1. This view has been defended by several influential revisionists in the past. For instance, according to Gilbert Ryle, Plato in Parmenides “overtly” demonstrates the “untenability of the very principles” of his philosophy. For this reason, in his later dialogues, he only “attends the theory of [Forms] on occasions, but he does so in a dispassionate and critical way.” Ryle adds that, beginning with Parmenides, Plato had discovered “that certain important philosophic truths and methods were to be credited not to Socrates but to the Eleatics. [Henceforth,] Zeno is the teacher and not Socrates.” Ryle does not really bother to demonstrate these fantastic claims. His evidence is mainly that Taylor contradicts himself on this matter, and Plato, in Theaetetus and Sophist, “goes out of his way to express his admiration for [Parmenides].” Gilbert Ryle, “Plato’s Parmenides,” in Studies in Plato’s Metaphysics, ed. Reginald E. Allen, 97–147 (London: Routledge and Kegan Paul, 1965), 133–34, 98.
2. Similarly, Richard Robinson claims that, beginning with Parmenides, Plato still “thought he believed” in the theory of Forms, “though in his active inquiries he was in fact beyond it, and [the theory of Forms] functioned as theory to be criticized instead of as the rock of salvation that it had been in in his middle period.” Without any evidence (except that Cornford is wrong), Robinson asserts the following: “It is the fact that in Parmenides, Theaetetus, Sophist, Statesman and Philebus, the only obvious references to the theory of Forms as found in the middle dialogues are the acute objections offered to it in the Parmenides and the Sophist.” Richard Robinson, “Forms and Error in Plato’s Theaetetus,” Philosophical Review 59, no. 1 (1950): 18–19.
3. According to Gwilym E. L. Owen, “The [middle-period] project was abandoned from dissatisfaction with certain basic theories.” In Parmenides and Theaetetus, which are presumably the first self-critical dialogues, Plato makes a “fresh start on problems still unsolved.” This revisionist view came under serious attack—on the ground that a late dialogue, Timaeus, retains the middle-period TF pretty much intact. Owen responded by revising the chronology of Plato’s dialogues. Timaeus, he claims in an influential article, belongs to “the Republic group”—that is, to the pic-Parmenides, middle-period dialogues. Gwilym E. L. Owen, “The Place of Timaeusin Plato’s Dialogues,” in Studies in Plato’s Metaphysics, ed. Reginald E. Allen, 313–38 (London: Routledge and Kegan Paul, 1965), 316. However, Harold F. Cherniss has convincingly argued that Timaeus is a late dialogue.
4. Harold F. Cherniss, “The Relation of Timaeus to Plato’s Later Dialogues,” in Studies in Plato’s Metaphysics, ed. Reginald E. Allen, 339–78 (London: Routledge and Kegan Paul, 1965).
5. To his credit, Sayre offers one of the most substantial defenses of the turning-point view. By actually examining Plato’s late dialogues, Sayre argues that the TF proposed in Sophist, and the other late dialogues, “differs in … fundamental respects from the theory” found in Plato’s “middle dialogues.” In the earlier dialogues, “Forms are absolute, both in the sense of being themselves incomposite and in the sense of not depending for what they are upon other things. This character of the Forms is severely compromised as early as the Sophist, where Forms are seen to combine with other Forms, and hence to depend on each other for being what they are.” Kenneth M. Sayre, Plato’s Late Ontology: A Riddle Resolved (Las Vegas, NV: Parmenides, 2005), 183–84. As we will see later in this chapter, what Sayre says here cannot be substantiated. However, he thinks Plato more fully implements the Pythagorean program, which he allegedly develops in Parmenides, in Philebus, and not in Sophist. As Turnbull points out, Sayre’s reading of Parmenides is “largely anticipatory of his interpretation of the Philebus.” Turnbull thinks Sayre “correctly … takes the Philebus to be a clear declaration of Plato’s Pythagoreanism.” Robert G. Turnbull, The Parmenides and Plato’s Late Philosophy (Toronto: Toronto University Press, 1998), 194.