The following is an excerpt from a letter I wrote to a friend recently in discussion of Aquinas’s view of Platonic forms. It is well known that Aquinas assimilated Aristotelian metaphysics into Christianity, often by extending or clarifying the Platonic metaphysics which had sufficed to his day, largely from Augustine, who, as Aquinas says, was “imbued with the doctrines of the Platonists.” However, as I mean to demonstrate below, Aquinas did not do so by abrogating the Platonic “form” (a move that was subsequently made by Enlightenment moderns) but rather by assimilating them, I think more orthodoxly, into Christian doctrine.

I think the work you’re doing with tracing the philosophical origins of modernism back before the traditional period markers is going to be a real vital contribution. I totally agree that “the Enlightenment is the extension of late medieval nominalism,” and I love that you’re roasting the nominalists. Down with Ockham!

But I do wish to save Aquinas from the flames of your roasting. I would draw the line of blame between Aquinas and Ockham; if Ockham and the other Nominalists did “follow him,” it was not as protégés, but as robbers following someone down a dark alley.

I read one of your main lines of argument to be, essentially, that Aquinas deserves at least some blame because his philosophy lent itself, or inherently disposed itself (whether by his express intention or by culpable negligence) to the abuses of the nominalists, because it denied the real existence of Forms. You say that Aquinas “denies the existence of the Ideal Form of which individual material entities share an essence. The form/category is only something we infer from similarities of particular objects—not something actually there.” I agree that Aquinas would have taken an inadvertent first step toward modernism if he had denied the existence of forms (he would have been a sort of materialist, eh?); however, I argue that he did not.

In the Summa, I:15:1, Aquinas deals with “Ideas,” which is the Greek word which equates to the Latin forma. He asks whether there are ideas, and concludes that “it is necessary to suppose ideas in the divine mind,” since “in all things not generated by chance, the form must be the end of any generation whatsoever,” and, “as then the world was not made by chance, but by God acting by His intellect…there must exist in the divine mind a form to the likeness of which the world was made.” (He even goes on to say in Article 3 that “there are ideas of all things that God knows.”)

In his reply to Objection 1 he qualifies that “Aristotle (Metaph. ix) rejects the opinion of Plato, who held that ideas existed of themselves, and not in the intellect,” using this as an explanation for why “God does not understand things according to an idea existing outside Himself.” I sense that the temptation would be to point to this and say, “There. He says ideas do not exist of themselves. Therefore he doesn’t believe they are real, in an objective sense.” However, his statement that forms exist in the intellect cannot be taken to mean that they therefore do not really exist. Rather, the intellect is the part of rational beings which is capable of understanding things, and ideas exist within this dimension, within the “houses” of these parts of rational beings; but that they are relative or not real is ruled out by his claim that they exist in the intellect of God, because, if they exist in God’s mind, then they exist truly, and objectively, being independent of the intellect of any man.

So he says forms exist; they exist in the mind of God. But Aquinas might still be guilty of functionally denying them if he denied that men can know them.

But Aquinas says that men do indeed know the forms, or “eternal types,” when they know anything. In I:84:5 he says:

We must needs say that the human soul knows all things in the eternal types, since by participation of these types we know all things. For the intellectual light itself which is in us, is nothing else than a participated likeness of the uncreated light, in which are contained the eternal types. Whence it is written (Psalm 4:6-7), “Many say: Who showeth us good things?” which question the Psalmist answers, “The light of Thy countenance, O Lord, is signed upon us,” as though he were to say: By the seal of the Divine light in us, all things are made known to us.

Aquinas goes so far as to address Plato’s concept of forms, and how we ought to—indeed, how Augustine did—admit it, and yet modify it to be suitable to Christian thought:

As Augustine says (De Doctr. Christ. ii, 11): “If those who are called philosophers said by chance anything that was true and consistent with our faith, we must claim it from them as from unjust possessors. For some of the doctrines of the heathens are spurious imitations or superstitious inventions, which we must be careful to avoid when we renounce the society of the heathens.” Consequently whenever Augustine, who was imbued with the doctrines of the Platonists, found in their teaching anything consistent with faith, he adopted it: and those things which he found contrary to faith he amended. Now Plato held, as we have said above (Article 4), that the forms of things subsist of themselves apart from matter; and these he called ideas, by participation of which he said that our intellect knows all things: so that just as corporeal matter by participating the idea of a stone becomes a stone, so our intellect, by participating the same idea, has knowledge of a stone. But since it seems contrary to faith that forms of things should subsist of themselves, outside the things themselves and apart from matter, as the Platonists held, asserting that per se life or per se wisdom are creative substances, as Dionysius relates (Div. Nom. xi); therefore Augustine (QQ. 83, qu. 46), for the ideas defended by Plato, substituted the types of all creatures existing in the Divine mind, according to which types all things are made in themselves, and are known to the human soul.

Here again, we see that Aquinas accepts the existence of forms, and holds that when we know anything, it can only be by the participation of our intellect in those forms; but he corrects Plato, or rather cites Augustine’s correction, by saying that forms do not exist in themselves, for then they would be creative substances (taking the place of the Creator God), but rather they exist in the Divine mind.

What do you think? Have I missed something here, or shall we clear Aquinas of the charge?