CHAPTER X
THE PLATONIC SCHOOLS

The Laws, which, according to the most probable opinion, was written by Plato, though it was not made public until after his death, bears evidence of the influence which, in the later years of his life, the philosophy of the Pythagoreans exercised on his mind, inclining him to attach more and more importance to the mystic element in philosophy and to the number theory. It was this phase of Platonic thought that was taken up and developed by the Platonic Academies, while in the bands of Aristotle the teachings of the earlier dialogues were carried to a higher development. During the lifetime of Plato there was little, if any, dissension among the members of the school which assembled in the grove of Academus; after Plato's death, however, Aristotle set up a school of his own, in opposition to the members of the Academy, who claimed to possess in their scholarch the authorized head of the Platonic school.

The first scholarch was Speusippus, the nephew of Plato, who, according to Diogenes Laertius,^{1} received his appointment from Plato himself. He in turn was succeeded by Xenocrates,^{2} and in this manner the succession of scholarchs continued down to the sixth century of the Christian era.^{3}

It is customary to distinguish in the history of the Platonic school three periods, known as the Old, the Middle, and the New Academy. To the Old Academy belonged Speusippus, Xenoerates, Heraclides of Pontus, Philip of Opus, Crates, and Crantor; Arcesilaus and Carneades are the principal representatives of the Middle Academy, while Philo of Larissa and Antiochus of Ascalon are the best-known members of the New Academy.

Sources. Our sources of information concerning the history of the doctrines of the three Academies are for the most part secondary; they are scanty and cannot be relied upon in matters of detail. As far, however, as a general characterization of each school is concerned, our materials are sufficiently ample and trustworthy.

Old Academy. The Old Academy flourished from the death of Plato (347 B.C.) until the appearance of Arcesilaus as scholarch (about 250 B.C.). It is distinguished by its interpretation of the Platonic theory of Ideas in accordance with the number theory of the Pythagoreans.

Speusippus seems to have substituted numbers for Ideas, assigning to them all the attributes, including separate existence, which Plato in his earlier dialogues had attributed to the Ideas.^{4} Although, according to Theophrastus, Speusippus devoted but little attention to the study of the natural sciences, on one important point of physical doctrine he differed from Plato, maintaining, if we are to believe our Neo-Pythagorean authorities, that the elements are five, not four, and deriving these five, after the manner of Philolaus, from the five regular figures.^{5} If, as is probable, Aristotle, in Analytica Posteriora, II, 13, 97 a, 6, is speaking of Speusippus, the latter maintained that in order to know anything we must know everything.

Xenocrates continued to combine, as Speusippus had done, the number theory of the Pythagoreans with Plato's doctrine of Ideas. He went farther, however, than Speusippus in his application of number to theological notions, developing a system of demonology which suggests in its elaborateness the doctrines of the Neo-Platonists.

Heraclides of Pontus is remarkable for having taught the diurnal revolution of the earth on its axis, and the immobility of the fixed stars. These views were first proposed by Hicetas of Sicily and by Ecphantus, who was also a Sicilian. Our authorities are Theophrastus^{6} and Plutarch.^{7}

Philip of Opus is generally believed to be the author of Epinomis and the editor of the Laws, of which the Epinomis is a continuation.

Crates and Crantor devoted themselves mainly to the study of ethical problems.

Middle Academy. The Middle Academy was "characterized by an ever-increasing tendency to scepticism." Chronologically, it belongs to the third period of Greek philosophy, and in its spirit and contents it is more in keeping with the post-Aristotelian age than with the time of Plato and Aristotle.

Arcesilaus, who was born about 315 B.C., is regarded as the founder of the Middle Academy. He combated the dogmatism of the Stoics, maintaining that as, according to the Stoics, the criterion of truth is perception, and as a false perception may be as irresistible as a true one, all scientific knowledge is impossible. It is, therefore, he concluded, the duty of a wise man to refrain from giving his assent to any proposition, -- an attitude of mind which the Academicians called forbearance (apoche). Still, Arcesilaus would grant that a degree of probability sufficient for intelligent action is possible.^{8}

Carneades lived from about 210 to 129 B.C. Consequently, he was not the immediate successor of Arcesilaus, whose principles he developed into a more pronounced system of Scepticism. He held that there is no criterion of truth; that what we take to be true is only the appearance of truth, -- phainomenon alêthes which Cicero renders probabile visum.^{9}

New Academy. After the death of Carneades, the Academy abandoned Scepticism and returned to the dogmatism of its founder.

Philo of Larissa and Antiochus of Ascalon introduced into the Academy elements of Stoicism and Neo-Platonism which belong to the third period of Greek philosophy.

Historical Position. The Academics, although they were the official representatives of Platonic philosophy, failed to grasp the true meaning of the theory of Ideas. By introducing Pythagorean and other elements they turned the tradition of the Platonic school out of the line of its natural development, and ended in adopting a scepticism or a dogmatic eclecticism, either of which is far from what should have been the logical outcome of Plato's teaching. They are to Plato what the imperfectly Socratic schools are to Socrates. The continuity, therefore, of Platonic thought is not to be looked for in these schools but rather in the school founded by Aristotle.

{1} IV, 1.

{2} Ibid., IV, 14.

{3} Cf. Ueberweg, op. cit., I, 485 ff.

{4} Arist., Met., VII, 2, 1028 b, 19.

{5} Cf. Zeller, Plato, p. 578, n.

{6} apud Cicero, Acad., II, 39.

{7} Placita, III, 13.

{8} Cf. Cicero, De Orat., III, 13.

{9} Cf. Stöckl, Lehrbuch, I, 173; English trans., Vol. 1, p. 95; Zeller, Stoics, etc., p. 538.