First, let me say that I too have felt quite
keenly the same awe and wonder at the intricacy of life that
gitm talks about. Its part of my religious
faith as a
Unitarian Universalist.
But, there is a problem with his teleological argument for the existence of God. Consider the human appendix. If humans were designed with a purpose, by a creator, with all that that implies, why would there be a useless or vestigial organ in the human physiology? Or, put another way, if evolution's tendency to produce species that are perfectly adapted to their environment is evidence that there is a divine purpose behind evolution, again, why after millions of years of evolution are there so many imperfections?
In fact, these very questions are discussed far more capably than I ever could by one of my favorite philosophers and scientists, Stephen Jay Gould. Dr. Gould argues that the apparent trend towards perfection is an artifact of humans' understandable tendency to focus on the presumed progressive evolutionary history of our own species, while ignoring the evolutionary history of the vast majority of other organisms (they must not be important because they didn't lead to mammals and humans...)
Indeed, the human appendix is the boring, textbook counter-example to the idea that evolution produces optimal (perfect/purposeful) results. Consider:
Why is most DNA permanently inactive?
Why does the human body produce and respond to, at last count, 14 different proteins that trigger angiogenesis (the growth of blood vessels in new tissue), instead of just the one or two that are most effective?
One could of course argue that these lingering imperfections are the exception, and that in time these imperfections will fade away as evolution continues optimizing each species. Gould argues, however, that these imperfections are the rule rather than the exception; that in fact if you look at the full breadth of physiological, DNA, and behavioral evidence, it would be more accurate to say that evolution produces not perfect species, but species that are just good enough.
In Hen's Teeth and Horse's Toes (1994) and elsewhere, Dr. Gould argues that is when you take an unvarnished look at how creatures have evolved, it seems clear that evolution could not have been the result of a Creator:
The second argument -- that the imperfection of nature reveals evolution -- strikes many people as ironic, for they feel that evolution should be most elegantly displayed in the nearly perfect adaptation expressed by some organisms -- the camber of a gull's wing, or butterflies that cannot be seen in ground litter because they mimic leaves so precisely. But perfection could be imposed by a wise creator or evolved by natural selection. Perfection covers the tracks of past history. And past history -- the evidence of descent -- is the mark of evolution.
Evolution lies exposed in the imperfections that record a history of descent. Why should a rat run, a bat fly, a porpoise swim, and I type this essay with structures built of the same bones unless we all inherited them from a common ancestor? An engineer, starting from scratch, could design better limbs in each case. Why should all the large native mammals of Australia be marsupials, unless they descended from a common ancestor isolated on that island continent? Marsupials are far from being ideally suited for Australia; witness how many have been wiped out by placental mammals imported by man from other continents
(Stephen Jay Gould, "Evolution as Fact and Theory," May 1981; from Hen's Teeth and Horse's Toes: Further Reflections in Natural History, New York: W. W. Norton & Company, 1994, pp. 253-262.)
But having (hopefully) punched some holes in the argument that organism's adaptations to their environment are Teleological and evidence of a Creator, I'll now reverse course a bit and admit that I am not an atheist, merely an agnostic. I think there is a lot of evidence in nature for the existence of a higher power of some sort. It is miraculous that there is order of any sort at all, not to mention the level of order required for an organism to be able to write this write-up. Its just that evolutionary biology is not a very good place to look for this perfection.
Rather, one should look at physics. Consider that both gravity and electromagnetism both follow the same inverse-square law, i.e. that the strength of the force is inversely proportional to the square of the distance. Consider too the elegant perfection of equations such as E = mc2. Now its possible we will one day formulate a grand unified theory, that shows gravity and electromagnetism (and the strong and weak nuclear forces) to be in fact one phenomenon. If so, it would support a more atheist view. But current thinking, for example Stephen Hawking, suggests that gravity and the other forces are not manifestations of a single force; instead, Hawking proposes "weak anthropomorphism" (sometimes called the "weak anthropic principle") as the explanation for why gravity and the other forces both obey the inverse-square law, even though they are different, irreducible phenomena.
Weak anthropomorphism is hard to summarize, but I'll try: it states there are a number of different universes that could exist, each with their own set of universal laws. In the set of all possible laws in all possible universes, laws that involve inverse-square relations are common enough that it is likely that a given universe will have more than one law that involves an inverse-square relationship. In other words, we do not need to postulate a extra-natural creator to explain why the laws of unrelated phenomena have certain similarities. One scientific test to support or refute weak anthropomorphism would be something like: use mathematics, especially set theory, to describe the set of all possible universes and their laws and their relations, then count the number of laws that have the inverse-square relation as compared to the ones that don't, on a per universe basis. If weak anthropomorphism is true, the number of universes having few or no inverse-square laws would turn out to be much smaller than the number of unverses having many inverse-square laws.
A similar experiment might be imagined to explain why laws like E = mc2 exist, in other words, to explain why so many fundamental, distinct entities (energy, mass, and the speed of light) turn out to be related in such an elegant way. And so on for all the other amazing examples of elegance we observe in the universe. Hawking hasn't done these experiments, but he believes they can and should be done.
According to Hawking, there are two alternatives to weak anthropomorphism: creation and strong anthropomorphism. For a variety of reasons, creation isn't useful as a scientific theory, as has been discussed more than adequately, elsewhere on E2. Strong anthropomorphism essentially states that the observation that we exist and have observed the inverse-square law in unrelated phenomena, proves that no universe can exist without the inverse-square law. According to Hawking, strong anthropomorphism is a tautology, and therefore is not useful as a scientific theory.
So until Hawking delivers his proof, I think the best example of the Teleological Argument in action is found in physics, not in evolutionary biology.
Fun Gould Quotes:
Dr. Gould provides some colorful examples of why one shouldn't infer purpose or intent from behavior that seems directed towards a goal.
...the most outstanding feature of life’s history is a constant domination by bacteria. In fact, this is not the age of man as the old textbooks used to say, or the age of mammals, or even the age of insects, which is more correct, if you want to honor multicellular animals. This is the age of bacteria. Bacteria have always been dominant.
...
It’s an old statistical paradigm called the drunkard’s walk, which is a wonderful way of illustrating how you can get directional and predictable motion within a totally random system. All right. Here’s the story. A drunk staggers out of a bar. Here’s the bar, and he’s leaning right against the wall of the bar. Now, he’s staggering completely at random, back and forth. There’s a gutter 30 feet away. He staggers five feet every time he staggers, completely at random, goes towards the bar as often as he goes away, except if he hits the bar wall, he can’t go through it, so he just stands there until he staggers away. Now, where does he end up every time? Of course, he ends up in the gutter. He falls down in the gutter, the thing’s over. We understand that very easily.
http://www.pbs.org/newshour/bb/science/gould_11-26.html, Nov. 26, 1996 interview "Spinning Evolution".
The drunk isn't ending up in the gutter by design. When we see a species that appears to evolve towards an end, we shouldn't necessarily infer that this is by design (the creature's or a creator's).
Dr. Gould is fond of interdisciplinary analogies to illustrate his point, in this case, architecture and physiology.
Here's the situation: You decide to build a church by mounting a circular dome on four rounded arches that meet at right angles. I'll accept that as an analog of adaptation; that's an engineering design that works. But once you do that, you have four tapering triangular spaces where any two arches meet at right angles. The spaces are called spandrels or pendentives, but the more general architectural term is spandrels. They're spaces left over.
No one can claim that the spandrels under the dome are adaptations for anything. I suppose it's a good idea to put some plaster there otherwise the rainwater is going to come in but the fact that they're tapering triangular spaces is a side consequence of the adaptive decision to mount the dome on four arches. It's space left over. It's a side consequence; it isn't an adaptation in itself.
http://www.edge.org/documents/ThirdCulture/i-Ch.2.html
These spandrels were side effects of the "evolution" (actually evolution by design, not evolution by natural selection; but we can safely ignore that flaw in the analogy) of church "physiology", they did not initially make the church more useful to its builders, but they didn't hurt either. Later in history, builders began taking advantage of these odd triangular spaces to serve as niches for statuary and the like, thus spandrels became advantageous instead of incidental, without having been purposefully designed as such.
One of the arguments supposedly in favor of the teleological approach is that higher intelligence is a complex emergent property, that isn't very useful unless it appeared simultaneously with communication, tool use, and other things; therefore it is unlikely that all these things could have evolved all at once, without some kind of design. Dr. Gould argues that intelligence may have evolved in a fashion analogous to spandrels; natural selection initially might have favored larger brains and larger neocortexes because they allowed a greater number of stimulus-response associations, or because it was useful to have spare capacity in case of brain damage. Stimulus-response associations are present in a variety of animals and are generally not considered to be intelligence. Emergent properties such as higher order associations (intelligence) were a side effect of this larger neocortex, and remained latent until other prerequisites for intelligence, such as communication and tool use, evolved.
When confronted with the most primitive, ad hoc adaptation, theists will take it as proof of divine benevolence. When confronted with the overwhelming chaos of nature's blind nigh-excretory life-production, they will ignore it. The world looks exactly as we would expect it to look if nobody were at the controls. You can quote me on that.
Well put! But what about that inverse-square relation, eh smarty? Thanks to basic geometry and conservation of angular momentum, the centripetal force required to keep an object in orbit is the inverse-square of the radius. How is it that both gravity and electromagnetism just happen to follow this same relation? If they didn't, the only stable orbit would be a perfect circle, any perturbation and the solar system, or an atom, would fly apart or implode. Even many atheists admit to an overwhelming sense of amazement and wonder at stuff like this.
Stable orbits certainly don't prove that God exists, but clearly, further research is required...
Update April, 2003: Apparently there may be the outlines of a mathematical basis for why certain seemingly unrelated forces follow inverse-square laws, check out Any's Why gravitation is an inverse square force and the stuff at The Inverse Square Law. I still wonder if there mustn't still be a role for some higher power, and my wondering goes like this: sure, we understand the earth is round, the solar system is arranged thus and so, and by applying some equations we can confidently predict the precise moment the sun will rise tomorrow morning. But what causes the scientific principles that held true yesterday to persist in holding true tomorrow? I suppose this is akin to Aristotle's Unmoved Mover idea. Clearly, more research is still required...