Carneades was a Greek philosopher from the city of Cyrene, active in the 3rd century BCE. He is best known as a prominent figure in the Academic Skepticism school of thought, which questioned the possibility of certain knowledge. Carneades argued that humans cannot attain absolute truth and emphasized the importance of considering multiple perspectives. His most famous contribution is the idea of "probabilism," which suggests that beliefs should be based on the likelihood of their truth rather than certainty. Carneades also engaged in debates about ethics and justice, influencing later philosophers, including Cicero and Plato.