I have thus reviewed a long discussion — terminating in a conclusion which appears to me unsatisfactory — of the meaning and function of the negative. I hardly think that Plato would have given such an explanation of it, if he had had the opportunity of studying the Organon of Aristotle. Prior to Aristotle, the principles and distinctions of formal logic were hardly at all developed; nor can we wonder that others at that time fell into various errors which Plato scornfully derides, but very imperfectly rectifies. For example, Antisthenes did not admit the propriety of any predication, except identical, or at most essential, predication: the word ἔστιν appeared to him incompatible with any other. But we perceive in this dialogue, that Plato also did not conceive the substantive verb as performing the simple function of copula in predication: on the contrary he distinguishes ἔστιν, as marking identity between subject and predicate — from μετέχει, as marking accidental communion between the two. Again, there were men in Plato’s day who maintained that Non-Ens (τὸ μὴ ὂν) was inconceivable and impossible. Plato, in refuting these philosophers, gives a definition of Ens (τὸ ὂν), which puts them in the right — fails in stating what the true negative is — and substitutes, in place of simple denial, a second affirmation to overlay and supplant the first.
Doctrine of the Sophistês — contradicts that of other Platonic dialogues.
To complete the examination of this doctrine of the Sophistês, respecting Non-Ens, we must compare it with the doctrine on the same subject laid down in other Platonic dialogues. It will be found to contradict, very distinctly, the opinion assigned by Plato to Sokrates both in the Theætêtus and in the fifth Book of the Republic:[134] where Sokrates deals with Non-Ens in its usual sense as the negation of Ens: laying down the position that Non-Ens can be neither the object of the cognizing Mind, nor the object of the opining (δοξάζων) or cogitant Mind: that it is uncognizable and incogitable, correlating only with Non-Cognition or Ignorance. Now we find that this doctrine (of Sokrates, in Theætêtus and Republic) is the very same as that which is affirmed, in the Sophistês, to be taken up by the delusive Sophist: the same as that which the Eleate spends much ingenuity in trying to refute, by proving that Non-Ens is not the negation of Ens, but only that which differs from Ens, being itself a particular variety of Ens. It is also the same doctrine as is declared, both by the Eleate in the Sophistês and by Sokrates in the Theætêtus, to imply as an undeniable consequence, that the falsehood of any proposition is impossible. “A false proposition is that which speaks the thing that is not (τὸ μὴ ὄν). But this is an impossibility. You can neither know, nor think, nor speak, the thing that is not. You cannot know without knowing something: you cannot speak without speaking something (i. e. something that is).” Of this consequence — which is expressly announced as included in the doctrine, both by the Eleate in the Sophistês and by the Platonic Sokrates in the Theætêtus — no notice is taken in the Republic.[135]
[134] Plato, Republic, v. pp. 477-478. Theætêt. pp. 188-189. Parmenidês, pp. 160 C, 163 C. Euthydêmus, p. 284 B-C.
Aristotle (De Interpretat. p. 21, a. 22) briefly expresses his dissent from an opinion, the same as what is given in the Platonic Sophistês — that τὸ μὴ ὄν is ὄν τι. He makes no mention of Plato, but Ammonius in the Scholia alludes to Plato (p. 129, b. 20, Schol. Bekk.).
We must note that the Eleate in the Sophistês states both opinions respecting τὸ μὴ ὄν: first that which he refutes — next that which he advances. The Scholiast may, therefore, refer to both opinions, as stated in the Sophistês, though one of them is stated only for the purpose of being refuted.
We may contrast with these views of Plato (in the Sophistês) respecting τὸ μὴ ὄν, as not being a negation τοῦ ὄντος, but simply a something ἕτερον τοῦ ὄντος, the different views of Aristotle about τὸ μὴ ὄν, set forth in the instructive Commentary of M. Ravaisson, Essai sur la Métaphysique d’Aristote, p. 360.
“Le non-être s’oppose à l’être, comme sa négation: ce n’est donc pas, non plus que l’être, une chose simple; et autant il y a de genres de l’être, autant il faut que le non-être ait de genres. Cependant l’opposition de l’être et du non-être, différente, en realité, dans chacune des catégories, est la même dans toutes par sa forme. Dans cette forme, le second terme n’exprime pas autre chose que l’absence du premier. Le rapport de l’être et du non-être consiste donc dans une pure contradiction: dernière forme à laquelle toute opposition doit se ramener.”
Aristotle seems to allude to the Sophistês, though not mentioning it by its title, in three passages of the Metaphysica — E. 1026, b. 14; K. 1064, b. 29; N. 1089, a. 5 (see the note of Bonitz on the latter passage) — perhaps also elsewhere (see Ueberweg, pp. 153-154). Plato replied in one way, Leukippus and Demokritus in another, to the doctrine of Parmenides, who banished Non-Ens as incogitable. Leukippus maintained that Non-Ens equivalent to τὸ κενόν, and that the two elements of things were τὸ πλῆρες and τὸ κενόν, for which he used the expressions δὲν and οὐδέν. Plato replied as we read in the Sophistês: thus both he and Leukippus tried in different ways to demonstrate a positive nature and existence for Non-Ens. See Aristot. Metaph. A. 985, b. 4, with the Scholia, p. 538, Brandis. The Scholiast cites Plato ἐν τῇ Πολιτείᾳ, which seems a mistake for ἐν τῷ Σοφίστῃ.
[135] Socher (Ueber Platon’s Schriften, pp. 264-265) is upon this point more satisfactory than the other Platonic commentators. He points out — not only without disguise, but even with emphasis — the discrepancies and contradictions between the doctrines ascribed to the Eleate in the Sophistês, and those ascribed to Sokrates in the Republic, Phædon, and other Platonic dialogues. These are the main premisses upon which Socher rests his inference, that the Sophistês is not the composition of Plato. I do not admit his inference: but the premisses, as matters of fact, appear to me undeniable. Stallbaum, in his Proleg. to the Sophistês, p. 40 seq., attempts to explain away these discrepancies — in my opinion his remarks are obscure and unsatisfactory. Various other commentators, also holding the Sophistês to be a genuine work of Plato, overlook or extenuate these premisses, which they consider unfavourable to that conclusion. Thus Alkinous, in his Εἰσαγωγή, sets down the explanation of τὸ μὴ ὂν which is given in the Sophistês, as if it were the true and Platonic explanation, not adverting to what is said in the Republic and elsewhere (Alkin. c. 35, p. 189 in the Appendix Platonica annexed to the edition of Plato by K. F. Hermann). The like appears in the Προλεγόμενα τῆς Πλάτωνος φιλοσοφίας: c. 21, p. 215 of the same edition. Proklus, in his Commentary on the Parmenidês, speaks in much the same manner about τὸ μὴ ὂν — considering the doctrine advanced and defended by the Eleate in the Sophistês, to represent the opinion of Plato (p. 785 ed. Stallbaum; see also the Commentary of Proklus on the Timæus, b. iii. p. 188 E, 448 ed. Schneid.). So likewise Simplikius and the commentators on Aristotle, appear to consider it — see Schol. ad Aristotel. Physica, p. 332, a. 8, p. 333, b., 334, a., 343, a. 5. It is plain from these Scholia that the commentators were much embarrassed in explaining τὸ μὴ ὄν. They take the Sophistês as if it delivered Plato’s decisive opinion upon that point (Porphyry compares what Plato says in the Timæus, but not what he says in the Republic or in Theætêtus, p. 333, b. 25); and I think that they accommodate Plato to Aristotle, in such manner as to obscure the real antithesis which Plato insists upon in the Sophistês — I mean the antithesis according to which Plato excludes what is ἐναντίον τοῦ ὄντος and admits only what is ἕτερον τοῦ ὄντος.