St. Thomas Aquinas discussion

Five Ways to Prove God's Existence

Anselm's Ontological Argument is not acceptable, Aquinas argued, since we are in fact ignorant of the divine essence from which it is presumed to begin. We cannot hope to demonstrate the necessary existence of a being whose true nature we cannot even conceive by direct or positive means. Instead, Aquinas held, we must begin with the sensory experiences we do understand and reason upward from them to their origin in something eternal. In this vein, Aquinas presented his own "Five Ways" to prove the existence of god.

The first three of these ways are all variations of the Cosmological Argument. The first way is an argument from motion, derived fairly directly from Aristotle's Metaphysics:

1. There is something moving.
2. Everything that moves is put into motion by something else.
3. But this series of antecedent movers cannot reach back infinitely.
4. Therefore, there must be a first mover (which is god).

The first premise is firmly rooted in sensory experience, and the second is based on accepted notions about potentiality and actuality. In defence of the third, Aquinas noted that if the series were infinite then there would be no first, and hence no second, or third, etc. The second way has the same structure, but begins from experience of an instance of efficient causation, and the third way relies more heavily upon a distinction between contingent and necessary being.

In all of its forms, the Cosmological Argument is open to serious challenge. Notice that if the second premise is wholly and literally true, then the conclusion must be false. If, on the other hand, it is possible for something to move without being put into motion by another, then why might there not be hundreds of "first movers" instead of only one? Besides, it is by no means obvious that the Aristotelean notions of a "first mover" or "first cause" bear much resemblance to the god of Christianity. So even if the argument succeeded it might be of little use in defence of orthodox religion.

Aquinas's fourth way is a variety of Moral Argument. It begins with the factual claim that we do make judgments about the relative perfection of ordinary things. But the capacity to do so, Aquinas argued, presupposes an absolute standard of perfection to which we compare everything else. This argument relies more heavily on Platonic and Augustinian notions, and has the advantage of defending the existence of god as moral exemplar rather than as abstract intitiator of reality.

The fifth way is the Teleological Argument: the order and arrangement of the natural world (not merely its existence) bespeaks the deliberate design of an intelligent creator. Although it is an argument by analogy which can at best offer only probable reason for believing the truth of its conclusion, this proof offers a concept of god that most fully corresponds to the traditional elements of medieval Christian theology. Since its empirical basis lies in our understanding of the operation of nature, this line of reasoning tends to become more compelling the more thorough our scientific knowledge is advanced.

The Created World

Since the nature of god can be known only analogically by reference to the created world, Aquinas believed it worthwhile to devote great attention to the operation of nature. Here, of course, the basic approach is that of Aristotle, but the commentaries of Ibn Rushd provide a reliable guide as well.

Although we cannot rationally eliminate the possiblity that matter itself is co-eternal with god, Aquinas held, that undifferentiated prime matter can be nothing but pure potentiality in any case. It is only through god's bestowal of a substantial essence upon some portion of prime matter that a real material thing comes into existence. Thus, everything is, in some sense, a hylomorphic composite of matter and form for Aquinas, and god is the creator of all.

But, of course, human beings are a special case. As Aristotle had supposed, the human soul is the formal, efficient, and final cause of the human body. But in this one special instance, Aquinas held that god can add existence directly, without any admixture of prime matter, thus making possible the immortality of disembodied human souls.

Even in this life, Aquinas argued, the intellect is a higher faculty than the will in virtue of its greater degree of independence from the body. As the agent of knowledge, the human intellect comprehends the essences of things directly, making use of sensory information only as the starting-point for its fundamentally rational determinations. Although not all of Aquinas's contemporaries recognized, understood, or accepted this view of human knowledge, it provided ample room for the development of empirical investigations of the material world within the context of traditional Christian doctrine.

"1. There is something moving.
2. Everything that moves is put into motion by something else.
3. But this series of antecedent movers cannot reach back infinitely.
4. Therefore, there must be a first mover (which is god)."

This premise is so obvious (once read, at least) that I cannot believe a physicist could question intelligent design. It's such a big DUH!

"In all of its forms, the Cosmological Argument is open to serious challenge. Notice that if the second premise is wholly and literally true, then the conclusion must be false. If, on the other hand, it is possible for something to move without being put into motion by another, then why might there not be hundreds of "first movers" instead of only one? Besides, it is by no means obvious that the Aristotelean notions of a "first mover" or "first cause" bear much resemblance to the god of Christianity. So even if the argument succeeded it might be of little use in defence of orthodox religion."

I don't see why this argument is of 'little use' in defense of orthodox religion. A first mover must have something by which it gives impetus; where could that come from? Where did the 'first mover' come from and what was it composed of? Without some sort of creation involved, the 'first mover' would not exist. Laws of inertia, perhaps, apply here in some way? (albeit a kind of backwards interpretation...)