Arcesilaus was a prominent Greek philosopher who lived around 316 to 241 BCE. He was a key figure in the Academy founded by Plato and is known for his contributions to the development of Academic Skepticism. Arcesilaus emphasized the importance of questioning knowledge and believed that certainty was unattainable. He succeeded Polemo as the head of the Academy and introduced a more skeptical approach compared to his predecessors. Arcesilaus argued that while we cannot know anything for certain, we can still make reasonable judgments based on appearances and experiences. His ideas influenced later philosophers, including Cicero and Sextus Empiricus.