Today I am thinking about some of Aristotle's objections to the Platonic theory of Forms, and the response to these objections that is given by the late Neoplatonist, Syrianus. What is notable about Syrianus' response is that he seems to employ Aristotle's own concept of focal predication to refute the latter's objections. While Syrianus' refutation of Aristotle is quite polemical and heavy-handed at times, Syrianus clearly has a great deal of respect for Aristotle. One might describe his dialogue with Aristotle as an attempt to bring Aristotle back into line with what he views as the essential tradition of Platonism. His correction of Aristotle is thus not absolute; rather, by his correction of Aristotle he attempts to show that Platonism is indeed compatible with the most fundamental principles of Aristotelian philosophy, despite Aristotle's own failure to recognize this compatibility.
Aristotle's arguments are presented in a few places. In Book A chapter 9 of Metaphysics, he summarizes some of his most important arguments; and Book M contains a parallel rewritten version of these same arguments. Aristotle's arguments are founded on the presupposition of a dichotomy of absolute univocity versus absolute equivocity – i.e. synonymy versus homonymy – between the Forms and their instances. To recall the theory of Forms, Plato posits the Forms as the exemplars of their particular instances, such that this individual man is only said to be a man by virtue of the Form of Man itself; or the beautiful is said to be beautiful only in virtue of the Beautiful itself. Aristotle is presupposing that the term "beautiful" is said either univocally or equivocally of both the Form and its individual instance, or of Beauty Itself and of this beautiful thing. On either assumption, or univocity or equivocity, Aristotle supposedly discovers that Plato's theory must necessarily fail.
On the presupposition that Forms and particulars are synonymous or univocal, Aristotle cannot see how Plato really succeeds in maintaining any meaningful understanding of the transcendent causality of Form. For example, the Form turns out to be just another particular, perhaps differing in degree of perfection, but still needing another Form to explain it, and so on ad infinitum – the famous “Third Man” argument. On the presupposition that Forms and particulars are homonymous or equivocal, there would seem to be no real community between Forms and their particulars, but only a common name, and perhaps a completely accidental similitude. To describe Forms as “paradigms” in which particulars “participate” is only to utter “empty talk and poetic metaphors.” Nor, however, will Aristotle admit of some middle way between synonymy and homonymy - e.g. a partial overlap of definition, with the added qualifications that Forms are eternal or intelligible, while particulars are temporal and sensible. For it would seem to be completely arbitrary how these properties are added to the definitions of each: i.e. the Form of Circle and a particular circle may share the same definition; but a definition has parts – e.g. a plane figure comprehended by a single line that is equidistant at all points from a single point not on that line, namely the center. To which part of this definition is the attribute “intelligible” or “sensible” to be added, or to the whole? In these, and other related ways, Aristotle seeks to disprove the Platonic position.
In response, Syrianus shows that there is a legitimate third option between pure univocity and pure equivocity; and this he shows by applying Aristotle's own device from Book Γ, the pros hen (πρός ἔν) manner of predication. Syrianus approves of Aristotle's use of this technique, in his own commentary on Book Γ, and he appears to reapply this very same reasoning, in his commentary on Book M, in response to Aristotle's own objections against the Forms of Plato in book M: Forms are neither synonymous nor straightforwardly homonymous with their particulars; rather, they are analogous (to use the term which would be employed by the medievals - not necessarily Aristotle's term here; this is an interesting and controverted issue in itself). That is to say, particulars are named homonymously with this qualification, that they nonetheless bear a common focal reference to their Form, which is primary and paradigmatic. Just as substance is the primary being with respect to its accidents, and communicates its being to them, so to speak, so is Form the primary being with respect to its particulars, and it communicates its being to them as their universal paradigmatic cause. Accidents are called beings only with reference to substance - and they are beings only by participation in the being of substance. Likewise, all sensible particulars are what they are only with reference to, and by participation in, their exemplar Forms.
Of course, Syrianus does not solve all questions with this response. Nonetheless, the specific objections of Aristotle, insofar as they rely on the dichotomy of synonymy versus strict homonymy (and an incomplete consideration of some middle ground) - and especially the "Third Man" argument - are at least rendered less convincing. But questions remain concerning how exactly the forms cause anything, as they are meant to; and, moreover, just what kind of things they actually are.