Sextus Empiricus c. 160 – c. 210

Sextus Empiricus was a Greek physician and philosopher of the second and early third centuries AD, the principal extant source for ancient Pyrrhonian Skepticism. His major works, the Outlines of Pyrrhonism and Against the Mathematicians (also known as Against the Professors), set out the Pyrrhonian method and apply it systematically to the dogmatic claims of grammarians, rhetoricians, geometers, arithmeticians, astrologers, musicians, logicians, physicists, and ethicists. The Skeptical method he describes consists in opposing argument to argument, suspending judgement on every disputed question, and so attaining tranquillity. The recovery of his works in the 16th century, particularly the Latin translation of the Outlines published in 1562, was decisive in launching the modern Skeptical tradition that runs through Montaigne to Hume. Almost nothing else is known of his life.

Sextus Empiricus was a Greek physician and Pyrrhonist philosopher who flourished in the late second and early third centuries AD. Almost nothing is known of his life with certainty: his name suggests an affiliation with the Empiric school of medicine, although his own medical remarks have been read as Methodic; he may have taught at Alexandria, Athens, or Rome. He is the principal voice after Aenesidemus of the late Pyrrhonist tradition.

His extant works are the three books of the Outlines of Pyrrhonism, a systematic introduction to sceptical practice; the five books Against the Logicians, the Physicists, and the Ethicists, today usually grouped together as Against the Dogmatists; and the six books Against the Professors, addressed to the practitioners of the liberal arts. Together they form by far the most extensive surviving exposition of ancient scepticism.

Sextus codified the sceptical practice of opposing every claim with an equipollent counter-claim until the mind, unable to assent, suspends judgement and arrives at ataraxia, the tranquillity for whose sake the sceptic originally set out to enquire. His ten and five 'modes' of suspension and his patient demolition of dogmatic logic, physics, and ethics gave Renaissance humanists their first detailed access to scepticism and through Montaigne and Descartes shaped the entire modern tradition. He is presumed to have died around AD 210.