatist - towards the perspective of the sceptic and trying to make sense of how the sceptic can come to suspend judgement on the basis of the Agrippan modes.