Arcesilaus (/ˌɑːrsɛsɪˈleɪ.əs/; Greek: Ἀρκεσίλαος; 316/5–241/0 BC) was a Greek Hellenistic philosopher. He was the founder of Academic Skepticism and what is variously called the Second or Middle or New Academy – the phase of the Platonic Academy in which it embraced philosophical skepticism. Arcesilaus succeeded Crates of Athens as the sixth scholarch of the Academy around 264 BC. He did not preserve his thoughts in writing, so his opinions can only be gleaned second-hand from what is preserved by later writers.