Plato's theory of the forms?

[anvi]

No.  I think Aristotle dealt a powerful objection to Plato's forms, not through his use of Parmenides' "third-man" argument but through his critique of the notion of "sharing" in the first book of the Metaphysics.  There is something to the third-man argument too, as it calls into question the idea that the Forms are kinds of self-predicated genus, and such self-predication is uninformative.  But the real problem with Plato's forms is that nothing is really added to our understanding of natural things by saying they "copy" a transcendent form, since one thing can copy or share a likeness with something that does not even exist.  Instead, when we do speak of things that share features with one another, that commonality is exhibited in their instantiations (in rebos), and saying they come from some other realm of forms is superfluous. 

It's interesting that the notion of Platonic forms seems first to have arisen in connection with Plato's theory of values--his idea that certain moral universals like courage, piety and so on had to exist.  He gets pushed toward an overarching naturalistic theory as the Dialogues progress, but even in the Parmenides, he can't really extract himself from the problems and implications of the extended theory.