Summa Theologiae, Questions on God

"The volume is essentially the first quarter or so of Part One of Summa Theologiae , where Aquinas addressed the topic of the existence and nature of God. This is the part of the book where Aquinas is approaching the question from the point of view of natural theology, as opposed to revealed theology. Later on in the Summa , of course, he brings in considerations from revealed theology, when discussing certain aspects of God’s nature such as the doctrine of Trinity. But, in the material that’s collected in this particular volume, he’s approaching the subject entirely from the perspective of philosophy. So, even someone who doesn’t share Aquinas’ commitment to Christianity would find much of value in this book and non-Christian theists would find nothing there that they would necessarily disagree with. It’s in this material that he presents his famous ‘Five Ways’ of arguing for God’s existence. That comes very early in the discussion and is part of how he gets the ball rolling in the discussion of God. I should say a little bit about the Five Ways because they’re very commonly misunderstood. First of all, the Five Ways are not original with Aquinas and he certainly would not claim that they are original to him. They are essentially five lines of argument that were in the air, as it were, at the time that he wrote. They were fairly well-known lines of argument, standard moves you might say, when presenting a case for God’s existence. That’s the first thing to notice: they are not original and are not presented as original by Aquinas. The other thing to notice, which is an extremely important point that is often overlooked, is that Aquinas did not intend for them to be standalone pieces of reasoning that would convince even the hardnosed sceptic on a first reading. The Five Ways are typically read these days out of context. They are often the only thing that a modern reader ever reads from Aquinas. A modern reader might encounter them in an anthology, and they only take up maybe two pages. So, they are ripped from context and read as though Aquinas intended them to be a one stop shopping source for learning about the existence and nature of God. Naturally, a modern reader reads them and thinks of all kinds of objections that someone might raise against them. The modern reader will then conclude that Aquinas is overrated, that he didn’t think of these obvious objections, and that he must have been really naïve if he thought anyone would find these arguments compelling. “The Five Ways are not original with Aquinas and he certainly would not claim that they are original to him. They are essentially five lines of argument that were in the air, as it were, at the time that he wrote” But that’s quite unfair because they weren’t intended to do that job. They were intended to do a very different job. In the context of Part One of the Summa Theologiae , they are merely intended to summarise in a brief way, you might say in an almost Wikipedia entry style, these five lines of argument that would have been familiar to readers of his day. As I tell my students, when you’re reading the Five Ways, think of them as the sort of thing you might read in an encyclopaedia article when what you’re looking for is just an overview of the basic idea. You are not looking for a defense that will convince the most hardnosed sceptic. The most hardnosed sceptic about evolution or quantum mechanics is not going to find an answer to all his objections by reading an encyclopaedia article on one of those subjects. That’s not what an encyclopaedia article is supposed to do. And so, an atheist is not going to find the answers to every objection that he might raise in this little two-page selection from the Summa . That was not what Aquinas was trying to do. He was trying to summarise lines of argument that he develops in much greater detail elsewhere and that other writers developed elsewhere because, again, these are not the private property of Aquinas. They were common lines of argument that the readers of his day would have been familiar with. There are aspects of some of the arguments that he gives for God’s existence that reflect his distinctive philosophical point of view. One of those is an argument that we will be talking about later when we discuss another one of my book choices. But in the Five Ways, especially, what is most striking about the arguments is what Aquinas has in common with previous thinkers in the tradition rather than how he differs from them. The first of the Five Ways is also known as the ‘argument from motion’. It begins with the Aristotelian analysis of how change works. Aquinas notes in the argument that we see in the world around us that changes of various types occur. It could be what Aquinas would call local motion, where an object moves from one point in space to another. It could be qualitative change like when an object changes colour such a banana going from green to yellow. Or it could be quantitative change as when a puddle changes size. What Aristotle famously argues is that what change of any of these kinds involves is the actualisation of a potential. It involves something going from being potentially a certain way to being actually that way. In the case of the banana, it goes from being potentially yellow to being actually yellow. That is how change is possible , contrary to pre-Socratic philosophers like Parmenides and Zeno who famously denied that change is possible. How then does change actually occur ? The way that the First Way proceeds is to say that the only way any potential ever becomes actual is if there’s something already actual that makes that happen: something actual that actualises the potential. The coffee in the cup next to me starts out hot, it’s potentially cold, and that potential is actualised; it becomes actually cold when the cold air in the room surrounding it cools down the liquid in the cup. As that example illustrates, we have a kind of regress of causes or changers. One thing is being actualised by another which is actualised by another and so on and so forth. What Aquinas is concerned with in this argument, just as Aristotle was, is a series of changers or movers that extends not backwards into the past but rather, you might say, ‘downwards’ here and now. Ultimately Aquinas thinks that for any change to occur here and now, there must be something here and now that is making that happen. If what’s making it happen is something that is itself changing, then there must be some other factor here and now that is causing that . The only way this can stop is if there is something here and now which can change everything else – which can actualise all those potentials – without itself being actualised. This is something that can move without being moved and change other things without being changed. And this is what Aristotle and Aquinas call the ‘unmoved mover’ of the world, or as I prefer to put it: the ‘unactualised actualiser’ of the world. This is a cause that actualises other things without itself being actualised because it’s already purely or fully actual. That’s the philosophical core of Aquinas’ conception of God. Everything else he says about God and God’s nature, when he’s doing natujral theology, is essentially grounded in an analysis of what something has to be like in order to be an unactualised actualiser. He cranks all the various divine attributes out of that basic concept. The basic way in which it works is this. Once Aquinas gets to a first cause – an uncaused cause – which is what he calls ‘pure actuality’, then we start asking about particular aspects of God’s nature such as the question of whether God can change. As I’ve already indicated, if change involves the actualisation of potential and God is purely actual and has no potential, then naturally he’s not capable of changing. If he’s not capable of changing, though, and we think of time as essentially the measure of change – which is the way Aristotle and Aquinas think about it – then God cannot be in time either. Anything in time is going to go from potential to actual and if God is purely actual then he must, therefore, be outside of time. He must be non-temporal or eternal. On Aquinas’ analysis, and here again he’s building on Aristotle, material things always of their nature exhibit potentiality. That’s really Aristotle’s and Aquinas’ core idea of matter. Matter is essentially the potential to take on form. So if God is entirely actual – if God is pure actuality with no potentiality – then there must be nothing material in God either. Matter always involves the potentiality to change. Just think of ordinary experience. Something material might be broken up into its constituent parts and undergo change in that way. Something that’s unchangeable, though, because it’s pure actuality with no potentiality, must accordingly be immaterial as well as atemporal as well as unchangeable. “If he’s not capable of changing, though, and we think of time as essentially the measure of change – which is the way Aristotle and Aquinas think about it – then God cannot be in time either.” And then we come to other attributes like omnipotence. For Aquinas, what it is to be powerful is essentially to be able to actualise potential. It’s the ability to change or alter other things, to produce effects. On Aquinas’ analysis, anything that’s changing is going to be traced to the activity of the unmoved mover or the ‘unactualised actualiser’. So there is no power that’s exercised in the world, and there’s nothing happening in the world, that’s not ultimately derived from what the unactualised actualiser is doing. In that case, all possible or actual exercises of power are ultimately traceable to the unmoved mover. He is the source of all power. And, thus, he’s all-powerful. Then there’s also the question of monotheism. What Aquinas is going to argue is that the only way you can make sense of there being more than one member of some category of things is if there is some potential that one member of the category exhibits that the other member does not. But if we’re dealing with something that is purely actual and in no way potential, then there’s not going to be – even in theory – a way to distinguish one member of that class from another. There’s not going to be any potential that one of them has that the other one does not have. For example, the way we distinguish two human beings or two dogs or two chairs has in part to do with the fact that they are associated with different bits of matter. There’s a bit of matter that makes up my body and there’s a bit of matter that makes up another person’s body. But, as I said earlier, matter is for Aquinas associated with potentiality. Since an unmoved mover has no potentiality and is purely actual – and is therefore immaterial – then you’re not going to be able to distinguish one prime mover from another by associating them with different material bodies. It’s going to turn out that any other way in which you might try to distinguish one unmoved mover from another is similarly going to bring in the idea of potentiality. Potentiality is excluded from the very nature of an unmoved mover and so too is the possibility of there being, even in principle, more than one unmoved mover. So, we have the idea of divine unity or monotheism. This is a very common objection. You could even say that it’s the core objection that atheists tend to have to the very possibility of a first cause argument for God’s existence. If everything has a cause, then what caused God? If you say that God doesn’t have a cause, then why can’t we just say that the universe doesn’t have a cause either? In which case, the first cause argument for God fails. That’s the objection. But it’s a very bad objection. One of the interesting things about it is that you find that people who raise this objection – and it’s not just pop atheist writers like the New Atheists but also professional academic philosophers as well – they never cite any actual philosopher who gives the argument that they are objecting to. They are never able to cite a philosopher who actually gives the argument ‘everything has a cause, so the universe has a cause’. Certainly, they won’t find it in Aristotle or in Aquinas. It’s a sort of urban legend that is constantly attacked even though it’s not an argument that any prominent philosopher has ever given. Not only does Aquinas not give that argument, he would actually reject the premise that everything has a cause. What Aquinas is committed to is not the thesis that everything has a cause. Instead, his arguments proceed from premises like ‘whatever undergoes change requires a cause’ or to be more precise: ‘whatever goes from potential to actual requires a cause’. Or it might be formulated in a different way by saying ‘whatever is contingent requires a cause’, meaning whatever exists but could in theory have failed to exist requires a cause. But that’s as different from saying that everything requires a cause, as saying that ‘triangles have three sides’ is different from saying ‘all geometrical figures have three sides’. It’s a very different claim. “They are never able to cite a philosopher who actually gives the argument ‘everything has a cause, so the universe has a cause’. They won’t find it in Aristotle or in Aquinas. It’s a sort of urban legend that is constantly attacked even though it’s not an argument that any prominent philosopher has ever given.” For Aquinas, what makes it the case that something needs a cause in the first place is precisely that it has potential that needs to be actualised. So, there has got to be something already actual that makes that happen. But if there’s something that has no potential to be actualised, then not only does it not need a cause – because there’s nothing potential there to be actualised – but it could not even in theory have had a cause in the first place. Of course, someone might try to take issue with the reasoning that leads Aquinas to the conclusion that there is such a thing as an unmoved mover or purely actual actualiser of the world. But to raise the objection ‘if everything has a cause, then what caused God?’ simply misses Aquinas’ point entirely. It’s based on the assumption that Aquinas is committed to the premise that everything has a cause, which he is not. And it completely ignores the very reason why Aquinas characterises God as uncaused. He’s not making an arbitrary exception to a general rule. Rather, the whole point is that what makes something in need of a cause in the first place is that it has potential in need of being actualised. This precondition of something’s needing a cause does not apply to God."