Sextus Empiricus' Against the Logicians is by far the most detailed surviving examination by any ancient Greek sceptic of the areas of epistemology and logic. It critically examines the pretensions of non-sceptical philosophers to have discovered methods for determining the truth, either through direct observation or by inference from the observed to the unobserved. It is therefore a fine example of the Pyrrhonist sceptical method at work. It also provides a mine of information about the ideas of other Greek thinkers, ideas that are in many cases poorly preserved in other sources. This volume presents Against the Logicians in a new and accurate translation, together with a detailed introduction that sets the work in its philosophical context.