Aquinas on the components of production

On a number of occasions throughout his various works, Aquinas defends the filioque (namely, the claim that the Holy Spirit is produced by two persons, the Father and the Son). At one point (SCG 4.24, n. 11), he says this:

'If the Holy Spirit were distinct from the Son, then they'd have to be produced by distinct productions or processions. Two productions, however, can only be distinguished by their principles, terms, or subjects.'

Never mind the first sentence. What interests me is the second sentence, for I think there's a nice bit of metaphysics here. I gather that Aquinas thinks the following three components are involved in any production:

(a) a principle,
(b) a formal term, and
(c) some receptive material (which Aquinas calls the 'subject').

Think of production as a process whereby some material gets fashioned into a product, much like how a lump of clay gets fashioned into a statue. Here, (a) the 'principle' is the source of the production, and in this sense it's the starting point of the whole process; (b) the 'formal term' is the final form the product takes, and so in this sense it's the end point of the whole process; and (c) the 'receptive material' is the stuff that gets fashioned into the final product along the way.

Of course, that's a rough way of putting it, so let's discuss each of these components in a little more detail. I'll start with the last item on the list and work my way backwards.

First, then, is the last on the list: the (c) 'receptive material'. We think of 'material' as stuff like wood, clay, or iron, but for Aquinas the meaning is a bit wider. Something deserves the label 'material' only if it has the capacity (in medieval-speak: a 'passive power') to be acted upon in some way. Aquinas calls it the 'subject' because it receives the activity of the producer. So, for example, a lump of clay has the capacity to be shaped into statues, vases, and the like, so clay is 'material' in this sense. But Socrates can be sunburnt, so he is like 'receptive material' for the sun's activity too. For Aquinas, the term 'receptive material' extends to quite to a few objects in the material world.

Further, the receptive material has to be the right kind of stuff, where 'the right kind of stuff' is anything that has the capacity to be fashioned into the particular kind of product in question. Materials have certain kinds of capacities ('passive powers'), but not others, so not all materials can be made into just any old product. Clay makes for great statues, but horrible nails. Organic tissue, on the other hand, makes for great animal bodies, but horrible statues.

Also, the receptive material has to be distinct from whatever product it's fashioned into. The very same lump of clay can become a statue, then a vase, and so it's clearly not the very same thing as the statue or the vase. If it were the same as the statue, it'd be destroyed when the statue is, but that's obviously not the case. I can smash a clay statue, but I'm still left with a lump of clay, even though the statue is no more.

As for (b) the 'formal term', different scholastic authors define this in different ways (Ockham, in particular, provides a distinctive definition in Ord. 1.5.3). But for Aquinas, it's the final form of the product. The 'formal term' is called the end point (terminus) of a production because it's the final form the product takes. When I sculpt a statue, my lump of clay takes on a succession of different shapes, but eventually I get to the one I'm after. The 'formal term' is that final shape that I finally get to, and that's why it's the 'end point' of a production.

(Sometimes a lump of matter doesn't go through a series of intermediate forms. Instead, it's immediately turned into the product in question. Living organisms are generated this way: a lump of organic tissue immediately becomes the organism in question as soon as it gets the organism's form. But even in cases like this, the product's form is the 'end point' of the production.)

As for (a), the term 'principle' has a broad meaning in scholastic writings, and it basically means 'source'. Of course, there are lots of way for one thing to be the 'source' of another, so there are lots of different kinds of principles. So what kind of principle does Aquinas have in mind when he talks about the 'principle' here?

I think there are two candidates here. First, a cause is one kind of principle. (Here I mean an 'efficient cause'. Aquinas also calls the 'formal' and 'material' causes 'principles', but those don't seem to be good candidates for what Aquinas is talking about here, so I'm only looking at the 'efficient cause', i.e., whatever acts to bring about an effect.) If we take 'principle' in this sense, then the 'principle' (efficient cause) of a production is the producer – i.e., the thing that actually does the producing.

But another kind of principle is a power source (or what I call a 'power-pack'). A power-pack, in this context, is some constituent or 'metaphysical part' of a producer that provides it with the power to produce the product in question. The idea here is that certain things have certain power-packs, and those power-packs give them certain powers. Consequently, something can only produce a particular kind of product if it has the right kind of power-pack.

On many an occasion, scholastic authors use the term 'principle' to refer to a 'power-pack' (see especially distinction 7 of the Sentences Commentaries), and so I suppose it's possible that Aquinas has the 'power-pack' in mind here when he talks about the 'principle' of a production.

So which is it? Does 'principle' mean 'producer' or 'power-pack'? I think that Aquinas must mean 'producer' here. I have two reasons for saying this. First, when some later authors present Aquinas's argument (and I'm thinking of Henry of Harclay in his Ord. Quest. 6), they just use the term 'producer' instead of 'principle'. Now, later authors often misconstrue Aquinas if it suits their purposes, but this particular reading is perfectly sensible, so I see no reason to doubt it.

Second, Aquinas's argument simply wouldn't work unless he meant 'producer'. He goes on to argue that we can only distinguish the Son and Spirit by (a) their principles, and from this, Aquinas concludes that the Son and Spirit must have different producers (the Son comes from one producer, and the Spirit comes from two producers). This wouldn't work if Aquinas didn't mean 'producer'. If he meant 'power-pack', he could only conclude that the Son and Spirit come from different 'power-packs', not different 'producers'.

A production, then, is a process whereby a producer (the 'principle') takes a lump of 'receptive material', and fashions into a product by giving it a particular form (the 'formal term'). This provides an abstract account for many different kinds of production: a statue is produced when a lump of clay is given a statue shape; a human being is produced when a lump of organic tissue is given a human form; 'tan Socrates' is produced when Socrates is given a tan color; and so on.