Arcesilaus or Arcesilas Biography

(both forms given in the sources), of Pitane in Aeolia, 316/5–242/1 BC, head of the Academy (the philosophical school founded by Plato) from c.268. In his youth, Arcesilaus studied mathematics with Autolycus at Pitane. His older brother wanted him to study rhetoric, but Arcesilaus escaped to Athens to study philosophy. He first attended the lectures of Theophrastus, but then formed a close friendship with Crantor, whom he followed to the Academy. There he also met Polemon and Crates. On the death of Crates, Socratides, an older member of the school, resigned in favour of Arcesilaus, and he was elected scholarch. Diogenes Laertius' biography (4. 28–45) describes him as a kind and urbane man, respected and admired by his contemporaries.

From the 1st cent. BC on Arcesilaus was known as the founder of the Middle Academy (Diog. Laert. 1. 14; Sext. Emp. Pyr. 1. 220)—the philosopher who introduced scepticism into Plato's school. We do not know whether he was influenced in this by his older contemporary Pyrrhon of Elis, though the famous satirical line of the Stoic Ariston, ‘Plato in front, Pyrrhon behind, in the middle Diodorus’ (Diog. Laert. 4. 33) shows that people recognized some similarities. Arcesilaus, who is said to have owned a private copy of Plato's dialogues, seems to have appealed to the examples of Socrates and Plato. Like Socrates, Arcesilaus would examine or argue against any given thesis and make no assertions of his own. His professed attitude of withholding assent (epochē) was adopted to avoid error and rashness of judgement. Stories about his alleged esotericism, according to which he taught the positive doctrines of Plato to an inner circle of advanced students (Sext. Emp. Pyr. 1. 234; August. contra Academicos3. 20. 43), are certainly later inventions. Arcesilaus published nothing, and what we learn about his arguments must have been handed down in the Academy or through the writings of his opponents.

Arcesilaus' most influential and famous argument was directed against the Stoic theory of knowledge. He argued that given the definition of the Stoic criterion of truth, the so-called cognitive impression (katalēptikē phantasia), one could show that nothing could be grasped or apprehended, since it was impossible to find an impression of such a kind that it could not be false. For any true and clear impression one could describe a situation in which an otherwise indistinguishable impression would be false. Since the Stoics held that the wise man would never assent to a false impression, it followed that the Stoic sage must withhold judgement on all matters. To the Stoic objection that suspension of judgement would make action, and hence life, impossible, Arcesilaus replied that it was possible to act without assenting to anything, and that in the absence of certain knowledge a wise man could be guided by ‘what is reasonable’ (to eulogon).

The thesis that ‘nothing can be grasped’ (akatalēpsia) has been described by ancient as well as modern authors as a doctrine of the sceptical Academy, but this is a mistake: Arcesilaus and his successors down to Carneades insisted that they did not know or assert that nothing could be known, any more than they knew or asserted any other philosophical thesis (Cic. Acad. 1. 45; Acad. post. 28).

Gisela Striker