Carneades (c. 214-129 B.C.) Born in Cyrene, North Africa. Carneades was a radical sceptic and the first of the philosophers to pronounce the failure of metaphysicians who endeavored to discover rational meanings in religious beliefs. By the time of 159 B.C. he had started to refute all previous dogmatic doctrines, especially Stoicism, and even the Epicureans whom previous sceptics had spared.
Carneades was a student of the stoic Diogenes of Babylon and Hegesinus of Plato's Academy. After the death of Hegesinus around 156/5 BC he took his place in the Academy until 137 BC. He visited Rome as an Athenian official citizen. Among his students are Cleitomachus, Metrodorus, Hagnon of Tarsus and Zenon of Alexandria.
The work of Carneades and his life is known from Diogenes Laertius, Cicero and Sextus Empiricus.
According to Cicero (Lucullus 139) he was a very skilled rhetorician able to support both contrary positions in a discussion (in ultramque partem dicere) such that his students could not decide which position finally was supported by Carneades.
In his visit in Rome he was able to demonstrate his rhetoric ability to the Romans so that he was admired. The result was that Cato the Elder (known to be against the Greeks) tried to force Carneades to return back to Greece (Plutarch, Cato maior xxii 3; Laktanz, Divinae institutiones V 14f.).
He extended the critical comments of the Stoic philosopher Chrysippus about the limitations of knowledge
Carneades rejected idea of the stoic philosophers about the decision method to determine the truth with a rational process "kataleptike phantasia" . He proposed a probabilistic based process (pithané phantasía).