Outlines of Scepticism, by the Greek philosopher Sextus Empiricus, is a work of major importance for the history of Greek philosophy. It is the fullest extant account of ancient scepticism, and it is also one of our most copious sources of information about the other Hellenistic philosophies. Its first part contains an elaborate exposition of the Pyrrhonian variety of scepticism; its second and third parts are critical and destructive, arguing against ‘dogmatism’ in logic, epistemology, science and ethics - an approach that revolutionized the study of philosophy when Sextus’ works were rediscovered and published in the sixteenth century. This volume presents the accurate and readable translation which was first published in 1994, together with a substantial new historical and philosophical introduction by Jonathan Barnes.