Outlines of Pyrrhonism

A handbook in three books, the fullest surviving account of ancient Pyrrhonian scepticism, written by a Greek doctor whose name links him to the Empiric school of medicine. Book I explains what scepticism is: an ability to set appearances and arguments against one another so that they balance, leading first to suspension of judgement and then, unexpectedly, to tranquillity. Sextus compares this to the painter Apelles, who threw his sponge at a picture in frustration and so achieved the effect he wanted. The sceptic does not live without guidance but follows appearances, natural instincts, feelings, local laws and customs, and the practice of skills. Sextus sets out the Ten Modes, which show how appearances vary with animal, person, sense and circumstance, and the Five Modes: disagreement, infinite regress, relativity, hypothesis and circular reasoning. He explains sceptical phrases such as 'no more this than that'. Books II and III turn these methods on the logic, physics and ethics of the dogmatic schools.

The Five Modes remain one of the strongest challenges any theory of knowledge must meet, and Sextus offers a practical case that suspending judgement can bring peace of mind.