Aquinas on the Filioque

In the last two posts, I talked about what Aquinas thinks are the essential ingredients or components of any production, and how he thinks those components allow us to distinguish two productions. As I explained, for Aquinas, every production will involve (a) a producer, (b) a 'formal term' (which is the final form the product takes), and (c) the receptive material that gets fashioned into the final product along the way. And given these, Aquinas thinks we can distinguish two productions if they differ with respect to at least one of these components.

Aquinas uses all of this, of course, to distinguish the Son from the Spirit, and so I might as well wrap this up by quickly going over that. Immediately after the quote I gave two posts back (the one from SCG 4.24, n. 11), Aquinas goes on to argue that we can only distinguish the Son and Spirit by their producers, not 'formal terms' or 'receptive material'. He reasons as follows.

First, we can't distinguish the Son and Spirit by (c) their receptive material, he says, because the Son and Spirit aren't material things, so there aren't two lumps of material there.

(Note that some scholastic authors, Henry of Ghent in particular, disagree with part of Aquinas's claim here; for Henry of Ghent, the divine essence is like a lump of quasi-material that all the persons are made from. Of course, there's just one such lump, so we couldn't distinguish the Son and Spirit based on that.)

Second, we can't distinguish the Son and Spirit by (b) their 'formal terms' either, because for Aquinas, the Son and Spirit have the very same form, namely the divine essence.

(Again, note that not all scholastic authors accept this. Henry of Ghent, again, thinks the personal properties (not the divine essence) are the forms of the persons, and those are all different.)

Third, that leaves (a) their producers. The Son and Spirit must, then, have different producers. Therefore, Aquinas concludes, the Son must be produced by one person (the Father), and the Spirit must be produced by two (the Father and Son together).

(Note also: This argument could equally conclude that the Son is produced by the Father alone, and the Spirit is produced by the Son alone. That'd amount to different producers too. But Aquinas would respond that if the Son were the sole producer of the Spirit, we might as well just call the Son 'father' and the Spirit 'son', for 'father-son' really means 'one producer-one product'. But that would be no good. The notion that 'father-son' relations only apply to 'one producer-one product' scenarios is precisely the point that Aquinas is trying to prove here, so he couldn't slip that in before he's proved it.)