Wednesday, March 3, 2010

The Fifth Way

In the Summa Theologiae , St. Thomas Aquinas offers one of the most traditional design arguments in support of God's existence. He writes (with italics):

The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.

In sum, Thomas is arguing as follows:

1. Whatever a) lacks intelligence, b) and acts always, or for the most part, for a certain end, is designed to do so by some intelligence.
2. The laws of nature a) lack intelligence and, b) act always, or for the most part, for a certain end.
3. Therefore, the laws of nature are designed by some intelligence.

The beauty of Thomas' argument is that it runs circles around evolutionary theory. Granted, evolution does take place, but what significance does this fact have for the Fifth Way? Nothing as far as I can see. God may very well choose to use evolution as His means of creating life.

(1) seems quite reasonable. Thomas himself gives the example of an arrow (which lacks intelligence) hitting its mark (end) by the archer (intelligence).

I doubt anyone who takes a realistic view of science and nature will have any reservations about (2). Surely, nature isn't intelligent. If it were, that would be conducive to pantheism. Yet, nature also provides us with many rich regularities, from gravity and electromagnetism, from the strong and weak atomic forces to the sun rising and setting every day, and from the sheer mathematical and logical order of general experience to my breathing. Nature is indeed quite uniform, and don't we have quite the Designer to thank for that!

Now, who designed the Designer? You will notice that this rhetorical question misconstrues the Fifth Way. It's not that whatever acts for an end has a designer, but whatever lacks intelligence and acts for an end has a designer. Those are the two sign-posts of design, and the universe's Designer does not meet the description of lacking intelligence.

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