It’s an interesting little curio this week – Aquinas on God’s omnipotence. He brings up all the tedious smug little arguments that people make about omnipotence, proving that a) they’ve been around forever and b) the people making those arguments are less interested in hearing the answers and more interested in being smug and tedious. We also get a surprise visit from C.S. Lewis!

This section is 1a.25.3. There’s four main arguments that are advanced and refuted, but they’re not all equally interesting. If you want to look the others up, you can – but I’ll just cover these for now. The first argument is that God is changeless – if He’s all-powerful, why can’t He change? The second argument is that God can’t sin – again, just something He can’t do.

Aquinas begins his rebuttal by drawing a distinction between things that are broadly thought of as impossible and things that are contradictions in and of themselves. So this is the old ‘Can God make a burrito so hot that He can’t eat it’ thing – it’s a contradiction in terms. Either He can’t make the burrito, or He can’t eat it, and in either situation omnipotence is supposedly disproved. There’s lots of variants – a stone too heavy to lift, and so on – and frankly they’re pretty boring. But Aquinas wants his due diligence, so here we are.

Aquinas suggests that the divine being is infinite existence, “not limited to any kind of being, but holding within itself and anticipating the perfection of the whole of existence.” Everything that can exist finds the ground of its being in God. Thus God is all-powerful in the sense that everything that can exist falls within the purview of His power. The burrito too hot for God to eat cannot exist – it’s a paradox. Similarly, we might say that Socrates (Aquinas loves his Socrates examples) cannot be both sitting and standing at the same time. It’s a contradiction in terms. So technically, no, God cannot create a burrito so hot that He cannot eat it. But that doesn’t mean God’s not omnipotent, it just means that omnipotence doesn’t cover paradoxes. Rather, omnipotence means that everything that can exist is within the purview of God’s power.

In making this argument, Aquinas borrows Aristotle’s distinction between the relatively and the absolutely possible. If something is relatively possible, it’s possible dependent on the circumstances. If something is absolutely possible, it’s possible in the sense that it may exist. It doesn’t necessarily exist, but it is absolutely possible – that is, in absolute terms, it’s not impossible that such a thing might exist. Paradoxes fall outside of the realm of the absolutely possible. It is impossible that such things might exist, because they are contradictions. For Aquinas, then, God is able to do everything that is absolutely possible. That’s what omnipotence means.

So then, why can’t God change? Aquinas has a long-running distinction between actuality and potentiality – we might think of it as the distinction between energy and potential energy. That is, if you’re holding a ball up in the air, it has potential kinetic energy, meaning that if you let it go, it’ll express that energy by falling. While you’re holding it, though, the energy remains potential. It’s not being expressed just yet. Aquinas’s distinction goes further though – so for example, you as a human being have the ability of speech. A whole bunch of words are stored up in your brain, and you’re not saying them, but they exist in there. Those words are, in Aquinas’s terms, potential. They are things that it is within your power to do – within your power to say. When you actually come out and say them, they stop being potential words and become actual. But there are also a bunch of other potential aspects to you. You have the potential to be set on fire or rolled down the stairs. People can act on you and turn those potential elements into actual elements.

However, in God, Aquinas argues, there is only actuality. God has nothing potential within Him, nothing that can be brought out by acting on Him. In that sense, He cannot change because He is already pure actuality. And this is all part of His omnipotence. You cannot act on God and change Him because He is already pure actuality. There is no potential element yet to be drawn out of God – He’s all-powerful. In that sense, the inability to be changed is part of omnipotence. Technically you could say that it’s just another thing that God cannot do, but again, Aquinas argues that being unchangeable is part of omnipotence rather than contradicting its essence.

The same goes for sin – God cannot sin because sin is essentially a failure of activity. It’s a degradation, an inferior form. So for example there’s good sex, sex done right, and then there’s cheating on your partner, which is sex done wrong. It’s conceptualised as a failed form of sexual activity, as a lesser or inferior form. God cannot sin because He is all-powerful – He can’t just fail at doing something, or do it in the wrong way. He’s too good at everything to do anything wrong. Omnipotence therefore encompasses inability to sin.

I said that Lewis would make an appearance, so I suppose I’d better bring him in. Lewis basically follows Aquinas’s argument about paradox and omnipotence in Mere Christianity. He uses slightly different language, but basically repeats the same ideas. If God can do all things, paradoxes aren’t really things. They are, by definition, impossible. They’re nonsense, non-things, according to Lewis, and so it doesn’t really interfere with omnipotence to say that God can’t do them. They are outside of the realm of possible thing-hood. This is pretty standard behaviour for Lewis – most of the things he says in Mere Christianity are just pinched off other theologians. It’s not a bad thing, necessarily – and he acknowledges that he’s not really saying anything new. He’s much more a communicator of theological ideas rather than someone coming up with his own original thoughts, in that sense – at least for Mere Christianity.

The other thing about Lewis is that he’s drawing on an argument Aquinas made some 800 years ago. I said at the start that the burrito argument is made by smug, tedious people, and I meant it. I’ve never heard anybody use that argument who was also genuinely interested in learning more about God. They’re usually just shitty atheists trying to prove that religion is stupid by throwing up these kind of logic games. Usually, this sort of response won’t satisfy them – they don’t actually care about what you have to say or what you actually think about Christianity. They’re just trying to make the faith look incoherent. Obviously Christians have been thinking about these sorts of questions for – well, for at least 800 years. But I’ve yet to find someone who’s interested in the answers they put forward.