Plato and the Other Companions of Sokrates, 3rd ed. Volume 1

Though Antisthenes and Diogenes laid chief stress upon ethical topics, yet they also delivered opinions on logic and evidence.122 Antisthenes especially was engaged in controversy, and seemingly in acrimonious controversy, with Plato; whose opinions he impugned in an express dialogue entitled Sathon. Plato on his side attacked the opinions of Antisthenes, and spoke contemptuously of his intelligence, yet without formally naming him. At least there are some criticisms in the Platonic dialogues (especially in the Sophistês, p. 251) which the commentators pronounce, on strong grounds, to be aimed at Antisthenes: who is also unfavourably criticised by Aristotle. We know but little of the points which Antisthenes took up against Plato and still less of the reasons which he urged in support of them. Both he and Diogenes, however, are said to have declared express war against the Platonic theory of self-existent Ideas. The functions of general Concepts and general propositions, together with the importance of defining general terms, had been forcibly insisted on in the colloquies of Sokrates; and his disciple Plato built upon this foundation the memorable hypothesis of an aggregate of eternal, substantive realities, called Ideas or Forms, existing separate from the objects of sense, yet affording a certain participation in themselves to those objects: not discernible by sense, but only by the Reason or understanding.

These bold creations of the Platonic fancy were repudiated by Antisthenes and Diogenes: who are both said to have declared “We see Man, and we see Horse; but Manness and Horseness we do not see”. Whereunto Plato replied “You possess that eye by which Horse is seen: but you have not yet acquired that eye by which Horseness is seen”.123

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 Horseness124 (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.

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 (οἰκεῖος126 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

The works of Antisthenes being lost, we do not know how he himself stated his own doctrine, nor what he said on behalf of it, declaring contradiction to be impossible. Plato sets aside the doctrine as absurd and silly; Aristotle — since he cites it as a paradox, apt for dialectical debate, where the opinion of a philosopher stood opposed to what was generally received — seems to imply that there were plausible arguments to be urged in its favour.129 And that the doctrine actually continued to be held and advocated, in the generation not only after Antisthenes but after Aristotle — we may see by the case of Stilpon: who maintained (as Antisthenes had done) that none but identical propositions, wherein the predicate was a repetition of the subject, were admissible: from whence it followed (as Aristotle observed) that there could be no propositions either false or contradictory. Plutarch,130 in reciting this doctrine of Stilpon (which had been vehemently impugned by the Epikurean Kolôtês), declares it to have been intended only in jest. There is no ground for believing that it was so intended: the analogy of Antisthenes goes to prove the contrary.

Stilpon, however, while rejecting (as Antisthenes had done) the universal Ideas131 or Forms, took a larger ground of objection. He pronounced them to be inadmissible both as subject and as predicate. If you speak of Man in general (he said), what, or whom, do you mean? You do not mean A or B, or C or D, &c.: that is, you do not mean any one of these more than any other. You have no determinate meaning at all: and beyond this indefinite multitude of individuals, there is nothing that the term can mean. Again, as to predicates — when you say, The man runs, or The man is good, what do you mean by the predicate runs, or is good? You do not mean any thing specially belonging to man: for you apply the same predicates to many other subjects: you say runs, about a horse, a dog, or a cat — you say good in reference to food, medicine, and other things besides. Your predicate, therefore, being applied to many and diverse subjects, belongs not to one of them more than to another: in other words, it belongs to neither: the predication is not admissible.132