Having talked about God’s willing and His knowledge, together with things such as His providence that arise from them, it is quite natural for Aquinas to discuss God’s power; that by which God acts as an agent. We commonly call God infinitely powerful and also omnipotent, but what do these mean? A common objection to the notion of omnipotence is that it implies contradictions: if God is omnipotent what is to stop Him from creating a stone so heavy that He cannot lift it? Aquinas’s strategy is to pursue a careful line of enquiry as to what these terms mean, turning the common objections on their heads.
The Thread of the Argument
A1: Aquinas begins his discussion of the power of God by asking whether there is power in God. This does seem a very curious question but the very first objection against the thesis indicates the need for the precision that Aquinas will bring to bear throughout this question. The Latin word potentia, which is here translated as “power” can also be translated as “potentiality” and, as we have seen, God is pure actuality with no admixture of potentiality. This play on words indicates the need to distinguish between two kinds of potentia: a passive power that corresponds to the ability to be acted on by an agent, and an active power facilitating acting as an agent on other things. Clearly God has no potentia in the first sense but has it pre-eminently in the second sense. A number of objections are made that are each based on confusion about God’s simplicity. For example, power is a source of action (or actuality) but God’s actuality is his essence but His essence has no source. Aquinas replies that power, in the context of God, should properly be thought of in terms of the source of effects rather than of actions and this approach frees us from the contradiction. Similarly, as God’s knowledge and will are the cause of all things, the notion of power seems to be redundant. As before, Aquinas is willing to distinguish between what is real in God and what is conceptually useful for us in talking about God.
A2: We commonly think that there can be no limit to God’s power both in terms of amount and extent but this would seem to lead to problems when God applies His power to the created world. Any infinite power would seem to bring about an infinite effect; in particular, infinite force acting on a body would accelerate it to infinite velocity. But these are impossible. God’s active power clearly has to be infinite, as God’s essence is infinite (Question 7 Article 1), so the apparent contradictions must lie in confusion about How God’s power acts in creation. The confusion is twofold but basically arises from pushing the analogy of action within creation with God’s action too far. If a body were acting on another body with infinite power then we do indeed reach a physical nonsense. However, God is not a body nor does He act as a univocal agent. When the first body acts on the second its power is ordered entirely towards the single end of moving the second body. It has no “choice” in how it acts on the body; its action is strongly coupled and subordinated to the end of moving the second body. When God acts in creation He acts as a non-univocal agent whose power is not subordinate to any of its effects as an and. He chooses the end He wishes to achieve and uses as much of His power as is appropriate.
A3: Having dealt with the question of the infinitude of God’s power, Aquinas now turns to the question of the extent of God’s power: is God omnipotent? The problems that Aquinas has to face in this article are made clear in the objections: surely omnipotence means “being able to do anything”? But if God is omnipotent then he can act upon Himself; He can sin; He can create a weight that He cannot lift! Moreover, if God can do anything, then it would seem that what there is in the world and how it all fits together is entirely down to God’s will; there can be no notion of necessity in the world at all. Aquinas confesses that God is omnipotent but immediately admits that what omnipotence amounts to is non-trivial to determine. Aquinas’s solution is that God can do anything that is possible. What then does “possible” mean? According to Aristotle, one of the meanings of “possible” relates to what is possible to a particular power (this is called relative possibility). I can lift a fifty kilogram weight, but I cannot life a hundred kilograms. We might think that what is possible to God is simply the sum of all that is possible to created powers, but this seems far too restrictive. Neither can we say that God can do what is open to God’s power, as that would be circular. Aristotle’s second meaning of “possible” relates to what is absolutely possible. In this sense something is possible if it doesn’t involve an inherent contradiction. Put another way, a state of affairs is absolutely possible if it can have being. Nothingness is the only thing that contradicts being, so whatever simultaneously implies being and non-being cannot be absolutely possible and is beyond the remit of God’s omnipotence. Aquinas coins a neat way of putting it: “the best thing to say, however, is that they cannot be brought about, not that God cannot bring them about”.
A4: Having determined that God’s power stretches to all that is non-contradictory, Aquinas asks whether He can make the past not to have been. In other words (given article 3), is the mutability of the past inherently contradictory? In Question 10 Aquinas discussed time, aeviternity and eternity and it was clear there that understanding the relationship between a being that exists “in eternity” and beings that exist “in time” is a tricky philosophical problem. If one thinks of the analogy where God “looks” down on the four dimensional space-time universe, grasping all of it in one go, then it would not be too difficult to imagine that God may fiddle with what is in the past (as far as we are concerned). However attractive this analogy may seem, it can be misleading and Aquinas claims that to be able to change the past is inherently impossible. We feel perfectly at ease with the idea that saying Socrates is both seated and standing is a contradiction; Aquinas claims that to say Socrates was seated and was standing (simultaneously) is also a contradiction. If this little argument is not enough, the authority of Augustine and Aristotle are called on to bolster the argument.
A5: Since God foresees and pre-ordains what He actually brings about it would seem that God is unable to bring about what He does not bring about. In other words, God is constrained in what He brings about by what He actually brings about because of the way that He brings it about. Aquinas has already pointed out in Question 19 Article 3 that God’s will is not constrained by any natural necessity, so the fact that things have come about from God in the way they have is not a constraint on God. God was perfectly free to create the universe in whatever way He pleased. Similarly it is not correct to think of God’s plan of wisdom and justice as constraining Him. The confusion seems to lie in the fact that God brings all things to be in His single act of being; because we think of His single act of being under a number of different conceptual guises (His being, His essence, His power, His justice, His providence and so forth) we are liable to think of these different aspects constraining each other. We have to be careful not to allow these different conceptual approaches to God to obscure the single underlying reality. A further useful distinction to make that allows us to think coherently in terms of these conceptual distinctions without falling into the trap of thinking that their mutual inter-relationships constrain God, is between the Absolute Power of God and the Ordained Power of God. The absolute power of God refers to His radical freedom to bring about whatever He wills to bring about. His ordained power refers to His power to bring about whatever He has pre-ordained to bring about by reason of His just will.
A6: Having shown that God, by His absolute power, is not constrained in what He brings into being, we might ask whether He can make things better than He does. Aquinas answers this question by making a number of distinctions about how things could be made better. If we think of a particular thing then, as far as its essence goes, God cannot make it any better than it is because to do so would be to change its essence and therefore make it something different. He can, of course, make something different instead of what He has actually made. Although God cannot improve the essence of something without changing what it is, He can make its non-essential characteristics better; so a human can become wiser or more virtuous, for example.
- God’s power refers to His active power rather than to any notion of passive power or potentiality.
- God’s omnipotence reaches to everything that is consistent with being. This is sometimes formulated as the “Principle of non-contradiction”, that something cannot simultaneously be and not be.
- We distinguish between the Absolute Power of God and the Ordained Power of God. The former refers to His power to bring about whatever He wills, the latter to His power to bring about what He wills.
- In Article 3 Aquinas claims that God can only do what is inherently possible, in the sense of not involving a contradiction. He also states this in the form of saying that a state of affairs cannot simultaneously be and not be. Later thinkers such as Descartes claimed that part of God’s creative activity involves determining what the laws of logic themselves are. Therefore Aquinas’s “Principle of non-contradiction” is itself under God’s power. God could have made creation with different logical rules. This point of view is related to later medieval developments in the idea of the absolute power of God. As Aquinas himself observed, this idea is rationally incoherent, as our minds are subject to the laws of logic and anything outside this cannot be thought about: it is not to hard to turn the assertion itself into a contradiction (as far as our laws of logic are concerned!)
- The argument in Article 4 that the past cannot be changed depends on something in the past having a sort of absolute existence. To assert a different past is therefore to assert a simultaneous being and non-being, because the event in the past has real being. But what happens if one attempts to argue that God “changing” an event in the past involves that event never having had existence? It would seem that to do so, one would have to leave any coherent notion of philosophical realism behind.