University of Dayton
In the final argument of the first part of the Pannenides, Plato raises an objection to the separate existence of Forms. This argument, which I shall call the "Two-Worlds Argument"1 (TWA), takes up more space than any of the other arguments against the Theory of Forms (TF), occupying almost two Stephanos pages (133a-134e). It is, moreover, the only argument in the series about which Plato permits Parmenides to offer an editorial comment, the comment being that the argument is the most serious objection to the TF, but that it can be answered. In spite of this assessment, which I believe represents Plato's own view, the TWA has not received the attention of its more celebrated relative, the Third Man Argument (TMA); and such attention as it has received has not been favorable. Thus, the TWA has not been taken by scholars to have the importance Plato ascribes to it, and has not been treated as a turning point in Plato's thought.
The scholars who disparage the TWA are wrong, however. In spite of some problems involving the correct formulation of the argument, problems which have given rise to the notion that the argument can be given a "quick fix" resolution, the TWA is in fact a very serious objection to the TF, and Plato's response to it in the late dialogues does take the form of the long and laborious argument Parmenides says is required (133b-c). In this paper I shall attempt to analyze the impact of the argument on the TF in such a way that Plato's judgment of its force is vindicated. First, I shall state the argument itself. Then, I shall argue that a formulation of it that has recently gained some acceptance is inadequate, and provide a valid formulation of the argument. Third, I shall argue that a well-known response to the argument fails to bring out its true force, and attempt to do so myself. Fourth, I shall indicate briefly what I take Plato's actual response to the argument to have been.
Prior, W. J. (1982). The Two-Worlds Argument and the Development of Plato’s Metaphysics. The University of Dayton Review 16, 35-42.