Arcesilaus committed nothing to writing. His opinions were imperfectly known to his contemporaries, and can now only be gathered from the statements of later writers. This makes his philosophy difficult to evaluate and partly inconsistent. This led scholars to see his skepticism in several ways. Some see his philosophy as completely negative or destructive of all philosophical views. Others regard him as taking the position that nothing can be known on the basis of his philosophical arguments. Others claimed he held no positive views on any philosophical topic, including the possibility of knowledge. Arcesilaus' contemporary,
Aristo of Chios, described Arcesilaus as being: "
Plato the head of him,
Pyrrho the tail, midway
Diodorus" meaning that Arcesilaus presented himself as a
Platonist, the substance of what he taught was the dialectics of Diodorus, but his actual philosophy was that of
Pyrrhonism.
Eusebius, probably quoting
Aristocles of Messene, reported that Arcesilaus studied in Pyrrho's school and adhered, except in name, to Pyrrhonism.
Numenius of Apamea said "Arcesilaus accompanied
Pyrrho. He remained Pyrrhonist in his rejection of everything, except in name. At least the Pyrrhonists Mnaseas, Philomelos and
Timon call him a Pyrrhonist, just as they were themselves, because he too rejected the true, the false, and the persuasive."
Sextus Empiricus said that Arcesilaus' philosophy appeared essentially the same as Pyrrhonism, but granted that this might have been superficial. On the one hand, Arcesilaus professed to be no innovator, but a reviver of the
dogma-free dialectic that had characterized the academy under Plato. Thus he is said to have restored the doctrines of
Plato in an uncorrupted form. On the other hand, according to
Cicero, he summed up his opinions in the formula, "that he knew nothing, not even his own ignorance." There are two ways of reconciling the difficulty: either we may suppose him to have thrown out such aphorisms as an exercise for his pupils, as
Sextus Empiricus, who calls him a "skeptic", would have us believe; or he may have really doubted the esoteric meaning of Plato, and have supposed himself to have been stripping his works of the figments of the
Dogmatists, while he was in fact taking from them all certain principles. Cicero attributes the following argument to Arcesilaus: (i) it is rash and shameful to assent to something false or unknown, but since (ii) nothing can be known (and obviously we shouldn't do what is rash and shameful), (iii) we should suspend judgment about everything
Zeno of Citium and the other
Stoics were the chief opponents of Arcesilaus. He attacked their
dogma of
katalêptikê phantasia (i.e., a convincing conception) as understood to be a mean between
episteme (knowledge) and
doxa (opinion). He argued that this mean could not exist. It involved a contradiction in terms, as the very idea of
phantasia implied the possibility of false as well as true conceptions of the same object. As such, it was merely the interpolation of a name. ==Commentary on Arcesilaus==