“Regarding what the Platonists say concerning the First Principle of things their opinion is most true and consonant with the Christian faith.” This quote is drawn from the opening of St. Thomas Aquinas’ excellent commentary on Dionysius’ Divine Names. In this commentary, Thomas frequently employs Platonic ways of speaking and he even approves of certain Platonic principles such as the Procline view of causality (omne agens agit sibi simile), unparticipated exemplar causes in God’s Mind, the principle that more perfect causes cause more effects, and many others. At one point Thomas equates “the secondary gods” of Platonism with angels. “What the Platonists called secondary gods we call angels.” Needless to say, there is a large overlap between Thomas’ work here and the Platonic tradition. And not only here! For many of the principles he outlines here, he employs in writings under his own name. In the Summa, for instance, Thomas appeals to Platonic accounts of causality to explain how predication of God is possible, while acknowledging God’s unparticipated and unparticipatable nature (see especially Q13: On the Names of God).
Suffice it to say that Thomas would not have considered himself a Platonist, insofar as he thought that position entailed belief in separable substances of common natures, such as Man in Himself, for instance. I wrote in one of previous posts that I think this is a misunderstanding, for Plato says in the seventh letter and the Timaeus that the order of being seems to be different from our modes of thinking and speaking about it. (The standard critique I here from Aristotelians and Thomists is that Plato confused the modus intelligendi with the modus essendi). Form exist prior to number, and prior to one and many, which is the reason why they can ground any particular material instantiation or universal consideration. In Thomas’ and Avicenna’s language, they are indifferent to the one and the many.
Yet, I think that the principles outlined above, along with the manifold influences of Augustine, Boethius, and the Liber de Causis, warrant Thomas’ inclusion in a ‘big tent Platonism.’ But one shouldn’t put too much stock in ‘-isms.’ My reason for making the above pitch was to suggest that, for St. Thomas, it seems like one can read Plato and Aristotle along Neo-Platonic lines. Regarding the material world, that is, Aristotle can be one’s authority, so long as one subordinates Aristotelian philosophy of nature to Platonic theological principles regarding the First Cause.