Although the Argument from Design is, by general agreement in the philosophical community, the weakest of the so-called "proofs for the existence of God," it is far and away the most popular. It was the particular favorite of English divines such as William Paley, whose Natural Theology had a great vogue in the early nineteenth century. The fittingness of means to ends, the arrangement of natural things for human purposes, was said to bespeak the existence of a purposeful Creator as surely as would a watch, found on a deserted beach, indicate the existence of a watchmaker.
Of all God's contrivences, none was thought so patently to belie the heretical doctrine of Evolution as the human eye. How could this extraordinarily complex organ, with its highly specialised cells and precise arrangement of components, have evolved by minute stages in the supposedly distant past? What good, pious critics of Darwin asked with a sneer, would half an eye do to a bit of protoplasm gifted with it by a random mutation? Where is the survival value in a retina unattached to an optic nerve, a lens without a cornea?
In my slow but rich reading of Nick Lane's Ascending Life: The Ten Great Inventions of Evolution [see my earlier post], I have just today completed his chapter on sight. Evolutionary microbiologists now know a simply extraordinary amount both about the molecular level workings of the eye and also about the evolution of photosensitivity, leading up to the appearance of genuine eyes. It turns out that the answer to the sneering question is: half an eye is much better than no eye at all. Indeed, a primitive retina unaccompanied by any of the other components of the eye as we know has considerable survival value in some organisms.
There is a fascinating dialectic at work in this seemingly endless struggle between the evolutionary biologists and the Fundamentalist Creationists. The Creationists present a mystery -- whence the eye? -- and the biologists, after brilliant and painstaking research, give a reply at the anatomical level. The Creationists respond -- But whence these anatomical arrangements, so manifestly purposive in their interconnection? After more work, the biologists reply, at the level of structures so tiny as to be visible only with electron microscopy. Look here at these molecules, they say, which interact so as to make sight possible. But, reply the Creationists, how could those molecules have come into existence and been selected for before the entire arrangement necessary for sight was in place? What is the survival value of just those molecules that will turn out to be required for sight? And with yet more work, this time supported by x-ray crystallography, the biologist answers, with ever greater and more precise detail, tracing the evolution back six hundred million years and more with the aid of the analysis of genetic encoding.
The rhetorical questions posed by the Creationists have already been asked by the biologists. But whereas the Creationists treat them as rhetorical questions, flourishes designed to demonstrate the impossibility of any answer save "God did it," the biologists treat those same questions as spurs to research.
There is a rather comical amnesia and irreligiosity in the behavior of the Creationists. Amnesia, because they can never seem to remember that the explanations they are now prepared to accept are precisely the explanations they so recently said could never be given. One can almost hear them saying, "Oh well, sure, we always knew you could explain things at the molecular level, that goes without saying. But it is at the atomic level that you must invoke God." Irreligious, because they seem utterly incapable of seeing God in a rock or a grain of sand, but must instead insist that only in the deepest recesses of the sub-atomic level of the workings of a cell is an appeal to the existence of God required." One wonders whether they have ever read Gerard Manley Hopkins: "Glory be to God for dappled things."
In the end, the failure of the Creationists is a simple failure of imagination. They are incapable of seeing the always unfinished task of science as a glorious challenge, an exciting adventure. The Creationists are worse than stupid. They are boring.
Lane's last chapter is on Death. I do not know now what I will have to say about that.