SEXTUS EMPIRICUS. - Skeptical philosopher and physician, who lived in the second half of the 2nd century AD. He belonged to the school of "empiricist" physicians, whence his appellation. Nothing is known of his life: it is conjectured that he was African from the fact that Suidas lists some of his works under the name of a "S. Libycus."
Of S. E. there remain — his medical writings being lost — three works of the greatest value for the knowledge of Greek skepticism (v.), of which S. represents, after Aenesidemus and Agrippa, the last phase. In the Πυρρώνειαι ὑποτυπώσεις there is traced, as the title says, a fundamental sketch of Pyrrhonism (v.); Book I contains a treatment of the conceptual principles and of the method of the school; Books II and III are devoted to the confutation of dogmatism (v.). In the five books Πρὸς θνηματικός the same polemic against the "logicians," the "physicists," and the "ethicists" is developed at length. The six books Against the Learned (to which in the manuscripts the preceding ones are joined, under the common title of Πρὸς μαθηματικός) subject to skeptical criticism all the representatives of science not properly philosophical — mathematicians, astrologers, grammarians, etc.
S. E. is not original, but he sets forth in clear, though somewhat prolix, form the doctrines of his masters, and can be used as a source, albeit with great caution, also for obtaining information about his dogmatic adversaries.