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 Laertius 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 Oral. iii. r8; Diogenes Laertius iv . 28; Sextus Empiricus, Adv . Math. vii . 150, Pyrrh . Hyp. i .

233), represent an attack on the Stoic cxavracia KaTaXII1rTIK1] (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 . See R . Brodeisen, De Arcesila philosopho (1821); Aug . Geffers, De Arcesila (1842); Ritter and Preller, Hist. phiios. grace . (1898); Ed . Zeller, Phil. d . Griech .

(iii . 1448) ; and

general works under SCEPTICISM .