The same conversation is reported as having taken place between Diogenes and Plato, except that instead of ἱππότης and ἀνθρωπότης, we have τραπεζότης and κυαθότης (Diog. L. vi. 53).
We have ζωότης — Ἀθηναιότης — in Galen’s argument against the Stoics (vol. xix. p. 481, Kühn).
First protest of Nominalism against Realism.
This debate between Antisthenes and Plato marks an interesting point in the history of philosophy. It is the first protest of Nominalism against the doctrine of an extreme Realism. The Ideas or Forms of Plato (according to many of his phrases, for he is not always consistent with himself) are not only real existences distinct from particulars, but absorb to themselves all the reality of particulars. The real universe in the Platonic theory was composed of Ideas or Forms such as Manness or Horseness[124] (called by Plato the Αὐτὸ-Ἄνθρωπος and Αὐτὸ-Ἵππος), of which particular men and horses were only disfigured, transitory, and ever-varying photographs. Antisthenes denied what Plato affirmed, and as Plato affirmed it. Aristotle denied it also; maintaining that genera, species, and attributes, though distinguishable as separate predicates of, or inherencies in, individuals — yet had no existence apart from individuals. Aristotle was no less wanting than Antisthenes, in the intellectual eye required for discerning the Platonic Ideas. Antisthenes is said to have declared these Ideas to be mere thoughts or conceptions (ψιλὰς ἐννοίας): i.e., merely subjective or within the mind, without any object corresponding to them. This is one of the various modes of presenting the theory of Ideas, resorted to even in the Platonic Parmenidês, not by one who opposes that theory, but by one seeking to defend it — viz., by Sokrates, when he is hard pressed by the objections of the Eleate against the more extreme and literal version of the theory.[125] It is remarkable, that the objections ascribed to Parmenides against that version which exhibits the Ideas as mere Concepts of and in the mind, are decidedly less forcible than those which he urges against the other versions.
[124] We know from Plato himself (Theætêtus, p. 182 A) that even the word ποιότης, if not actually first introduced by himself, was at any rate so recent as to be still repulsive, and to require an Apology. If ποιότης was strange, ἀνθρωπότης and ἱππότης would be still more strange. Antisthenes probably invented them, to present the doctrine which he impugned in a dress of greater seeming absurdity.
[125] Plato, Parmenidês, p. 132 B. See, afterwards, [chapter xxvii.], Parmenides.
Doctrines of Antisthenes about predication — he admits no other predication but identical.
There is another singular doctrine, which Aristotle ascribes to Antisthenes, and which Plato notices and confutes; alluding to its author contemptuously, but not mentioning his name. Every name (Antisthenes argued) has its own special reason or meaning (οἰκεῖος[126] λόγος), declaring the essence of the thing named, and differing from every other word: you cannot therefore truly predicate any one word of any other, because the reason or meaning of the two is different: there can be no true propositions except identical propositions, in which the predicate is the same with the subject — “man is man, good is good”. “Man is good” was an inadmissible proposition: affirming different things to be the same, or one thing to be many.[127] Accordingly, it was impossible for two speakers really to contradict each other. There can be no contradiction between them if both declare the essence of the same thing — nor if neither of them declare the essence of it — nor if one speaker declares the essence of one thing, and another speaker that of another. But one of these three cases must happen: therefore there can be no contradiction.[128]
[126] Diogen. L. vi. 3. Πρωτός τε ὡρίσατο (Antisthenes) λόγον, εἰπών, λόγος ἐστὶν ὁ τὸ τί ἦν ἤ ἐστι δηλῶν.
[127] Aristotle, Metaphy. Δ. 1024, b. 32, attributes this doctrine to Antisthenes by name; which tends to prove that Plato meant Antisthenes, though not naming him, in Sophist, p. 251 B, where he notices the same doctrine. Compare Philêbus, p. 14 D.