Carneădes in Harpers Dictionary of Classical Antiquities

（Καρνεάδης). A philosopher of Cyrené in Africa, founder of a sect called the Third or New Academy. The Athenians sent him with Diogenes the Stoic, and Critolaüs the Peripatetic, as ambassador to Rome, B.C. 155. Carneades excelled in the vehement and rapid, Critolaüs in the correct and elegant, and Diogenes in the simple and modest, kind of eloquence. Carneades, in particular, attracted the attention of his new anditory by the subtlety of his reasoning and the fluency of his language. Before Galba and Cato the Censor, he harangued with great variety of thought and copiousness of diction in praise of justice. The next day, to establish his doctrine of the uncertainty of human knowledge, he undertook to refute all his former arguments. Many were captivated by his eloquence; but Cato , apprehensive lest the Roman youth should lose their military character in the pursuit of Grecian learning, persuaded the Senate to send back these philosophers, without delay, to their own schools. Carneades obtained such high reputation at home that other philosophers, when they had dismissed their scholars, frequently came to hear him. It was the doctrine of the New Academy that the senses, the understanding, and the imagination frequently deceive us, and therefore can not be infallible judges of truth; but that, from the impression which we perceive to be produced on the mind by means of the senses, we infer appearances of truth or probabilities. He maintained that these do not always correspond to the real nature of things, and that there is no infallible method of determining when they are true or false, and consequently that they afford no certain criterion of truth. Nevertheless, with respect to the conduct of life, Carneades held that probable appearances are a sufficient guide, because it is unreasonable that some degree of credit should not be allowed to those witnesses who commonly give a true report. He maintained that all the knowledge the human mind is capable of attaining is not science, but opinion. He died in B.C. 129. See New Academy.

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