This is an essay I wrote for my philosophy class.
On Saint Thomas Aquinas's proofs for the existence of God
Among the philosophers of the Middle-Ages there arose the branch of philosophy known as Scholasticism, which attempted to reconcile the Aristotelian world view with Christian dogma. One of the more curious aspects of this movement was the attempt to prove the existence of God by rational means. I call this curious because religion is often thought of as something decidedly irrational, indeed, one of the Church Fathers is said to have stated "Credo quia absurdum est." Even so, the proofs for the existence of the Deity put forth by the most famous and influential of the scholastics, Saint Thomas Aquinas (1225-1274), are included in the official doctrines of the Catholic Church to this day.
One of Thomas's most important proofs is premised on the idea that all movement has a cause. For a body to move, there must be something to cause the movement. As it is clear that there is an abundance of movement in the world, according to Saint Thomas it is clear that some being must have initiated the first movement. It follows that because God is this First Mover, God exists.
The most common critique of this line of argument is that if all movement must be caused by some being, it follows that even God would have to have a mover in order to move. This implies an infinite series of movers. This type of critique is fully justified, even though Saint Thomas himself rejected it as
irrational. Even though our
Western mode of thought seduces us to believe that a definite beginning and end exist, that there is an
alpha and an
omega, I think that in this particular case it is more sensible to think that movement has always existed, and that there is thus no need for a First Mover.
It should be pointed out that even if we accept Saint Thomas's theory about the First Mover, this does not necessarily mean that the Mover is the Christian God. It can be any being capable of movement, even totally different from Thomas's God. By no means does this being need to be omnipotent - the only one of its abilities which can be inferred from Thomas's argument is that it is capable of initiating movement, which isn't very much. If we take the matter a bit further, it becomes apparent that the whole being is unnecessary. Only the event, the movement, is what is needed. This is because the being initiating the first movement is not essential, the movement itself is. To this Saint Thomas would of course say that this first movement would need someone to cause it, but then we could return to our first objection to his theory that even the First Mover needs a mover.
A rather more interesting argument Saint Thomas presents is based on a conception of possibility derived from Aristotle, which was popular among medieval philosophers. Saint Thomas, along with Aristotle, thought that every single possible event occurs at some point in time, or in other words, if an event is possible, it is so in virtue of happening. Therefore, the universe in a way goes through every possible state of affairs from the beginning of time to the end thereof. As all existing things could according to Saint Thomas also not exist, there was once a time when nothing existed. If such a point in time did indeed exist, then it would follow that nothing could be created either, as nothingness cannot become anything by itself. It is however evident, that at least some things exist at the present moment, which means that even in the time when presumably nothing existed, something had to exist in order to create something out of the nothingness. Therefore God had to exist even when nothing else existed to create everything in existence now.
This argument can be criticized by pointing out that the theory of possibilities on which it is based is rather odd, and quite alien to the modern philosopher. This is because it is not logically contradictory to say that some event is possible, even though it never happens. It is possible for me to rise up from my chair right now - sitting and writing instead does not change this. Even if I never rose up from my chair this would not mean that rising from the chair is impossible. The same holds the other way round - if something has happened, it does not mean that it might not have been possible that the event in question had not happened. We cannot change the past, but that does not mean that the past had to unfold the way it did. Even though Bertrand Russell won the Nobel Prize in literature, this does not mean that he had to. It is no use denying Russell's win today, but it does not follow that he was the only possible winner. Russell's win of the prize is not implied in the definition of the Nobel Prize, nor is it an essential part of Russell's definition, as it is nonsensical to assert that Russell would not be Russell had he not won the prize. Of course, there is a very great risk of committing an anachronism here, as the concept of possibility is very much dependent on perspective, and ours differs to a great degree from the medieval one. Perhaps Saint Thomas would view our notion of possibility as at least as odd as we view his. Therefore it is necessary to note that even if we accepted his view of possibility, our critique of the first mover would be valid here also.
Saint Thomas is not content to stop here, however. His next argument is based on the supposition that values and valuations must have an absolute basis. Because we say that something is good or bad, some person noble and wise, these terms must be based on something real. A being that is absolutely noble, wise, and so forth must exist for us to speak of gradations of rank in these characteristics. In other words, if we are to say that A is more noble than B, we have to compare A and B to an 'absolute nobility'. A is more noble than B because A is more similar to the 'absolute nobility' than B.
This is quite a Platonic line of reasoning. Less than perfect things, in other words everything existing in this world, are shadows of something perfect, which is beyond this world. To Plato, these perfections are Ideas, to Saint Thomas, they are a part of God.
I think Saint Thomas is wrong in thinking that we compare an adjective to some maximal manifestation of the adjective. To use an example of his, I think it is possible to say that an object is hot without comparison with an 'absolute hotness'. It is not even necessary to know what the 'absolute hotness' might be; we only need to know that some other object is less warm than the object we call 'hot'.
At the basis of the Platonic theory of Ideas and Thomas's proof is another assumption which I hold to be incorrect. They both take it for granted that our adjectives refer to something in the actual world. However, the word 'noble', for example, is a thoroughly human invention, and would be altogether meaningless outside human society. It is also possible to have different, but still justifiable, definitions of 'noble', which means that the word has no objective basis. This holds for all other adjectives as well, therefore we must reject this proof for the existence of God, too.
The last of Saint Thomas's proofs I am going to discuss is the most interesting and convincing. It is again based on an Aristotelian notion, that of the purposefulness of nature. Aristotle pointed out that animals behave in very sensible ways even though their intelligence can be assumed to be rather limited. For example, several species of birds fly south to escape the cold of winter. They clearly do not have the capacity to reason that this would be a sensible course of action, so how is it possible that in spite of this they behave in this very wise fashion?
The answer Saint Thomas Aquinas gives to this problem is that God makes the birds fly to the south, and all other animals to behave in sensible, life-preserving ways. Before Darwin, this was a very convincing argument. The probability that the animals would act this way by chance is too low. Because of this, biologist Richard Dawkins asserts in his book The Blind Watchmaker that atheism was not a serious philosophical stance before the theory of natural selection, and he is probably right. Darwin has shown, however, that the methods of natural science are sufficient to explicate the seemingly sensible behaviour of animals. Saint Thomas's last argument is therefore also incorrect, but we should not criticize him for it too harshly, because he did not have the scientific knowledge required to understand this question.
BIBLIOGRAPHY
Aquinas, Saint Thomas. Summa Theologica.
Russell, Bertrand. A History of Western Philosophy.
Saarinen, Esa. Länsimaisen filosofian historia huipulta huipulle Sokrateesta Marxiin.