hief objects of
his study, however, were the works of Chrysippus, opposition to whose
views is the mainspring of his philosophy. "If Chrysippus had not been,"
he is reported to have said, "I had not been either." In 155, together
with Diogenes the Stoic and Critolaus the Peripatetic, he was sent on an
embassy to Rome to justify certain depredations committed by the
Athenians in the territory of Oropus. On this occasion he delivered two
speeches on successive days, one in favour of justice, the other against
it. His powerful reasoning excited among the Roman youth an enthusiasm
for philosophical speculations, and the elder Cato insisted on Carneades
and his companions being dismissed from the city.

Carneades, practically a 5th-century sophist, is the most important of
the ancient sceptics. Negatively, his philosophy is a polemic against
the Stoic theory of knowledge in all its aspects. All our sensations are
relative, and acquaint us, not with things as they are, but only with
the impressions that things produce upon us. Experience, he says,
clearly shows that there is no true impression. There is no notion that
may not deceive us; it is impossible to distinguish between false and
true impressions; therefore the Stoic [Greek: phantasia katalaeptikae]
(see STOICS) must be given up. There is no criterion of truth. Carneades
also assailed Stoic theology and physics. In answer to the doctrine of
final cause, of design in nature, he points to those things which cause
destruction and danger to man, to the evil committed by men endowed with
reason, to the miserable condition of humanity, and to the misfortunes
that assail the good man. There is, he concludes, no evidence for the
doctrine of a divine superintending providence. Even if there were
orderly connexion of parts in the universe, this may have resulted quite
naturally. No proof can be advanced to show that this world is anything
but the product of natural forces. Carneades further attacked the very
idea of God. He points out the contradiction between the attributes of
infinity and individuality. Like Aristotle, he insists that virtue,
being relative, cannot be ascribed to God. Not even intelligence can be
an attribute of the divine Being. Nor can he be conceived of as
corporeal or incorporeal. If corporeal, he must be simple or compound;
if a simple and elementary substance, he is incapable of life and
thought; if compound, he contains in himself the elements of
dissol