Academic Skepticism: Arcesilaus and Carneades

Arcesilaus of Pitane (c. 316–241 BCE) became scholarch of Plato's Academy around 268 BCE and, in a striking reversal of the Academy's earlier dogmatic Platonism, redirected it toward systematic skepticism, inaugurating what later historians call the "Middle Academy." His principal target was the Stoic theory of knowledge developed by Zeno of Citium, according to which certain sense impressions are "cognitive" or "cataleptic" (phantasia katalēptikē) — self-evidently and infallibly true, and capable of compelling assent (synkatathesis) from a wise person. Arcesilaus argued, largely through the dialectical method of arguing on both sides of a question (in utramque partem) that he inherited from readings of Plato's aporetic early dialogues, that no impression could be shown to meet this exacting Stoic standard, since for any purportedly cataleptic impression a subjectively indistinguishable false one could in principle occur.