I confess that I'm having a hard time understanding what Gerson means by a 'harmony' between Aristotle and Plato. I'll share some of my problems here with you.
I've been looking at Gerson's chapter on ethics and the good. One might think at first glance that here no harmony is possible. Aristotle presents a dozen objections to a Form of the Good; whereas, if Plato can account of goodness at all, it would be through appeal to a Form. Again, Aristotle thinks that, even if such a Form existed, knowledge of it would be irrelevant to human action; but Plato takes knowledge of the Good Itself to be essential to human goodness. Seems like an irreconcilable difference, no?
To 'reconcile' them, Gerson first points to the relatively superficial similarity, that both Plato and Aristotle think that there is a unique highest good:
We must be careful here to realize that in rejecting a superordinate Form of the Good, whether or not it is identical with that which is called 'the One', Aristotle is evidently not rejecting a unique good--namely, God--which is, as we have seen, unequivocally called 'the good' in the sense of 'the on account of which' or final cause (260-1).This remark, of course, would 'harmonize' Aristotle not only with Plato but also with all theists, most idealists, and hundreds of other assorted philosophers. That is, it yields so far an empty harmony.
Gerson next writes the following.--And observe how he seems to shift seamlessly from what Neoplatonists think to what (it seems) he himself thinks. There are numerous passages like this in the book, which easily give rise to the idea that Gerson is not simply engaging in historical investigations but also offering an argument in his own voice:
So, it would not be unfair for Neoplatonists to claim that Aristotle recognizes a unique good at which everything aims or is oriented, though, in identifying it with intellect, he does not fully recognize its nature. His rejection of the Form (or the Idea) of the Good is, accordingly, owing in part to the mistaken belief that there could not be anything transcending intellect and so there could not be a truly 'universal good.' Indeed, his identifying the good with the thinking of God seems to make the good unacceptably limited, since strictly speaking it precludes the goods belonging to anything that does not think (261).Is Gerson saying that the Neoplatonists regarded this as a 'mistaken belief', or that it really is a mistaken belief? The word 'Indeed', and Gerson's offering of an additional objection in the very next line, make it seem as if Gerson himself endorses these objections.
But, again, what sort of a 'harmony' would this imply? If philosopher A becomes harmonized with philosopher B, when A objects to B on grounds that miss the point (or, really, on grounds that seem like they miss the point to a follower of B), then, for instance, Bertrand Russell now becomes harmonized with every philosopher in the history of the West!
I suppose one would need to claim, more strongly, that A's views are such that they would bind him to accept the views of B, if he really did understand B. But Gerson nowhere argues that Aristotle, on Aristotelian grounds, would be bound to accept the Neoplatonic view of the 'One', or would be obliged to accept that such an entity helps to account for ordinary instances of goodness. (Gerson elsewhere cites Plotinus as arguing that 'thought thinking itself' could not be a suitable first cause, because a truly first cause must lack any complexity and be 'the One', pp. 206-7. But it seems enough for Aristotle if the first cause lacks any potentiality or coroporeality.)
Gerson next remarks, as regards Aristotle's objections in NE I.6 (and EE I.8) against the Form of the Good, that these objections:
...do not clearly indicate that the Form of the Good is understood by Aristotle to have the superordinate status it has in Republic [sc. as beyond ou)si/a]. As we shall see, the objection to this Form could just as well serve as objections to other Forms, mutatis mutandis. So, insofar as the objections assume that the Form of the Good is an ou)si/a, rather than that which is "not itself ou)si/a," as Republic specifically states, they do not really touch Plato's position, as understood by the Neoplatonists (261).A small point: many of the objections in NE I.6 do not "just as well serve as objections to other Forms", as they hinge on the distinct behavior of 'good' as a 'transcendental' predicate.
Also: in various places Plato does speak as though he thinks there is a Form of Good which is an ou)si/a on a par with all the other Forms (e.g. ei0 me\n e1stin a4 qrulou~men a)ei/, kalo&n te/ ti kai\ a)gaqo_n kai\ pa~sa h( toiau&th ou)si/a, Phaedo 76d), so what Gerson says here applies to one version of Platonism, perhaps not the best or most representative version.
But, most importantly, it does not help one iota, by way of harmony, to urge as Gerson does that "Platonism regards the Good as beyond ou)si/a", if the view that "Good is beyond ou)si/a" is even more problematic, and seems even less promising as an account of our use of the word "good", than the view that the Good is an ou)si/a!
Look: if Aristotle on philosophical grounds shows little patience for the view that the Good is a Form, he will have even less patience with the view that it is a "One" beyond all ou)si/a.
Hence it is a fallacy--at least as regards any sort of harmonization--when Gerson writes:
...it should be pointed out that much of what Aristotle says [in NE I.6] loses its force if the Form of the Good is superordinate and hence not an ou)si/a. For it is only an ou)si/a that is a 'one-over-many' and so conceivably predicable univocally of many (262).I wonder if what Gerson really means has little to do with 'harmony'. I wonder if his meaning is no more than that a dedicated Neoplatonist will not regard Aristotle's objections as a reason to change and adopt Aristotelianism. This would be unremarkable; it would simply mean that Neoplatonism has an internal coherence, and resources within, comparable to most serious philosophical systems. But it does nothing to establish a harmony between Aristotle and Plato.