Arcesilaus 316 BC – 241 BC

Arcesilaus of Pitane was a Greek philosopher and the founder of the New, or skeptical, Academy. As head of Plato's school he turned its dialectical method against the dogmatic certainty defended by the Stoics, refusing to assert any positive doctrine of his own. He developed the practice of arguing both sides of every question and the doctrine of suspension of judgment, replacing Stoic kataleptic certainty with what he called the reasonable, to eulogon, as the guide for action. He left no writings; his views are preserved in the reports of Cicero, Sextus Empiricus, and Diogenes Laertius.

Arcesilaus was born around 316 BC at Pitane in Aeolis. He came as a young man to Athens, where after a brief period with the mathematician and Peripatetic philosopher Theophrastus he attached himself to the Platonic Academy under Polemo and Crates. On the death of Crates around 265 BC he succeeded him as head of the Academy, and held the post until his own death some quarter-century later.

Arcesilaus left no writings — a deliberate position consistent with his philosophical style — and his thought is known almost entirely from Cicero, Sextus Empiricus, and Diogenes Laertius. He revived in the Academy the Socratic practice of arguing on both sides of any question, took the position that nothing can be known, and made suspension of assent (epoche) the appropriate response of the wise; he carried on a long polemic against the Stoic doctrine of the cognitive impression as the criterion of truth.

He inaugurated the long phase of academic skepticism that would be carried on by Carneades and Philo of Larissa, and forced the Stoa to refine its epistemology in dialogue with him. Famed for the wit and grace of his teaching, he is reported to have died around 241 BC after a long drinking party.