This guy is awesome. I'm reading about him in my Philosophy class and I didn't realize that the way I got to a logical conclusion in the belief in God is basically how he states. Perhaps I read this somewhere else - but I don't know.
So here is the part in my text about St. Thomas Aquinas. Enjoy.
About a century and a half after Anselm died, St. Thomas Aquinas (c. 1225 –1274), whom we have discussed in earlier chapters, interpreted Aristotelian philosophy from a Christian perspective. Aristotle, as we have had occasion to mention, emphasized the importance to philosophy of direct observation of nature. In keeping with his empiricist, Aristotelian leanings, Aquinas regarded the ontological argument as invalid. You cannot prove that God exists, he said, merely by considering the word God, as the ontological argument in effect supposes. For that strategy to work, you would have to presume to know God’s essence. The proposition “God exists,” he said, unlike “A square has four sides,” is not self-evident to us mere mortals. Although you can prove God’s existence in several ways, he asserted, you cannot do it just by examining the concept of God. You have to consider what it is about nature that makes it manifest that it requires God as its original cause.
The ways in which the existence of God can be proved are in fact five, according to Aquinas. Although Aquinas’ theological and philosophical writings fill many volumes and cover a vast range of topics, he is most famous for his Five Ways (but some philosophers—discussed later—do not regard Aquinas’ proofs of God as his best philosophy). It would be surprising if you were not already familiarwith one or another of Aquinas’ Five Ways in some version. In any case, they are included as a reading selection at the end of the chapter.
The First Way
The first way to prove that God exists, according to Aquinas, is to consider the fact that natural things are in motion. As we look around the world and survey moving things, it becomes clear that they did not put themselves into motion. But if every moving thing were moved by another moving thing, then there would be no first mover; if no first mover exists, there would be no other mover, and nothing would be in motion. Because things are in motion, a first mover must therefore exist that is moved by no other, and this, of course, is God. We should note here that Aquinas is usually understood as meaning something quite broad by “motion”—something more like change in general—and as including under the concept of movement the coming into, and passing out of, existence. Thus, when he says that things do not put themselves into motion, do not suppose that he thought that you cannot get up out of your chair and walk across the room. He means that things do not just bring themselves into existence.
The Second Way
Aquinas’ second way of proving God’s existence is very similar to the first. In the world of sensible things, nothing causes itself. But if everything were caused by something else, then there would be no first cause, and if no first cause exists, there would be no first effect. In fact, there would be no second, third, or fourth effect, either: if no first cause exists, there would be no effects, period. So we must admit a first cause, to wit, God. (This is a good time to read the box “The Big Bang,” on page 427.) Note that Aquinas did not say anything in either of the first two proofs about things being moved or caused by earlier motions or causes. The various motions and causes he is talking about are simultaneous in time. His argument is not the common one you hear that things must be caused by something earlier, which must be caused by something earlier, and so on, and that because this chain of causes cannot go back infinitely, there must be a first cause, God. In Aquinas’ opinion, there is no philosophical reason that the chain of causes could not go back infinitely. But there cannot be an infinite series of simultaneous causes or movers, he thought.
The Third Way
Aquinas’ third way is easily the most complicated of the Five Ways. Many consider it his finest proof, though Aquinas himself seemed to prefer the first.
Many paraphrases of the third proof are not faithful to what Aquinas actually said, which is essentially this: In nature some things are such that it is possible for them not to exist. Indeed, everything you can lay your hands on belongs to this “need-not-exist” category; whatever it is, despite the fact that it does exist, it need not have existed. Now that which need not exist, said Aquinas, at some time did not exist. Therefore, if everything belongs to this category, then at one time nothing existed, and then it would have been impossible for anything to have begun to exist—and thus even now nothing would exist. Thus, Aquinas reasoned, not everything is such that it need not exist: “There must exist something the existence of which is necessary.”
This is not quite the end of the third proof, however, for Aquinas believed that he had not yet ruled out the possibility that the necessity of this necessary being might be caused by another necessary being, whose necessity might be caused by another, and so on and so on. So, he asserted, “It is impossible to go on to infinity in necessary things which have their necessity caused by another.”
Conclusion: There must be some necessary being that has its own necessity, and this is God.
We said the third way was complicated.
The Fourth and Fifth Ways
Aquinas’ fourth way to prove God is to consider the fact that all natural things possess degrees of goodness, truth, nobility, and all other perfections. Therefore, there must be that which is the source of these perfections, namely, pure goodness and truth, and so on, and this is what we call God.
And the fifth way or proof of God’s existence is predicated on the observation that natural things act for an end or purpose. That is, they function in accordance with a plan or design. Accordingly, an intelligent being exists by which things are directed toward their end, and this intelligent being is God.
Aquinas’ first three proofs of God’s existence are versions of what today is called the cosmological argument. The cosmological argument is actually not one argument but a type of argument. Proponents of arguments of this type think that the existence of contingent things, things that could possibly not have existed, points to the existence of a noncontingent or necessary being, God, as their ultimate cause, creator, ground, energizer, or source of being. Note the difference between the cosmological argument and ontological arguments, which endeavor to establish the existence of God just by considering his nature or analyzing the concept of God, as we saw attempted by Anselm.
Aquinas’ fourth proof, which cites the existence of goodness or good things, is called the moral argument. Here again, the term does not refer to just one argument but, rather, to a type of argument, and, as we will see, some of the “versions” of the moral argument resemble one another only vaguely.
Let’s summarize all of this. Between them, Anselm and Aquinas introduced what have turned out to be the four principal arguments for God’s existence.
• the ontological argument
• the cosmological argument
• the teleological or design argument
• the moral argument
Notice that none of these four arguments rests on any religious assumptions. They should therefore require the assent of every nonreligious person, if they are sound.
To a certain extent, the history of the philosophy of religion is a continuing discussion of various versions and aspects of these four arguments. Therefore, understanding each type of argument provides you with a good grasp of the basics of the philosophy of religion.
Now before we leave Aquinas, we should call your attention to the fact that the distinction we drew at the beginning of this chapter between theology and the philosophy of religion is pretty much the same as the distinction Aquinas drew between theology and philosophy.
According to Aquinas, if your thinking proceeds from principles that are revealed to you in religion and that you accept on religious faith, then your thinking is theological, though he did not often use the word theology. If your reasoning proceeds from what is evident in sensory experience, then your thinking is philosophical.
According to Aquinas, some theological truths, truths of revelation, are such that philosophy could never discover them. For example, philosophy cannot establish that the universe had a beginning and is not eternal. And not everything discovered by philosophy is important for salvation. But philosophy and theology, although separate disciplines, are not incompatible; in fact, they complement each other, he thought (in contrast to some other Christian thinkers who thought that philosophy can lead to religious errors).
From the standpoint of theology, that God exists is a given, a truth that you start out knowing. From the standpoint of philosophy, that God exists is not a given but may be inferred from your experience.
Thus, Aquinas’ proofs of God’s existence are philosophical proofs. They do not depend for their soundness on any religious principles.
(NOTE - If you made it this far, give yourself a hand.)