Self-predication in Plato: The 'formal' explanation
Plato often treats Forms as paradigm cases of the Forms they are. So the Form F-ness is an F thing and perfectly so. If Forms are understood as universals, then just as F-ness is predicated of F particulars, so too F-ness is predicated of itself (i.e., the Form self-predicates or has the property it is). In the case of some Forms, this is a desirable outcome. All Forms necessarily are one, and as such, Oneness necessarily partakes of itself So too, the Form of Rest should itself be a non-changing thing as all Forms are necessarily immutable.
Yet if Plato intends all Forms to self-predicate then the following types of problems result: (1) metaphysical absurdities (e.g. the Form Man must be a literal man, and hence alive); (2) immediate inconsistencies with Platonic commitments concerning Forms (e.g. Change must change rather than being immutable); (3) an inconsistent view of Forms as both universals and perfect particulars.
To resolve these problems I proceed in the following way. After examining the issue of self-predication in more detail, I explore the traditional analyses of self-predication and argue that each suffers both substantive and methodological shortcomings.
Next, I discuss Robert Heinaman's promising methodology for resolving this issue, namely, generating criteria of adequacy based on key evidence related to self-predication. After demonstrating that Heinaman's criteria are unjustified, I supplant his criteria with four of my own. I then generate an analysis of self-predication that meets these criteria, and which portrays Plato's self-predicative commitments in a consistent manner.
Ultimately I analyze self-predication in terms of formal causation, Plato's view that the Form F-ness makes F things F through its presence. The Form F-ness is an F thing precisely because it formally causes other things to be F. I defend this analysis of self-predication both by showing that it is the only account of this phenomenon consistent with the criteria of adequacy, and by providing independent evidence that Plato views formal causation.