10a. Aquinas and the Cosmological Arguments. Part 1/2.
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Nothing gets people talking like proving the existence of God -- just look at the comments on our last video. And that is what Anselm of Canterbury did. He claimed, in the 11th century, to have come up with deductive proof of God's existence, through what we now know as the ontological argument. And, if there was such a thing as a social network of medieval Christian philosophers back then, it was positively abuzz with the news. For a long time. Because, almost 200 years later, Italian theologian and philosopher Thomas Aquinas encountered Anselm's argument. But, like many others, he just didn't buy it. Aquinas did believe in God. It was just that, as a philosopher, he felt that it was important to have evidence for your beliefs. He knew that if he was going to dismiss Anselm's argument, he'd need to come up with something better. So, he set out to construct five arguments that would prove God's existence, once and for all. Yeah, five. Apparently, he was concerned one wasn't going to do it, so he figured that, out of five, one was bound to stick. His first four arguments are known together as the cosmological arguments, as they seek to prove God's existence through what he argued were necessary facts about the universe. So, in keeping with the method that we discussed in our very first episode, we're going to examine these first four arguments of Thomas Aquinas -- and really try to understand them. And then we'll consider their merits… ...and their weaknesses. [Theme Music]
Maybe the most striking thing about the cosmological arguments of Aquinas, at least to modern eyes, is that some of them are firmly based in the natural world. Even though he lived in a pretty unscientific time, Aquinas argued for the existence of God through his understanding of science, and with the help of what he thought was physical evidence.
For example, the first of his cosmological arguments is known as the Argument from Motion. In it, Aquinas observed that we currently live in a world in which things are moving. And he also observed that movement is caused by movers -- things that cause motion. Aquinas was convinced that everything that's moving must have been set into motion by something else that was moving. By this logic, something must have started the motion in the first place.
Otherwise, you'd be stuck in a philosophical quandary known as an infinite regress. You get an infinite regress when, in a chain of reasoning, the evidence for each point along the chain relies on the existence of something that came before it, which in turn relies on something even further back, and so on, with no starting point.
Basically, Aquinas thought the very idea of infinite regress was absurd, logically impossible. Because, it implied that any given series of events began with…nothing. Or, more accurately, never really began. Instead, it could have been going on forever. In the case of physical motion, Aquinas wanted to trace the cause of the movement he saw in the world all the way back to its beginning. And he figured there MUST have been a beginning.
Otherwise, for him, it would be like watching these blocks fall, and being told that nothing ever pushed over the first block. Instead, they had always been falling down forever, backward into eternity. There must have been a time when nothing was in motion, Aquinas thought, and there also must've been a static being that started the motion. And that being, according to Aquinas, is God – the Unmoved Mover.
So his Argument From Motion ran something like this: Objects are in motion Everything in motion was put into motion by something else. There can't be an infinite regress of movers So there must have been a first mover, itself unmoved, and that is God Now, the second cosmological argument of Aquinas was a lot like his first one. Here, he proposed the Argument from Causation, and it, too, sets out to avoid the problem of an infinite regress. But instead of it explaining the motion of objects, it set out to explain causes and effects, in general, all over the universe.
The argument went along these lines: Some things are caused. Anything that's caused has to be caused by something else (since nothing causes itself.) There can't be an infinite regress of causes So there must have been a first causer, itself uncaused, and that is God Just like with the Argument from Motion, the point here is pretty simple: Effects have causes. If you think about how you wound up watching this video, you can trace the line of causation back, from moment to moment. If you think about it long enough, you can probably go pretty far back. But Aquinas said, again: It can't go back forever. There had to be a First Thing that started off the chain of causes and effects. And that Thing is God. Argument number three was the Argument from Contingency. And we should step back and get a little background for this one. In philosophy, we often distinguish between necessary beings and contingent beings. A contingent being is, simply put, any being that could have not existed. That includes you. Sure, you do exist, but you could not have.
If you had never been born, the world would go on. And yes, things would be different – we've all seen It's A Wonderful Life – but the world would go on. Instead, your existence is merely contingent on the existence of other things. In your case, you only exist because a certain sperm met a certain egg and swapped some genetic information. You're basically a fluke. But what does that have to do with God? Well, again, Aquinas believed that there had to be something that prevented an infinite regress of contingency. That would mean that the contingency on which everything existed would just keep going back in time. And we can't have a world where everything is contingent, Aquinas said, because then -- by definition – it all could easily have never existed. So he needed at least one necessary being – a being that has always existed, that always will exist, and that can't not exist, in order to get everything going. And that necessary being is God.
