Science on Purpose

Apparently the debate over Intelligent Design (ID) is not going away. Perhaps that should read, “the debates.” Beyond the debate over human origins and who or what lies behind terrestrial life, lies the question, “What is science?” At least when we are thinking of “culture wars,” defining the terms is tantamount to winning the debate. If God, higher intelligence, or ultimate guiding purpose can figure legitimately in scientific theorizing, one may expect a seismic shift in our science education, our larger culture, and of course our politics. The issues play out across the country and through history, but a recent controversy at Iowa State University puts the crucial ideas on the table perhaps as well as any.

Guillermo Gonzalez is a young, untenured professor of astronomy at ISU whose new book and public lectures have won him notoriety that does not usually go with that territory. His book, The Privileged Planet, carries the subtitle, How our Place in the Cosmos Is Designed for Discovery. As Des Moines Register staff writer Reid Forgrave explains it (August 31, 2005), the subtitle tells the story: Gonzalez thinks that the coincidence of conditions hospitable to intelligent life is so improbable that it cannot be the result of chance, but must result from purpose; intelligence is what this coincidence of necessary conditions is designed for.

Many of Gonzalez’s colleagues wish he would not classify this assertion as science. Modern science at its beginnings abandoned the traditional conception of nature as being moved by purposes, which the philosophers called final causes. These seemed to be neither observable nor subsumable under precise laws. From then on, scientific explanations would only seek for and appeal to observable, measurable regularities and would expect to discover scientific laws, as Newton did with regard to motion. Common sense, for example, may still explain human behavior sensibly as being guided by our intelligence and purposes, but the natural sciences find such explanations too murky to be verifiable. They seek physiological accounts appealing ultimately to chemistry and physics, which achieve precision and ignore purposes.

By the standards of modern science’s dominant self-understanding, therefore, Gonzalez’s critics have a sound argument: The methods of modern science disallow appeals to purposes in explanation; Gonzalez’s book appeals crucially to purposes in its explanation. Therefore, the book is not science.

In response, Gonzalez insists that his theory depends on no religious assumptions. This is perhaps true, but it is beside the point. Apart from a new intellectual revolution as radical as that of the seventeenth century, the common-sense appeal to purposes in explanations just has no place in modern science. This does not mean there are no purposes and no intelligent guidance; I fancy that both are at work in my writing this (or at least the first). But modern science does not rest with purposes as explanations; it enjoins the continuing search for more fundamental, non-purposive explanations of what we call purposes. (If this categorical rejection of hypotheses that may be true seems perverse, consider the courtroom practice of excluding illegally obtained evidence, however enlightening it may be.) If the critics would stop with the claim that “ID goes beyond science,” they would have a good case.

Ironically, ID’s “scientific” critics find it just as hard to stop with science. When Forgrave seeks to identify “a current view among scientists” on the issues at the heart of Gonzalez’s book, he cites the “theory” of the late astronomer Carl Sagan, who argues that we are here “due to random chance” (Forgrave’s words), not on purpose. Sagan himself supports this claim with the observation, “Our planet is a lonely speck in the great enveloping cosmic dark,” and he finds “no hint that help will come from elsewhere to save us from ourselves.”

We may find the vastness of the universe unnerving, but to make an argument against ID out of it requires imagining what sort of universe an intelligent designer would design if there were one.


If science does not speculate on divine purposes, the response of scientists to assertions or denials of purpose must be not atheism or religious agnosticism, but silence.


Sagan apparently thinks a designer would make a smaller universe, or perhaps make us bigger. Or perhaps he would have begun more recently. In any case, to make an argument out of cosmic vastness requires speculation on the plausible intentions of a designer, which is just what modern science seeks to avoid. In short, Sagan’s words may be emotionally powerful, but they offer no evidence to support a scientific “theory,” as Forgrave dignifies it.

The flimsiness of the emotional appeal in Sagan’s words is also apparent in his calling our planet “a lonely speck.” Presumably Sagan means that intelligent life is scarce in the universe, possibly even unique to our planet. Sagan apparently considers that a point for atheism. But if intelligent life were found beyond our solar system, would that count against atheism? Not likely. If intelligent life is found elsewhere, that will argue for the flukiness of intelligent life as apt to arise wherever the right conditions happen to occur. In short, whether or not intelligence is unique to our planet, atheists can’t lose. (Interestingly, Gonzalez says he would not be surprised to learn that ours was the only planet with intelligent life. Would the uniqueness or non-uniqueness of our planet be evidence for anything?)

Sagan is not alone in speculating on what divine purposes would be like. A recent Op-Ed piece in the New York Times (August 28, 2005) by philosopher Daniel Dennett rebutted ID by citing flaws in the design of organisms. Dennett is sure that since the human eye has a blind spot, it can’t be a product of intelligent design. But even if our eyes are thus defective, it is hard to work such defects into an argument unless you think you know what kind of eyes a putative God would want us to have. In other words, Dennett must assume he knows something about what God’s purposes would be. Perhaps he does know, but (to repeat ourselves) such knowledge of purposes has no place in modern science. Like Gonzalez, Dennett depends on a “common sense” premise that modern science does not allow itself.

Gonzalez’s severest critics accuse him of forcing scientific evidence into a religious mold, even perhaps of politicizing science. If he does violence to the evidence, of course, he is doing bad science; let his peers judge that by professional standards. But in fitting evidence into a speculative mold he is guilty of no more than Sagan or Dennett. Thoughtful scientists often feel the need to comment on the broader significance of their findings. If, however, Gonzalez insists on calling his designer-inference scientific, then he is reconceiving science and truly hopes to promote a revolution. In that case he must expect resistance from practitioners of conventional science and anxiety from thinkers who consider the political impact of earlier scientific revolutions. Removing final causes from scientific theory, after all, was not exactly apolitical.

ID’s critics worry that extra-scientific speculation in a scientist’s book offends against what we sometimes call “methodological naturalism.” This is sometimes taken to mean that science or its methods must be at least implicitly atheistic. But reflection on the attempt to exclude speculation on divine purposes shows how easily that hand gets overplayed, as by Sagan and Dennett. If science does not speculate on divine purposes, the response of scientists to assertions or denials of purpose must be not atheism or religious agnosticism, but silence. The human heart may not be satisfied with this conclusion, but perhaps what we call science must be.

If scientists themselves occasionally lapse into a non-scientific attitude, perhaps charity toward all is most becoming. A double standard is operative in a community that applauds atheistic speculation fobbed off as science and then becomes fastidious about methodological purity when the speculation turns theistic. As for judging whether a true revolution is upon us, it will be hard to find a convincing standard at all until the dust settles.

A. Chadwick Ray teaches philosophy at Central College in Pella, Iowa.