76. Aenesidemus. -- In his purrôneioi logoi, Aenesidemus (end of first century B.C.) professes in absolute terms a real and universal doubt. He not only rejects the dogmatism of the later academicians, but he even rejects the theory of opinion or probability (69). Neither sense knowledge nor intellectual knowledge can give us any certitude. Aenesidemus drew up his proofs under ten heads, which constitute the classic code of ancient scepticism. Sextus Empiricus subdivides these according as they pertain to the nature of the knowing subject, to the nature of the known object, or to the relation between subject and object. All the objections of Aenesidemus are centred in this fundamental idea: our representations being relative, we can have no criterion of truth. Consequently, we should abstain from all judgment. He himself does not pretend to prove the correctness of his thesis -- that would have been a contradiction -- but merely to give information on our internal condition of mind. His philosophy is not a doctrine (hairesis), but a principle of conduct, a tendency (agôge). His disciples called themselves aporêtikoi, ephektikoi, zêtêtikoi, etc.

In practical life, this attitude of mind is held to produce calmness of soul, happiness. Like the other sceptics, Aenesidemus admits that sensations can serve as a guide for conduct.