Arcesilaus

Arcesilaus (Greek: Αρκεσίλαος, ca. 316–241 BCE) was a Greek philosopher and the second scholarch of the Platonic Academy. He succeeded Polemo and led the Academy from roughly 265/260 BCE until his death. He is best known for initiating the era of Academic Skepticism, sometimes called the New Academy, which shifted from a dogmatic interpretation of Platonism toward a skeptical method that emphasized questioning and counterargument rather than firm doctrinal claims.

Arcesilaus' method involved vigorous dialectical disputation: by presenting opposing lines of argument and exposing the difficulties of yielding secure knowledge, he aimed to show that almost any proposition could be defended or refuted. He reportedly refused to commit himself to positive philosophical theses in matters of truth, focusing instead on undermining certainty and urging careful scrutiny of one's beliefs. This approach earned him both praise and criticism and laid the groundwork for later Academic Skeptics such as Carneades and Clitomachus, who elaborated the skeptical program.

Little is known about his personal life or writings; none of his works survive, and our knowledge comes mainly from later sources such as Cicero and Diogenes Laertius. His influence is primarily seen in the formalization of skeptical inquiry within the Platonic tradition, influencing the course of Ancient skeptical philosophy and the broader history of Hellenistic thought.