1911 Encyclopædia Britannica/Arcesilaus
ARCESILAUS (316–241 B.C.), a Greek philosopher and founder of the New, or Middle, Academy (see Academy, Greek). Born at Pitane in Aeolis, he was trained by Autolycus, the mathematician, and later at Athens by Theophrastus and Crantor, by whom he was led to join the Academy. He subsequently became intimate with Polemon and Crates, whom he succeeded as head of the school. Diogenes Laërtius says that he died of excessive drinking, but the testimony of others (e.g. Cleanthes) and his own precepts discredit the story, and he is known to have been much respected by the Athenians. His doctrines, which must be gathered from the writings of others (Cicero, Acad. i. 12, iv. 24; De Orat. iii. 18; Diogenes Laërtius iv. 28; Sextus Empiricus, Adv. Math. vii. 150, Pyrrh. Hyp. i. 233), represent an attack on the Stoic φαντασία καταληπτική (Criterion) and are based on the sceptical element (see Scepticism) which was latent in the later writings of Plato. He held that strength of intellectual conviction cannot be regarded as valid, inasmuch as it is characteristic equally of contradictory convictions. The uncertainty of sensible data applies equally to the conclusions of reason, and therefore man must be content with probability which is sufficient as a practical guide. “We know nothing, not even our ignorance”; therefore the wise man will be content with an agnostic attitude. He made use of the Socratic method of instruction and left no writings. His arguments were marked by incisive humour and fertility of ideas.