It is to be observed that a doctrine exactly the same as that which Plato here censures in Antisthenes, will be found maintained by the Platonic Sokrates himself, in Plato, Hippias Major, p. 304 A. See [chap xiii. vol. ii]. of the present work.
[128] Aristot. Topic. i. p. 104, b. 20. θέσις δέ ἐστιν ὑπόληψις παράδοξος τῶν γνωρίμων τινὸς κατὰ φιλοσοφίαν· οἷον ὅτι οὐκ ἔστιν ἀντιλέγειν, καθάπερ ἔφη Ἀντισθένης.
Plato puts this θέσις into the mouth of Dionysodorus, in the Euthydêmus — p. 286 B; but he says (or makes Sokrates say) that it was maintained by many persons, and that it had been maintained by Protagoras, and even by others yet more ancient.
Antisthenes had discussed it specially in a treatise of three sections polemical against Plato — Σάθων, ἢ περὶ τοῦ ἀντιλέγειν, α, β, γ (Diog. L. vi. 16).
The same doctrine asserted by Stilpon, after the time of Aristotle.
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.
[129] Aristotle (Met. Δ. 1024) represents the doctrine of Antisthenes, That contradictory and false propositions are impossible — as a consequence deduced from the position laid down — That no propositions except identical propositions were admissible. If you grant this last proposition, the consequences will be undeniable. Possibly Antisthenes may have reasoned in this way: “There are many contradictory and false propositions now afloat; but this arises from the way in which predication is conducted. So long as the predicate is different from the subject, there is nothing in the form of a proposition to distinguish falsehood from truth (to distinguish Theætêtus sedet, from Theætêtus volat — to take the instance in the Platonic Sophistês — p. 263). There ought to be no propositions except identical propositions: the form itself will then guarantee you against both falsehood and contradiction: you will be sure always to give τὸν οἰκεῖον λόγον τοῦ πράγματος.” There would be nothing inconsistent in such a precept: but Aristotle might call it silly εὐηθῶς), because, while shutting out falsehood and contradiction, it would also shut out the great body of useful truth, and would divest language of its usefulness as a means of communication.
Brandis (Gesch. der Gr. Römisch. Phil. vol. ii. xciii. 1) gives something like this as the probable purpose of Antisthenes — “Nur Eins bezeichne die Wesenheit eines Dinges — die Wesenheit als einfachen Träger des mannichfaltigen der Eigenschaften” (this is rather too Aristotelian) — “zur Abwehr von Streitigkeiten auf dem Gebiete der Erscheinungen”. Compare also Ritter, Gesch. Phil. vol. ii. p. 130. We read in the Kratylus, that there were persons who maintained the rectitude of all names: to say that a name was not right, was (in their view) tantamount to saying that it was no name at all, but only an unmeaning sound (Plato, Krat. pp. 429-430).
[130] Plutarch, adv. Kolôten, p. 1119 C-D.
Nominalism of Stilpon. His reasons against accidental predication.