Third man argument

The aim of this paper is to discuss one possible interpretation of Plato's Third Man argument. Plato's theory has been outlined by focusing on those premises usually taken as important for the formulation of the argument. The argument is then brought into connection with the theory of types although it is not assumed that self-predictional sentences in Plato's theory have the same role as in Russell's paradox. Employing the notion of "well-defined class", it is pointed out in what respect the argumentation is invalid, i.e. why Plato's theory of ideas needs not to lead to an infinite regress or a paradox of self-predication.