Those who, like Socher, deny Plato's authorship of the Parmenidês, on the ground of what is urged therein against the theory of Ideas, must suppose, either that he did not know that a negative case could be made out against that theory; or that knowing it, he refrained from undertaking the duty.[27] Neither supposition is consistent with what we know both of his negative ingenuity, and of his multifarious manner of handling.
[Footnote 27: Plato, Philêbus, p. 14, where the distinction taken coincides accurately enough with that which we read in Plato, Parmenid. p. 129 A-D.
Strümpell thinks that the Parmenidês was composed at a time of Plato's life when he had become sensible of the difficulties and contradictions attaching to his doctrine of self-existent Forms or Ideas, and when he was looking about for some way of extrication from them: which way he afterwards thought that he found in that approximation to Pythagorism--that exchange of Ideas for Ideal numbers, &c.--which we find imputed to him by Aristotle (Gesch. der Griech. Phil. sect. 96, 3). This is not impossible; but I find no sufficient ground for affirming it. Nor can I see how the doctrine which Aristotle ascribes to Plato about the Ideas (that they are generated by two [Greek: stoichei=a] or elements, [Greek: to\ e(/n] along with [Greek: to\ me/ga kai\ to\ mikro/n]) affords any escape from the difficulties started in the Parmenidês.
Strümpell considers the dialogue Parmenidês to have been composed "ganz ausdrücklich zur dialektischen Uebung," ib. s. 96, 2, p. 128.]
[Side-note: Force of the negative case in the Parmenidês. Difficulties about participation of sensible objects in the world of Ideas.]
The negative case, made out in the Parmenidês against the theory of Ideas, is indeed most powerful. The hypothesis of the Ideal World is unequivocally affirmed by Sokrates, with its four principal characteristics. 1. Complete essential separation from the world of sense. 2. Absolute self-existence. 3. Plurality of constituent items, several contrary to each other. 4. Unchangeable sameness and unity of each and all of them.--Here we have full satisfaction given to the Platonic sentiment, which often delights in soaring above the world of sense, and sometimes (see Phædon) in heaping contemptuous metaphors upon it. But unfortunately Sokrates cannot disengage himself from this world of sense: he is obliged to maintain that it partakes of, or is determined by, these extra-sensible Forms or Ideas. Here commence the series of difficulties and contradictions brought out by the Elenchus of Parmenides. Are all sensible objects, even such as are vulgar, repulsive, and contemptible, represented in this higher world? The Platonic sentiment shrinks from the admission: the Platonic sense of analogy hesitates to deny it. Then again, how can both assertions be true--first that the two worlds are essentially separate, next, that the one participates in, and derives its essence from, the other? How (to use Aristotelian language[28]) can the essence be separated from that of which it is the essence? How can the Form, essentially One, belong at once to a multitude of particulars?