 Philo (159/8–84/3 BCE) was the last known head of Plato’s Academy during its skeptical phase. Under his leadership, the Academics abandoned the radical skepticism of Arcesilaus and Carneades (who professed to live without rationally warranted beliefs) in favor of a form of mitigated skepticism allowing for provisional beliefs that did not claim certainty. But Philo himself seems to have gone a step further in his controversial “Roman Books”, where he rejected the Stoic definition of knowledge on which the Academics’ mitigated skepticism relied. The evidence suggests that he proposed instead a weaker, fallibilist theory that allowed for ordinary knowledge but did not support the theoretical dogmatism of the Academics’ philosophical rivals. By challenging the accepted epistemological framework of the Hellenistic period, Philo thus inadvertently helped to set the stage for the subsequent revival of Platonism as a dogmatic tradition based on the interpretation of Platonic doctrines. He is most widely known, however, as the teacher of Cicero, through whose work Academic skepticism became known in the Latin-reading world.