In the last pages of the Theaetetus Socrates is made to present four versions of a final attempt to define knowledge, as true opinion accompanied by logos, and to reject them all; yet in earlier dialogues ‘ability to give account’, λόγον ἔχειν or λόγον διδόναι δύναδθαι is closely associated with knowledge, not always, or not necessarily, knowledge of Forms, and in the Republic it is said to be the essential mark of the dialectician. These facts are exceedingly hard to interpret. In recent years the passage has been read as an indirect defence of the earlier theory of Forms, as the statement of a problem answered in the Sophist by a revision of that theory and as a piece of radical self-criticism. No one of these interpretations seems tome without difficulty, and in this article I shall attempt to argue for yet another solution which owes something to all three.
Professor Cornford, pressing the fact that Socrates draws all his illustrations from the world of concrete things, believes that Plato intended by criticism of the different versions to point the way to an old and invulnerable sense of λόγον διδόναι, which implies that the proper objects of knowledge are Forms. This is the statement or understanding of grounds for judgments which in the Meno is said to turn true opinion into knowledge. A rather similar line has been taken by Professor Cherniss. Professor Stenzel thinks that the earlier theory of Forms is vulnerable to Socrates' criticism of what I call ‘the first version’, the ‘dream’, but he believes that all three of the later versions ‘recover their meaning’ when the problem of definition has been solved in the Sophist with the help of the method of diaeresis; and so restated they can be shown to apply to particulars as well as to Forms.