Friday, December 26, 2008

Aquinas on the distinction of spirits

In the Summa Contra Gentiles, book 4, chapter 24, Aquinas provides a number of arguments for the filioque (i.e., the claim that the Spirit is produced by two divine persons, namely the Father and the Son). In one of those arguments (n. 8 in the Taurini 1961 edition), he makes the following claim:
In things where the material distinction is removed (and a material distinction cannot have any place in the divine persons), no two things are found to be distinguished unless by some opposition.
Here Aquinas is saying that when it comes to non-material things (let’s just call them spirits), the only distinction is one between opposites. That is, any two distinct spirits are opposites in some way. Let's formulate this claim like so:
(A1) For any spirits x and y, x and y are distinct iff x and y are opposites.
Right away, I’m skeptical. A1 states that all spirits are opposites, but why should we believe that? You and I are distinct, but we’re certainly not opposites. Why can’t two spirits be distinct like we are, without being opposites? The angels Gabriel and Michael are distinct, but are they opposites? If so, in what way?

To explain why spirits are always distinguished by opposition, Aquinas says the following:
Those things that have no opposition to each other can be in the same thing at the same time. Hence, no distinction can be caused by them. Whiteness and triangularity are diverse, but they’re not opposites, so they can belong to the same thing.
This requires some unpacking. There are three points here, and each needs to be separated. That way, we can more clearly see what Aquinas is actually saying here.

(a) The first point to clarify is based on the comment that whiteness and triangularity can exist together in the same thing. The assumption is that some features can simultaneously exist in the same thing, but others cannot. Some features have no disagreement and are perfectly happy to be together, but others just can’t be in the same room, so to speak. Let’s say that the former type are ‘compatible’, and the latter type are ‘incompatible’:
(A2) For any x and y, x and y are compatible iff x and y can exist simultaneously in some z.
(A3) For any x and y, x and y are incompatible iff there is no z in which x and y can exist simultaneously.
To use Aquinas’s own example, whiteness and triangularity are compatible because one and the same thing can be both white and triangular. And indeed, we see white triangles all the time, so whiteness and triangularity are clearly compatible in this way.

Incompatible things, on the other hand, aren’t like this. If I ask a group of people to take sides on capital punishment, that will break up the group: some will be for the death penalty, and others will be against it. These are incompatible viewpoints, so they have to be held by different individuals/groups.

(b) The second point to clarify is based on Aquinas’s comment that compatible features cannot be the cause of distinction. The claim here is that incompatible features can, but compatible features cannot, be the cause of distinction. What does Aquinas mean by ‘cause’ here? To answer this, we need to distinguish between what Aquinas calls an ‘efficient cause’ and a ‘formal cause’.

The efficient cause explains how something comes to exist, while the formal cause explains how something is the particular kind of thing it is. Thus, the efficient cause of some x is the agent that brings x into being, but the formal cause of x is x’s defining characteristics (or ‘formal characteristics’, as the medievals put it), for those are the characteristics that make x the sort of thing it is.

For example, the efficient cause of a clay statue is the sculptor, for that’s who made it. Without the sculptor’s activity, the statue wouldn’t exist. But the formal cause of the statue is its statue-shape, for that’s what makes it a statue. After all, if the sculptor gave the clay a vase-shape, that’d make it a vase, not a statue.

So does Aquinas think incompatible features are efficient or formal causes of distinction? Surely he doesn’t think they’re efficient causes. Taking sides on capital punishment divides people into two groups, but the viewpoints themselves don’t literally twist people’s arms and force them into two groups. As the saying goes, viewpoints don’t kill people, people kill people.

But the ‘for’ and ‘against’ viewpoints are formal causes of division. Their formal/defining characteristics are such that one and the same individual can’t hold both viewpoints simultaneously. Thus, they require separate advocates: one to take the ‘for’ side, and another to take the ‘against’ side.

Besides, features depend on the things they belong to, not the other way around. A sports car has the feature of being red, but its red color depends on the car for its existence; the car doesn't depend on its red color. After all, I could re-paint my car, and the car would still exist, but if I destroyed the car, any color it might have would cease to exist too.

Consequently, features can't be the efficient cause of distinction. Features come on the scene too late, as it were, to cause any distinctions. For this reason alone, incompatible features can’t be the efficient cause of distinction (though they can be the formal cause of distinction).
I take it, then, that Aquinas thinks incompatible features are the formal cause, not the efficient cause, of distinction. When he says that two incompatible features F and G are the ‘cause’ of distinction, he means F and G formally require distinct things. He doesn’t mean that F and G efficiently cause distinct things to come into being.

(Note that this seems to be a priori or ‘self evident’ in the sense that the consequence is included in the antecedent. Here, incompatible features are defined as features that can’t exist in the same thing (A3 above). But to say that incompatible features are the ‘formal cause’ of distinction is just to say that incompatible features can only exist in distinct things.)

(c) The third point that needs clarification focuses on Aquinas’s claim that two features are compatible so long as they’re not opposites. We need to be careful here. How wide is Aquinas casting this net? He’s supposed to be talking only about spirits, but his example of whiteness and triangularity is taken from the material world. So is Aquinas talking about any two features (be they spiritual or material), or is he only talking about spirit features? If it’s the former, then Aquinas is saying this:
(A4) For any features F and G, F and G are compatible iff F and G are not opposites.
But if it’s the latter, Aquinas is saying this:
(A4*) For any spirit features F and G, F and G are compatible iff F and G are not opposites.
These are very different claims. The fact that Aquinas talks about whiteness and triangularity makes it tempting to think that he is affirming the former claim (namely, A4). After all, spirits are neither white nor triangular, so it certainly appears as if Aquinas is thinking that this rule applies to more than just spirits.

The problem is, Aquinas thinks A4 isn’t always true. Individual material substances are incompatible according to A3, but they’re not opposites. Socrates and Plato, for example, obviously can’t exist in the same thing, but they’re not opposites. Thus, Aquinas should reject A4.

Perhaps he holds A4* instead. That would support his initial claim (A1 above) that all spirits are distinct because they’re opposites. But if that’s right, I still wonder why Aquinas uses whiteness and triangularity as an example. Maybe it’s just a bad example, and that’s all there is to it.

Now, it’s well known that for Aquinas, material beings are distinct because they occur in different lumps of matter, but angels are distinct because they belong to different species. For Aquinas, a species gets divided up into different individuals when its instantiated in different lumps of matter, roughly similar to the way a cookie cutter’s shape gets replicated when it’s stamped into different lumps of cookie dough. (So Socrates is the human-species ‘stamped’ into this lump of tissue, and Plato is the human-species ‘stamped’ into that lump of tissue.) But angels don’t have any matter, so any given angel-species can’t be replicated by being ‘stamped’ into different lumps of matter. Thus, each angel is the sole member of its species. Moreover, each angel just is its species, much like how there’s nothing but the cookie cutter’s shape if there aren’t any lumps of cookie dough to take on that shape.

Given this, we might think that Aquinas believes that although distinct material beings (in the same species) aren’t opposites, distinct species are opposites. That would support the initial claim (A1), for although Aquinas is willing to accept that material things are distinct without being opposites, there is no matter in the realm of angels, so the only distinction there is one between species, and species are distinct only because they’re opposites.

But if that’s right, then what is it that makes species opposites? Every species is a complex of a shared genus and a unique specific difference. For example, the human species is composed of animality (the genus that humans share with other animals), and rationality (the specific difference that belongs uniquely to humans, and so distinguishes humans from other animals). Thus, any opposition between species would have to occur between the specific differences. After all, the genus is shared, and shared things can’t be opposites. But does Aquinas really think that specific differences are opposites?

That seems to be the moral of the story here. Consider the human- and brute-species. These are distinct because the former has rationality and the latter does not. Rationality and irrationality seem to be opposites, so perhaps that makes sense. Maybe, then, Aquinas is using opposition to explain how species themselves are distinct.

Still, this leaves many questions unanswered. If specific differences are opposites, what, exactly, are opposites? How does one define ‘opposites’? Are there different kinds of opposites? If so, which kind do specific differences fall under?

In any case, now that we’ve gone through all that, we’re in a better place to summarize Aquinas’s argument. As I hope is clear by now, Aquinas argues that non-opposing features are compatible, so they’re perfectly happy to exist in the same thing. (Well, in the material world, material substances can be incompatible without being opposites, but we’re talking about the realm of spirits here.) Consequently, non-opposing features can’t be the formal cause of distinction between spirits, for there’s nothing about such features which demands that they exist in distinct things.

Opposite features, on the other hand, are incompatible, so they cannot exist in the same thing. On the contrary, opposite features can only exist in distinct things. Thus, opposite features must be the formal cause of distinction for spirits.

Unfortunately, A4/A4* are contentious. Neither A4 nor A4* are universally agreed-upon claims. Ockham, for example, thinks that angels are individuals just like Socrates and Plato, and all individuals are primitively distinct (without being opposites). So Aquinas’s argument is only as successful as A4/A4*, and not everybody buys A4/A4*.

1 comment:

Scott Williams said...

Interesting stuff here. It makes sense that if we are doing some method of division that after we look at a common essence (genus) we come to a fork in the road, either e.g., rational (specific difference) or irrational (specific difference). Now, it'll be interesting to see how this is applied to the Trinity case. If this is the view that Aquinas brings to the Trinity, then are e.g., paternity and filiation opposites, in the sense that there is something common (divine essence) but there are two possible differences: paternity or filiation. If that is how things go, then isn't this a genus-species model for the divine essence and personal properties? I imagine Aquinas doesn't go this route -- but it seems one possible route from what he says of 'opposites' here.