Aquinas

Aquinas promoted the use of reason in an Aristotelian manner, namely that of 
inference from effects to causes. He criticized the claim made by Anselm of 
Canterbury in the 11th century that we know that God exists simply by 
understanding the concept of God. God is that greater than which nothing can 
be conceived, and it is evident that such a being must exist. 

The following is a transcript from an Australian TV mini-series, "Brides of 
Christ," which is to my knowledge the only dramatization of the ontological 
argument in the mass media. The characters are a teaching nun and her pupils, 
the novitiates at her convent.


Teacher: St. Anselm proved the existence of God in the following way: God, he 
argued, is that than which no greater can be thought. Does anyone not follow 
that? 

[Several novices raise their hands.]

Teacher: Any concept, no matter how great, allows us to infer an identical one 
that does not exist, and the second one is ipso facto the greater. Since God 
must be the greatest thing anyone can think of, He must exist or He wouldn't 
be God.

Novice 1: He wouldn't be anything if He didn't exist, would He, Sister?

Teacher: Are you trying to be funny?

Novice 1: No, Sister. I just didn't understand the argument.

Teacher: Imagine two apples, equally juicy, crisp to the bite, round and firm, 
and of a brilliant green. Identical in every respect except, one exists, and 
the other one doesn't. Which is the greater?

Novice 2: The one that exists.

Teacher: Same goes for God.

Novice 1: That doesn't follow.

Teacher: St. Anselm's thoughts have been good enough for the greatest minds in 
the Church for nearly 900 years.

Novice 1: Well, it's just a game with words. God isn't a Granny Smith.

Teacher: Is that so?

Novice 2: And you're automatically assuming that existence is better than 
non-existence.

Teacher: Would you rather not exist?

Novice 2: You mean right now, or normally?

Teacher: If you want to stay in the Church, you'll have to accept its 
teachings without question, as I do. 

Novice 2: But what if the Church is wrong?

Teacher: What sort of fool would that make me?

Novice 2: I'm sorry, I didn't mean to question you.

Anselm's argument for the existence of God is known as the "ontological" 
argument, where 'ontological' means 'of or pertaining to being.' The basic 
idea of the argument is that the very being, nature, or essence of God implies 
that God exists. In Anselm's original version, it is the having of the concept 
of God that yields knowledge of God's existence. To understand what God is, is 
to acknowledge that God exists. Kant later commented that this argument is not 
at all persuasive, but is invoked only by those who already believe that God 
exists.

According to Anselm, the concept of God is the concept of the being than which 
none greater can be conceived. To understand this concept, we need to be able 
to compare the greatness of concepts. One way to do so (call it greatness of 
scope), is to compare concepts in terms of their inclusiveness. A concept 
which includes more is greater. Thus my concept of a wonderful beach with an 
adjacent golf course is greater than my concept of just the beach. 

But Anselm was working with a less straightforward comparison of concepts. We 
may compare two concepts which are absolutely alike, except that the object of 
one of the two exists, while that of the other does not. In the example from 
the TV script quoted last time, there are two concepts of an apple, equally 
firm, ripe, juicy, green, etc. But one of the two exists, while the other does 
not. That concept whose object exists is the greater.

If this makes sense, then we can compare the concept of a God which exists 
with an identical one, according to which God does not exist. The former is 
greater than the latter. Then the concept of a non-existence of God is not of 
something greater than which none can be conceived. Thus, the concept of God 
includes God's existence.

But Aquinas pointed out that it does not follow from this that God exists. 
Even if the concept of God does include God's existence, all that follows is 
that concept of God is of a certain sort. We cannot think of God without 
thinking of God existing. But this is just a fact about how we can think. It 
does not mean that God must exist.

Aquinas nonetheless believed that God's existence can be demonstrated through 
reason. He endorsed Aristotle's argument for the unmoved mover. To avoid an 
infinite regress of moved movers, there must be a mover which is not itself 
moved. (There are two ways to understand the regress. One is that without the 
unmoved mover, there is no explanation of the fact that something moves now. 
The second is to say that without the unmoved mover, no movement would ever 
begin.)

More generally, Aquinas held that we can infer from features of the world to 
the existence of God. Such arguments are called a posteriori, because they 
come "after the fact" that the world exists in a certain way. Anselm's 
argument, on the other hand, is a priori, depending as it does on our merely 
possessing the conception of God.

A generalization of the unmoved mover argument is that inferring the existence 
of an uncaused cause. What is the cause of the existence of the world as a 
whole? If its cause has a cause, the same question can be asked, to infinity. 
So there is an uncaused cause.

A related argument is from the contingency of the world. The world might or 
might not have existed. Why does it exist rather than not? If it depends on 
something that itself might or might not exist, the same question can be 
asked, to infinity. So there is a necessary being, one for whom it is false 
that it might not have existed.

A final argument (we omit one other one) is from the order in the world. There 
must be, it claims, something ordering the world to account for the adaptation 
of things. This argument has the advantage of introducing intelligence into 
the ultimate being. The conclusion of the other arguments yield nothing which 
suggests that the being it requires is a thinking being.

Nonetheless, Aquinas did not wish to push the conclusions of reason too far. 
Even if we attribute intelligence to God, it bears only a remote resemblance 
to human intelligence. In fact, the attributes of God are only barely known to 
us. We must have faith to supplement reason in these matters.

Aquinas is perhaps the best known, but certainly not the only major 
philosopher of the medieval period. Among the many notable philosophers were 
John Duns Scotus and William of Ockham, who debated the nature of universals, 
carrying on the discussion initiated by Plato (whose works were then lost) and 
continued by Aristotle.

