Aquinas' Second Way: Proof of God's Existence as the Uncaused First Cause, Study notes of History

Download Aquinas' Second Way: Proof of God's Existence as the Uncaused First Cause and more Study notes History in PDF only on Docsity! Aquinas’ Five Ways Today we begin our discussion of the existence of God. The main philosophical problem about the existence of God can be put like this: is it possible to provide good arguments either for or against the existence of God? We will be considering a few traditional arguments for the existence of God, and the main argument against the existence of God, the ‘argument from evil.’ The main positions on the question of the existence of God are three: • Theism, the belief that God exists. • Atheism, the belief that God does not exist. • Agnosticism, not believing that God exists and not believing that God does not exist. The first three arguments for the existence of God which we’ll be discussing are all among the proofs of God’s existence offered by St. Thomas Aquinas. Thomas offered 5 proofs for God’s existence; of the two which we will not be discussing, one is the topic of your first paper. Thomas was born in 1225 and, while his works were extremely controversial in their time -- some were condemned as heretical by the bishop of Paris -- he has since come to be regarded as the greatest theologian and philosopher in the history of the Church. His Summa Theologiae -- from which the arguments we will be discussing were taken -- is regarded by many as the definitive exposition of the Catholic faith. We begin with Aquinas “second way” -- his second argument for the existence of God. In order to evaluate this argument, our first task is to identify Aquinas’s premises. We begin with Aquinas “second way” -- his second argument for the existence of God. In order to evaluate this argument, our first task is to identify Aquinas’s premises. One key premise seems to be his idea that nothing can be the efficient cause of itself -- i.e., that Nothing can be the cause of its own existence. So far, then we have two premises, and a pair of conclusions. The pair of conclusions was: A. There is a cause of the existence of some things which was not itself caused to exist. B. This “first cause” is God. A first question: is how are these two conclusions related? A plausible thought in this case seems to be that what Aquinas is really after is a proof of the existence of God. So conclusion A above is really just a kind of preliminary conclusion; the idea, Aquinas seems to think, is that if we can give an argument for A, we will then be in a position to get from there to the conclusion, B. So let’s focus first on how we could get to conclusion A. A natural first thought is that perhaps this conclusion simply follows from the two premises which we have already identified, namely Nothing can be the cause of its own existence. The chain of causes of things coming into existence cannot be infinite. If this is right, then the following argument should be valid: Nothing can be the cause of its own existence. The chain of causes of things coming into existence cannot be infinite. -------------------------------------------------------------------------------- There is a cause of the existence of some things which was not itself caused to exist. Is this argument valid? It seems that this argument is not valid. After all, we can imagine that nothing has ever been caused to come into existence. If that were true, then both premises would be true, and yet the conclusion would be false. How can we fix this problem with Thomas’ argument? Often, you can repair an invalid argument by adding an extra premise which makes explicit an assumption that the author had in mind. In this case, suppose we add the assumption that at least one thing has been caused to come into existence: 1. At least one thing has been caused to come into existence. 2. Nothing can be the cause of its own existence. 3. The chain of causes of things coming into existence cannot be infinite. -------------------------------------------------------------------------------- C. There is a cause of the existence of some things which was not itself caused to exist. If this really is what Aquinas had in mind, why didn’t he make this extra premise explicit? Is this argument valid? Can you think of any way in which premises 1, 2, and 3 could be true, and yet the conclusion false? We haven’t quite finished with the task of figuring out what Aquinas had in mind; after all, we know that he is trying to give an argument for the existence of God, and the above argument only gives us the conclusion that there is something which brings things into existence but was not itself brought into existence. But, fortunately, it is pretty clear what is going on here; from the way that Aquinas states his conclusion, it seems clear that he thinks that if there is such a first cause, then God exists -- because that first cause is God. Adding this to our argument, we get the following: 1. At least one thing has been caused to come into existence. 2. Nothing can be the cause of its own existence. 3. The chain of causes of things coming into existence cannot be infinite. 4. There is a cause of the existence of some things which was not itself caused to exist. (1,2,3) 5. If there is a cause of the existence of some things which was not itself caused to exist, then God exists. -------------------------------------------------------------------------------- C. God exists. (4,5) Is this argument valid? Note that answering this question is a bit more complicated than it was in the case of the arguments we discussed last time, since this argument contains a sub-argument: the argument which has premises 1, 2, and 3 as premises, and premise 4 as conclusion. So we have to ask both whether this sub-argument is valid, and whether the argument from 4 and 5 to C is valid. Aquinas’ 2nd way 1. At least one thing has been caused to come into existence. 2*. Nothing can be the cause of its own existence, or be causally responsible for its own existence. 3. The chain of causes of things coming into existence cannot be infinite. 4. There is a cause of the existence of some things which was not itself caused to exist. (1,2,3) 5. If there is a cause of the existence of some things which was not itself caused to exist, then God exists. --------------------------------------------------------- C. God exists. (4,5) This shows how much work is often required just to come up with a valid version of an author’s argument. And, of course, doing this is just half of our job: we want to know whether the argument is not just valid, but also sound. To figure this out, we have to ask: are any of Aquinas’ premises false? If not, then we will have a sound argument for the existence of God. Aquinas’ 2nd way 1. At least one thing has been caused to come into existence. 2*. Nothing can be the cause of its own existence, or be causally responsible for its own existence. 3. The chain of causes of things coming into existence cannot be infinite. 4. There is a cause of the existence of some things which was not itself caused to exist. (1,2,3) 5. If there is a cause of the existence of some things which was not itself caused to exist, then God exists. --------------------------------------------------------- C. God exists. (4,5) This shows how much work is often required just to come up with a valid version of an author’s argument. And, of course, doing this is just half of our job: we want to know whether the argument is not just valid, but also sound. To figure this out, we have to ask: are any of Aquinas’ premises false? If not, then we will have a sound argument for the existence of God. We can immediately eliminate premise (4) from consideration. After all, premise (4) is supposed to follow from 1, 2, and 3, and we have already agreed that the argument is valid; so, it seems that if the first three premises are true, premise 4 must be as well. Can we give any other defense of the assumption that the chain of causes of things coming into existence must be finite in length? One way to argue for this would be to show that there is some sort of absurdity in the idea of an infinite chain of causes of events. One attempt to show this is the example of “Thomson’s lamp”: a lamp which is turned on and off an infinite number of times between 3:00 and 4:00 one afternoon. The infinite series of events then can be represented as follows: on, off, on, off, on, off .... and so on, without end. Because there is no end to the series, every “on” is followed by an “off”, and every “off” is followed by an “on.” So it seems that at 4:01 the lamp can be neither on nor off. But this is absurd; there is no other state for the lamp to be in. If this shows anything, it shows that there cannot be an infinite series of events in a finite time. Can you see why? What does this tell us about premise 3? A further problem with the argument concerns premise 5: 5. If there is a cause of the existence of some things which was not itself caused to exist, then God exists. There are two different sorts of worries about this premise. The first is that, strictly speaking, the premise should say that if there is at least one cause of the existence of some things which was not itself caused to exist, then at least one God exists. After all, nothing rules out the chain of causes looking like this: This would be a non-infinite causal chain in which nothing is causally responsible for its own existence; but there are two uncaused causes in this chain, not one. Since the idea that the chain of causes has this shape is consistent with everything in Aquinas’ argument, it looks like that argument, strictly speaking, only can be taken to show that there is at least one God, not that there is exactly one. So it (perhaps) proves the truth of theism, but not the truth of monotheism. But there’s another, more serious worry about premise (5): it is just not obvious that it’s true that if there is an uncaused cause of things, that that thing would be God. Consider, for example, the following (obviously, oversimplified) statement of Big Bang theory of the origins of the universe: The first event in the history of the universe was an explosion of a an extremely dense collection of particles, with every particle moving apart from every other particle. This event had no cause -- in particular, no intelligent being set it into motion -- and, further, every subsequent event has been an effect of this event. This is a description of the way that the universe could be, according to which there is a cause of the existence of things which was not itself caused to occur. But would it be reasonable to say that, if this picture of the universe is true, God exists? It seems not. After all, if this view were correct, what would God be -- the event of the Big Bang? The condensed matter which exploded in the Big Bang? Either way, God would no longer exist. Moreover, these things lack too many of the attributes central to our conception of God -- such as, for example, personhood, intelligence, love, and moral goodness.