Cratylus, an Athenian, was contemporary with Socrates but was probably considerably younger. He was, according to Aristotle, a follower of the doctrines of Heraclitus, and Plato, in his youth, was closely associated with him. Aristotle implies that this was before he came under Socrates' influence, although later sources put the influence of Cratylus upon Plato after the death of Socrates.
Cratylus took as his starting point the doctrine of the flux of phenomena (here assumed to have been a genuine doctrine of Heraclitus, despite G. S. Kirk's objections), and he capped Heraclitus's saying that one cannot step twice into the same river by adding "nor once either." His reason clearly was his contention that the river is changing even as you step into it. He ended by coming to the view that one ought not to say anything, but only move the finger, since no true statement can be made about a thing that is always changing. According to Aristotle, upon whose evidence the above account rests, Plato took from Cratylus the belief, which he maintained even in later years, that all sensible things are always in a state of flux and that there is no knowledge about them.
Plato in the Cratylus attributes to him the doctrine that everything has a right name of its own, fixed by nature, and somehow or other this one right name will point to the nature of the thing named.
At an early stage it became clear to modern critics that the contention that there is a right name that indicates the true nature of a thing is apparently inconsistent with the doctrine of a Heraclitean flux in phenomena, since this flux would prevent a thing from having an abiding nature. Attempts to explain this contradiction in Cratylus's position have been numerous. Frequently it has been supposed that Cratylus either did not have a doctrine of words at all or else did not believe in the flux doctrine.
All such explanations seem misguided. Aristotle makes it clear that the final step—the refusal to use words—came after a previous period when Cratylus was already a Heraclitean. The implications of Plato's account are also clear; Cratylus at the time of the dialogue had long been interested in the doctrines of Heraclitus, and he also held the theory of words attributed to him. It might be that he failed to realize the inconsistency at the stage represented by the dialogue, and, when the inconsistency became clear, subsequently proposed to abandon speech. More probably, at the time of the dialogue he inclined to the view to which he is clearly attracted when Socrates mentions it, namely, that words themselves in some sense flow, and so point to the flowing nature of the objects to which they refer (Cratylus, 437d).
Testimonia in Diels-Kranz, Fragmente der Vorsokratiker, Vol. II, 10th ed. (Berlin: Weidmann, 1961). See also V. Goldschmidt, Essai sur le Cratyle (Paris: H. Champion, 1940); G. S. Kirk, "The Problem of Cratylus," in American Journal of Philology 72 (1951): 225–253; D. J. Allan, "The Problem of Cratylus," ibid., 75 (1954): 271–287; H. Cherniss, "Aristotle, Metaphysics 987a32–b7," ibid., 76 (1955): 184–186.
G. B. Kerferd (1967)