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On the Third Attempted Definition of Knowledge, Theaetetus 201c–210b

  • May Yoh (a1)


There seem to be as many interpretations of the Theaetetus (Tht.) 201c–210b as there are scholars who care to interpret it. This, of course, is not surprising. As Cherniss well puts it,

the fascinating and perplexing history of Platonic interpretation…has been so largely a series of insistently charitable efforts on the part of Western philosophers and their acolytes, each to baptise Plato in his particular faith — having shriven him first, of course, by interpreting the heresies out of his works.



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1 “The Relation of the Timaeus to Plato's Later Dialogues” in Allen, R. E. ed. Studies in Plato's Metaphysics (henceforth referred to as Allen), London, 1965, p. 347.

2 H. F. Cherniss: “The Philosophical Economy of the Theory of Ideas”, published one year after Cornford's, F. M.Plato's Theory of Knowledge (henceforth referred to as PTK), i.e., in 1936, now collected in Allen pp. 1 ff.; Hackforth, R.: “Platonic Forms in the Theaetetus” in The Classical Quarterly, New Series Vol. VII (1957), pp. 53 ff., and to a large extent, cf. Bluck, R. S.: “Logos and Forms in Plato: A Reply to Professor Cross”, (1956), now in Allen, pp. 33 ff.; they hold similar views to Cornford's. In A. Koyre's “The Theaetetus”, it is likewise maintained that we can draw a positive conclusion from the apparent negative result of the discussion on knowledge, one which is associated with Plato's theory of Forms; cf. Koyré, A.: Discovering Plato, (trans, by Rosenfield, L. C.), Columbia University Press, 1945, especially pp. 4551.

3 Robinson, R.: “Forms and Errors in Plato's Theaetetus” in The Philosophical Review, Vol. LIX (1950), pp. 3 ff..

4 Ibid., p. 14.

5 Ibid., p. 18.

6 Ibid., p. 15.

7 The unpublished version is extensively quoted by Hicken, W. F.: “The Character and Provenance of Socrates' ‘Dream’ in the Theaetetus”, in Phronesis, Vol. 3 (1958), pp. 126 ff.; also quoted by Cross, R. C.: “Logos and Forms in Plato”, in Allen, pp. 13 ff.; and cf. Meyerhoff, H.: “Socrates' ‘Dream’ in the Theaetetus”, in The Classical Quarterly, New Series Vol. VIII (1958). pp. 131 ff.. The later version of Ryle's, G. paper is: “Letters and Syllables in Plato”, in The Philosophical Review, Vol. LXIX (1960), pp. 431 ff.. In his more recent publications Ryle also maintains that Plato is “at least detached from his old Theory of Forms” in the Theaetetus, which is concerned rather with semitechnical, grammatical and semantic questions about the elements and the compositions of truths and falsehoods, cf. his book Plato's Progress, Cambridge University Press, 1966, especially pp. 1417 and pp. 275–280; and his article on Plato in The Encyclopedia of Philosophy ed. by Edwards, P., , Macmillan. 1967, Vol. 6, pp. 314 ff., especially cf. pp. 319–329.

8 Now in Allen, pp. 97 ff..

9 The sense-data view, for instance, is attributed by H. Meyerhoff to Plato, in “Socrates' ‘Dream’ in the Theaetetus” in The Classical Quarterly, New series vol. VIII (1958), pp. 131 ff. According to Meyerhoff, the letters in the “Dream” stand for sense-data of which we are immediately aware; but of which we can have no knowledge for two reasons: sense-data have no logos since logos is a combination of names, and also, these sense-data cannot be “stated”. The refutation of the “Dream” shows the difficulty of which Plato is aware, namely, knowledge is not based on sense-data. On this interpretation, the “Dream” is a continuation of the first attempted definition of knowledge as perception. Although it is true that Plato refutes the view that knowledge is based on perception, or indeed, sense-data, I do not think that sense-data are meant to be what letters in the “Dream” stand for. If the “Dream” is connected with what follows it, as Meyerhoff holds, then the individual things and persons (which obviously are not sense-data), mentioned in 207a (e.g. wheels, axles, etc.), and 209b (e.g. Theaetetus and Socrates) respectively, should bear counter-evidence to the interpretation that letters stand for sense-data. The fact seems to be that Plato does not mean by letters and syllabes anything specific. Meyerhoff's interpretation of logos merely as a combination of names and his view that knowledge has to be statable resemble Ryle's views which will be discussed in the text of the paper later.

10 I am aware of G.E.L. Owen's view that the Timaeus is designed by Plato as the crowning work of the Republic group, and hence, is composed before the group of the so-called critical dialogues, of which the Theaetetus is one: cf. Owen, G.E.L.: “The Place of the Timaeus in Plato's Dialogues” in The Classical Quarterly, New series Vol. III (1953), pp. 79 ff., now collected in Allen, pp. 313 ff. On the dating of the Timaeus, Ryle, of course, holds the same view as Owen's, cf. his Plato's Progress and the Encyclopedia article mentioned above. But I consider that Cherniss has sufficiently refuted Owen, and believe that the Timaeus belongs to the last group of Plato's writings: cf. Cherniss, H. F.: “The Relation of the Timaeus to Plato's later Dialogues”, in Allen, pp. 339 ff.. In any case, my criticism of Ryle and Robinson will also utilise certain passages in the Cratylus, which even Ryle in his recent publications thinks belongs to the same group as Theaeteus, cf. Plato's Progress, pp. 272–275 and Encyclopedia of Philosophy, vol. 6, p. 320. Thus, even if some may not accept Cherniss's refutation of the minority view on the dating of the Timaeus, my criticism of Ryle and Robinson, in so far as it utilises the Cratylus, is independent of the problem of the dating of the Timaeus, and therefore, should be considered separately.

11 The Philosophical Review, Vol. LIX (1950), p. 19.

12 Here again, I regard the Timaeus as being later than the Theaetetus; cf. note 10 above.

13 cf. The Philosophical Review, Vol. LIX (1950), p. 15.

14 cf. Cratylus 388b ff., and what follows in the text of the present paper.

15 Plato's use of the letters-and-syllables analogy in the later dialogues would also be supporting evidence for my view here.

16 Hicken, W.: “The Character and Provenance of Socrates' ‘Dream’ in the Theaetetus” in Phronesis, Vol. 3 (1958). cf. p. 131.

17 Cornford, F. M.: PTK, p. 155.

18 cf. Sophist, 259e.

19 The Republic, 596a ff..

20 cf. Cherniss, H. F.: “The Philosophical Economy of the Theory of Ideas” in Allen, pp. 1 ff..

21 For a very similar statement of the point, cf. Chapter 8 of Book I of Aristotle's Posterior Analytics, especially Sir David Ross' explanation on p. 533 of his Aristotle's Prior and Posterior Analytics, Oxford at the Clarendon Press, 1949.

22 My speculation partly arose from reading Sir Karl Popper's “On the Sources of Knowledge and of Ignorance” (especially section VII). in his Conjectures and Refutations, Tondon, 1963, pp. 3 ff.. Popher himself, however, has conjectured that there may have been an earlier lost edition of the Theaetetus which can be dated as earlier than the Republic, although the existing revised edition possibly may be placed even after the Sophist, cf. Vol. 1, pp. 321322, of The Open Society and Its Enemies, fifth edition, London, 1966.

23 Notably by Lee, E. N.: “On the Metaphysics of the Image in Plato's Timaeus” in The Monist, Vol. 50 (1966), pp. 341 ff..

On the Third Attempted Definition of Knowledge, Theaetetus 201c–210b

  • May Yoh (a1)


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