Carneades

Hellenistic · Africa · 214 to 129 BCE

Greek thinker from Cyrene who led Plato's Academy. He held that we cannot be certain, but can follow what is most convincing.

What it is

Carneades was a Greek philosopher born in Cyrene, a Greek city on the coast of north Africa, around 214 BCE. He went to Athens, studied there, and became head of Plato's Academy, the school Plato had founded. He died around 129 BCE.

He is remembered for arguing that nothing can be known with certainty, and for showing that we can still act sensibly by following what is most convincing. He wrote nothing down. What we know comes from his pupil Clitomachus, whose books were used by later writers such as Cicero and Sextus Empiricus.

The main ideas

No test of truth. He argued that there is no reliable criterion of truth, either in the senses or in reason. Stoic and Epicurean claims to certainty, he said, were inconclusive.
Aiming at the Stoics. The Stoics held that some impressions are so clear that they guarantee the truth of what they show. Carneades argued that a false impression can feel just as clear, so no impression carries such a guarantee.
Holding back assent. If nothing is certain, the sensible course is to suspend judgment instead of declaring something known.
The convincing impression. Without certainty, how can anyone act? Carneades answered that a persuasive impression is enough to act on, even if it may be wrong.
Arguing both sides. His method was to argue on either side of a question.

What it looks like in practice

Imagine someone trying to decide whether a rumour about a neighbour is true. Carneades would not say that nothing can be known, and he would not say that the rumour is certain. He would ask how convincing it is, what supports it, and what each side can say, and then act on the most persuasive account while staying ready to change course. This is an illustration, not a passage from his writing.

Books and moments

The embassy to Rome, 155 BCE. He went with Diogenes the Stoic and Critolaus, head of the school founded by Aristotle, to speak for Athens before the Roman senate.
Two speeches on justice. According to tradition he spoke in defence of justice one day and against it the next.
Teaching by speech. He left no writings, and his influence passed through his pupils.

Questions and criticism

What did he say in Rome? He spoke for justice one day and against it the next. It is fair to ask what he meant by the second speech.
What did he really think? Ancient readers disagreed. His pupil Clitomachus read him as holding back assent completely, while others read him as allowing a weaker approval of what is persuasive.
Softened doubt? Some see the convincing impression as a softening of strict doubt. Was it instead a belief he held, or one more argument aimed at the Stoics?

Close neighbours

The pages on Chrysippus and Zeno of Citium cover the Stoic school he argued against. The page on Plato covers the founder of the Academy he led. The page on Pyrrho covers another ancient school of doubt.

Written by epchē in our own words, and checked against independent sources on 29 October 2026. The sources are listed below.

Who they connect to

Influenced by

Plato · He led the Academy that Plato founded, though he turned it toward doubt.

Other Hellenistic thinkers

Antisthenes · 445 to 365 BCE
Diogenes of Sinope · 412 to 323 BCE
Crates of Thebes · 365 to 285 BCE
Pyrrho of Elis · 360 to 270 BCE
Epicurus · 341 to 270 BCE
Zeno of Citium · 334 to 262 BCE
Cleanthes · 331 to 232 BCE
Chrysippus · 279 to 206 BCE
Cicero · 106 to 43 BCE
Lucretius · 99 to 55 BCE

Sources we used

Carneades · Stanford Encyclopedia of Philosophy, read on 29 October 2026
Carneades · Encyclopaedia Britannica, read on 29 October 2026
Carneades · Wikipedia, read on 29 October 2026