Carneades

Carneades (214–129 BCE) was the keenest mind of the sceptical Academy, famous for arguing every question with equal force on both sides — most notoriously at Rome, where he praised justice one day and demolished it the next.

Denying that certainty is attainable, he offered instead a theory of the “persuasive” or probable as a guide for life, refining the scepticism of Arcesilaus against the Stoics. He left no writings; his thought survives through his pupils.