Friday, February 17, 2006

Is God "Pure Act"?

According to classical theism (as exemplified by Aquinas), God is "Pure Act". What does that mean, you ask? Good question. The idea goes back to Aristotle, but we'll pick it up with Aquinas.

Very early on in the Summa Theologiae Aquinas says the following:
For motion [motus, i.e., change] is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself. (ST I.q2.a3)

The first being must of necessity be in act, and in no way in potentiality. For although in any single thing that passes from potentiality to actuality, the potentiality is prior in time to the actuality; nevertheless, absolutely speaking, actuality is prior to potentiality; for whatever is in potentiality can be reduced into actuality only by some being in actuality. Now it has been already proved that God is the First Being. It is therefore impossible that in God there should be any potentiality. (ST I.q3.a1)
The first quote is from the first of Aquinas' famous "Five Ways". In the second quote Aquinas draws out what he takes to be the implications of the First Way: the "first mover" must be wholly "in act". Hence, the idea that God is "Pure Act".

Aquinas and other medieval theologians clearly took this to be a very important and defining attribute of God. But what does it mean? I must confess that I find the notion rather opaque. Aquinas' discussion in the First Way suggest that "act" and "potency" satisfy at least the following contraints:
  1. They are contraries: To be in act in some respect precludes being in potency in the same respect, and vice-versa.
  2. Act is causally prior to potency: It takes something in act in the relevant respects to actualize any given potency.
  3. No self-actualization: Nothing that is in potency in some respect can actualize itself in that same respect. (This follows from (1) and (2).)
To illustrate, Aquinas gives one example: something that is actually hot (fire) can make something that is actually cold but potentially hot (a log) to be actually hot.

This suggests that Aquinas has in mind something like one of the following ways of characterizing the act/potency distinction:

A. With Respect to Predication
  • substance X is "in act" wrt property Y iff "now exemplifies Y" can be truly predicated of X.
  • substance X is "in potency" wrt property Y iff "now exemplifies Y" cannot be truly predicated of X, but in some causally possible future "now exemplifies Y" can be truly predicated of X.
B. With Respect to Perfection
  • substance X is "in act" wrt property Y iff X is in a state of perfection wrt Y and has the capacity to perfect that which is in potency wrt Y.
  • substance X is "in potency" wrt property Y iff X is perfectible with respect to Y.
Thomist Henri Renard ("The Philosophy of Being"): "Act is a perfection, and potency is capacity for perfection. Act is a reality which perfects, actuates the potency in which it is received, but in no way destroys it. Potency ... is a positive capacity for receiving this perfection."
Definition (A) seems to be a tolerably clear way of articulating the act/potency distinction with respect Aquinas' fire-and-log example: Initially we can truly predicate "exemplifies hotness" of the fire but not of the log. As the fire heats the log, however, the log changes so that we can predicate "exemplifies hotness" of it. (Note that this is an example of deterministic causation in which one existing thing brings about a change in another existing thing.)

Definition (B) is murkier both because of the undefined term "perfection" and because the notion of "potency" occurs in the definition of actuality. Offhand, it's not clear how a log's becoming hot is a reception of a "perfection". For some extrinsic purposes a hot log may be better than a cold one, but there doesn't seem to be anything intrinsically better about hot logs versus cold ones. So how is it that the log itself has been "perfected"? Perhaps heat is supposed to be a "perfection" that comes to reside in the log. Okay, but how exactly is heat a "perfection"? Definition (B) doesn't seem to fit Aquinas' example very well.

One difficulty in making sense of Aquinas' notion of God's "Pure Actuality" is that his clear examples only support something like (A), whereas Aquinas wants something like (B). Another difficulty is that the deterministic implications of (A) work themselves into Aquinas' theology where they create problems.

Principle (3), for example, is plausible when applied to inanimate things like logs, but it seems false when applied to persons. In my view, part of what it means to be a person is to have a power of self-determination, i.e., to be a self-moved mover, a self-actualizer. As a free agent I have the power to be a first cause of at least some of my own actions. For example, I can decide right now to raise my left arm. God, the preeminent agent, is free to create or not, and he is free to decide how to respond to our actions and prayers. In making free decisions we actualize a potency in ourselves. When God chooses to create he actualizes his potency to be a Creator. Or so it would seem.

What's more, for Aquinas, God's "Pure Actuality" entails God's absolute immutability and impassibility, both very difficult doctrines to defend. On the face of it God's freely creating (not to mention the Incarnation) is a change in God: We seem to have a state in which God alone exists followed by a state in which God and creation exist.

I suspect that Aquinas' views on God's absolute immutability and impassibility result from over-reliance on deterministic efficient causal, fire-heating-wood examples of the act/potency distinction, leading to an oversight of the fact that perfection in a person consists significantly in the power of self-determination or agent causation. Furthermore, it is arguable that being in loving relationship is the highest kind of good for a person, in which case perfection in a person also consists significantly in receptivity to another.

What if Aquinas had taken for his model of act/potency something distinctively personal? Take, for example, the act of welcoming. When person A welcomes person B, actively listens to B, etc., A opens himself to be influenced by B. A is being both active and receptive at the same time. If Aquinas had taken something like that for his paradigm of act/potency, then maybe he could have a God who is "Pure Act" in the sense, perhaps, of "Perfect Love" as I have characterized it here, without having to embrace either absolute immutability or impassibility.


At 2/20/2006 2:55 PM, Blogger shulamite said...

I need a bit of clarification on your principle #3. Let me set it up like this:

I have a joke that I tell my students when I am explaining Aristotle, it goes like "would you trust a plummer to do heart surgery?" (of course everyone says "no") then I hit them with the punchline "Well then, we shouldn't let them every go to medical school!"

The distinction at play here is one between the perse and the per accidens, and I think it might help your "self-actualization" puzzle. You say that nothing in potency in one respect can actualize itself in that same respect. I agree if you mean that no plummer, in virtue of being a plummer, can do heart surgery. But if you mean that a plummer can do it in virtue of his some skill he picked up at medical school, then he can. In other words, in your #3, a thing cannot bring itself into act inasmuch as the thing has potential, but only inasmuch as it has act.

If we take take this as the way to understand principle #3, then we can allow both for the truth of what Aquinas is saying, and your observation that every person can be a true self- mover. Aristotle, in fact, sees every natural thing as a sort of self-mover- he sees nature as like "a doctor healing himself".

At 2/20/2006 10:37 PM, Blogger Alan Rhoda said...

Interesting thoughts, shulamite.

(3) comes directly from Aquinas' First Way: "Nothing can be reduced from potentiality to actuality, except by something in a state of actuality....Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects."

In your plummer/doctor example, I think there are two distinct levels of act/potency at work. The plumber who's been to medical school has acquired a first-order potency to practice medicine. That potency is actualized whenever the plumber does practice medicine. But the plumber who has not been to med school does not have a first-order potency to practice medicine, but only a first-order potency to acquire a first-order potency (i.e., a second-order potency) to practice medicine. That potency is actualized by going to med school.

A rock for Aristotle is a self-mover in the sense that it has a natural motion toward the center of the Earth. This potency is always actualized in the rock--it's always trying to move downward--because that's its nature. Human persons seem to be different. Unlike rocks, we have choices to make, choices that are not determined by our natures. But given principle (3) and the contingency of human choice, we run into problems: Suppose I have a genuinely contingent choice to make between A and not-A. Because I am not in act with respect to doing A, my potency to do A must be actualized. But that actualizing of A is not itself actualized (since I haven't made my decision yet), so it too is a potency that needs to be actualized. Thus, I have to actualize my potency to actualize my potency to do A. But that actualizing my potency to actualize my potency to do A is not itself actualized, so it too is a potency that needs to be actualized, etc.... Given principle (3), the contingency of human choice leads to a vicious explanatory regress. Since that's unnacceptable, we're forced to deny the contingency of human choice. If (3) is true then appearances to the contrary we are no more free agents than a rock.

What generates the regress here is (3), the idea that nothing can be in act and in potency in the same respect at the same time. But I want to suggest that distinctively personal actions like loving and welcoming are counterexamples to (3). My loving my wife is both active and receptive at the same time in respect to the same person.

At 2/27/2006 9:48 AM, Blogger C Grace said...

"my potency to do A must be actualized." Must it be actualized by us?

Can this be actualized by God? According to Aquinas God is also pure being. I am not sure whether I can express this correctly but our being is contingent upon God's ever present act within us. God has given us a limited amount of potency which can be actualized by us because within us is the actuality given us by God.

Imagine us as a rock which God has thrown that has some limited ability to steer itself.

About the fire being a perfection. Doesn't Aquinas like some others I have read basically have the belief that the spiritual is a perfection over the physical? In the middle ages I think spiritual was anything non-physical, so heat 'freed' the log from it's physical limitations. My understanding of the mindset is rather vague, but I think it is important to realize how our scientific understanding has changed the way we see things.

At 2/27/2006 9:53 AM, Blogger C Grace said...

Just one more question. I have been reading Ascent of Mt Carmel, St. John of the Cross.In it he says

"It must be known that the affection and attachment which the soul has for creatures renders the soul like these creatures...for love creates a likeness between that which loves and that which is loved."

Do you know if this idea of love originates with Aquinas?

At 2/28/2006 4:50 PM, Blogger shulamite said...

In order to contradict Aquinas, you must show that something is in potency and act at the same time and in the same respect. In other words, you must claim that something is in act and non- act in the exact same respect.

What Aquinas is saying is simply the principle of contadiction, applied to potency and act.

At 3/01/2009 7:36 PM, Blogger JT Paasch said...

Maybe the following will help.

Potencies are causal powers. Active potencies are powers to do things, and passive potencies are powers to have something done to you.

Most scholastics distinguish between natural and voluntary powers. Natural powers are automatically manifested/exercised whenever and wherever they can. A flame, for instance, will heat any combustible material that gets near enough, so long as there are no obstacles.

Voluntary powers, by contrast, are exercised at will. Powers to choose, love, etc. -- the scholastics believe these are all voluntary powers.

Natural powers cannot be self-actualized, but voluntary powers can.


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