Ritter gives an account (Gesch. der Philos. part ii. pp. 288-289) of Plato’s doctrine in the Sophistês respecting Non-Ens; but by no means an adequate account. K. F. Hermann also omits (Geschichte und System der Platonischen Philos. pp. 504-505-507) to notice the discrepancy between the doctrine of the Sophistês, and the doctrine of the Republic, and Theætêtus, respecting τὸ μὴ ὄν — though he pronounces elsewhere that the Republic is among the most indisputably positive of all Plato’s compositions (p. 536).
Again, the doctrine maintained by the Eleate in the Sophistês respecting Ens, as well as respecting Ideas or Forms, is in other ways inconsistent with what is laid down in other Platonic dialogues. The Eleate in the Sophistês undertakes to refute two different classes of opponents; first, the Materialists, of whom he speaks with derision and antipathy — secondly, others of very opposite doctrines, whom he denominates the Friends of Ideas or Forms, speaking of them in terms of great respect. Now by these Friends of Forms or Ideas, Schleiermacher conjectures that Plato intends to denote the Megaric philosophers. M. Cousin, and most other critics (except Ritter), have taken up this opinion. But to me it seems that Socher is right in declaring the doctrine, ascribed to these Friends of Ideas, to be the very same as that which is laid down by Plato himself in other important dialogues — Republic, Timæus, Phædon, Phædrus, Kratylus, &c. — and which is generally understood as that of the Platonic Ideas.[136] In all these dialogues, the capital contrast and antithesis is that between Ens or Entia on one side, and Fientia (the transient, ever generated and ever perishing), on the other: between the eternal, unchangeable, archetypal Forms or Ideas — and the ever-changing flux of particulars, wherein approximative likeness of these archetypes is imperfectly manifested. Now it is exactly this antithesis which the Friends of Forms in the Sophistês are represented as upholding, and which the Eleate undertakes to refute.[137] We shall find Aristotle, over and over again, impugning the total separation or demarcation between Ens and Fientia (εἴδη — γένεσις — χωριστά), both as the characteristic dogma, and the untenable dogma, of the Platonic philosophy: it is exactly the same issue which the Eleate in the Sophistês takes with the Friends of Forms. He proves that Ens is just as full of perplexity, and just as difficult to understand, as Non-Ens:[138] whereas, in the other Platonic dialogues, Ens is constantly spoken of as if it were plain and intelligible. In fact, he breaks down the barrier between Ens and Fientia, by including motion, change, the moving or variable, among the world of Entia.[139] Motion or Change belongs to Fieri; and if it be held to belong to Esse also (by recognising a Form or Idea of Motion or Change, as in the Sophistês), the antithesis between the two, which is so distinctly declared in other Platonic dialogues, disappears.[140]
[136] Socher, p. 266; Schleiermacher, Einleitung zum Sophistes, p. 134; Cousin, Œuvres de Platon, vol. xi. 517, notes.
Schleiermacher gives this as little more than a conjecture; and distinctly admits that any man may easily suppose the doctrine ascribed to these Friends of Forms to be Plato’s own doctrine — “Nicht zu verwundern wäre es, wenn Mancher auf den Gedanken käme, Platon meinte hier sich selbst und seine eigene Lehre,” &c.
But most of the subsequent critics have taken up Schleiermacher’s conjecture (that the Megarici are intended), as if it were something proved and indubitable.
It is curious that while Schleiermacher thinks that the opinions of the Megaric philosophers are impugned and refuted in the Sophistês, Socher fancies that the dialogue was composed by a Megaric philosopher, not by Plato. Ueberweg (Aechtheit der Platon. Schr. pp. 275-277) points out as explicitly as Socher, the discrepancy between the Sophistês and several other Platonic dialogues, in respect to what is said about Forms or Ideas. But he draws a different inference: he infers from it a great change in Plato’s own opinion, and he considers that the Sophistês is later in its date of composition than those other dialogues which it contradicts. I think this opinion about the late composition of the Sophistês, is not improbable; but the premisses are not sufficient to prove it.
My view of the Platonic Sophistês differs from the elaborate criticism on it given by Steinhart (Einleitung zum Soph. p. 417 seq.) Moreover, there is one assertion in that Einleitung which I read with great surprise. Steinhart not only holds it for certain that the Sophistes was composed after the Parmenidês, but also affirms that it solves the difficulties propounded in the Parmenidês — discusses the points of difficulty “in the best possible way” (“in der wünschenwerthesten Weise” (pp. 470-471).
I confess I cannot find that the difficulties started in the Parmenidês are even noticed, much less solved, in the Sophistês. And Steinhart himself tells that the Parmenidês places us in a circle both of persons and doctrines entirely different from those of the Sophistês (p. 472). It is plain also that the other Platonic commentators do not agree with Steinhart in finding the Sophistês a key to the Parmenidês: for most of them (Ast, Hermann, Zeller, Stallbaum, Brandis, &c.) consider the Parmenidês to have been composed at a later date than the Sophistês (as Steinhart himself intimates; compare his Einleitung zum Parmenides, p. 312 seq.). Ueberweg, the most recent enquirer (posterior to Steinhart), regards the Parmenidês as the latest of all Plato’s compositions — if indeed it be genuine, of which he rather doubts. (Aechtheit der Platon. Schrift. pp. 182-183.)
M. Mallet (Histoire de l’École de Megare, Introd. pp. xl.-lviii., Paris, 1845) differs from all the three opinions of Schleiermacher, Ritter, and Socher. He thinks that the philosophers, designated as Friends of Forms, are intended for the Pythagoreans. His reasons do not satisfy me.