Assault on evolution

The religious right takes its best scientific shot at Darwin with "intelligent design" theory.

Published February 28, 2001 5:32PM (EST)

The debate over teaching Darwinian biology in public schools has become the hottest battle in the culture war. The Darwinians cheered their victory on Feb. 14, when the Kansas Board of Education decided -- in a 7-3 vote -- to require the teaching of evolution in public schools across the state, thereby reversing a decision in August 1999 to remove evolution from the statewide guidelines for teaching and testing. But those Darwinians who think that in winning this battle they have won the war are mistaken.

What really happened in Kansas is that the opponents of Darwinism tested a new intellectual weapon. As they become more skilled in the use of that weapon, the tide in this protracted battle could shift in their favor. The new weapon is called "intelligent design theory," or IDT.

Until recently, the critics of Darwinism have championed creationism -- the idea that a literal reading of the early chapters of the Bible offers a more accurate account of human origins than Darwinian biology does. The Darwinians have easily defeated this position by dismissing it as a religious belief unsupported by material evidence and inappropriate in science teaching.

But now intelligent design theorists are claiming that scientific data show evidence in the living world for "irreducible complexity" or "specified complexity," which can only be explained as the work of an intelligent designer. Whether this cosmic designer corresponds to the biblical God, they admit, is a metaphysical or theological question that defies empirical science. Nevertheless, they argue, the observable evidence for design is scientifically compelling.

Steve Abrams, a Kansas school board member who voted with the majority in 1999 and with the minority on Feb. 14, argued vigorously that teaching IDT as an alternative to Darwinism does not depend upon religious belief at all. After the Feb. 14 decision, Abrams insisted that intelligent design is based on "what is observable, measurable, testable, repeatable, falsifiable, good empirical science." The Discovery Institute, which identifies itself as "an intelligent design think tank" in Seattle, issued a press release condemning the decision in Kansas. Its spokesman, Mark Edwards, declared, "What is heralded as the triumph of science is instead a victory for censorship and viewpoint discrimination. This is not what science, or America, is about; discussion of the dissenting scientific opinion on Darwinism should be allowed in science classrooms."

The Discovery Institute is led by conservative Republicans who promote IDT as a strategy for defeating what they regard as the immoral materialism of modern science. They hope to influence the new Bush administration. Their ultimate objective is to win a case before the U.S. Supreme Court that would uphold the constitutionality of teaching IDT in public school biology classes.

The institute's legal strategy is laid out in a recent Utah Law Review article by David DeWolf and Stephen Meyer, who are associated with the organization. Over the past 20 years, the Supreme Court has said that teaching "creation science" in the public schools is an unconstitutional establishment of religion. But the court has also ruled that teaching alternative scientific theories of origins that challenge Darwinian biology is constitutional. And the court has said that when public schools create public forums for the free discussion of ideas, they must not practice "viewpoint discrimination" by suppressing ideas that might have some connection to religion.

DeWolf and Meyer argue that unlike creation science, IDT rests on purely scientific evidence rather than biblical doctrine, and that therefore it represents a scientifically defensible alternative to Darwinism that can and should be taught in the public schools. And although some religious believers will see intelligent design as confirming their religion, DeWolf and Meyer explain, public schools that exclude the teaching of IDT because of this connection to religion are practicing the viewpoint discrimination prohibited by the Supreme Court.

The intelligent design movement was launched by Phillip Johnson with his 1991 book "Darwin on Trial." Johnson is a professor of law at the University of California at Berkeley with a degree from Harvard Law School, and the prestige of his academic background has lent him some credibility. In his book, Johnson metaphorically puts evolution on trial in order to persuade his audience that Darwinism is intellectually bankrupt.

Everyone who has heard Johnson speak publicly -- including his opponents -- acknowledges his rhetorical talents. But defenders of Darwinism have also turned Johnson's strength into a weakness by suggesting that he argues more like a lawyer than a scientist; he relies, they say, on the verbal tricks of the courtroom to win debates in ways that would never be accepted in the scientific community. Moreover, Johnson makes no bones of the fact that his religious beliefs motivate his attack on Darwinism, throwing the scientific validity of his position into question.

Michael Behe, currently IDT's leading proponent, brings greater intellectual respectability to the movement by means of his impeccable credentials. Behe is a real scientist, with a Ph.D. in biochemistry from the University of Pennsylvania. He worked for four years at the National Institutes of Health studying DNA, then became a teacher at Lehigh University in Bethlehem, Pa., where he is now a full professor of biochemistry. Darwinians who debate Behe can't dismiss him as a crackpot or as a smart but deceptive lawyer. And although Behe is a devout Catholic, he never resorts to theological arguments. Instead, he relies on meticulous reasoning, starting from the detailed biochemical processes that he knows so well, to infer that the observable complexity in living things can only be explained by the existence of an "intelligent designer."

The argument for intelligent design has an appealing, common-sensical simplicity. Suppose a particular person, let's say a woman, dies. Was her death just bad luck, an accident? Or was it the inevitable result of some natural cause, such as bone cancer? Or was she murdered? If we can't plausibly explain the woman's death as accidental or necessary, then we must consider the possibility that she was killed intentionally. Similarly, when we see some complex order in nature that can't be explained as the consequence of chance or necessity, we might infer that it has been caused by an intelligent agent. And if we can't reasonably believe the phenomenon to be the work of some naturally intelligent designer (a human being or an animal), then we might choose to see it as the result of a supernaturally intelligent designer.

Behe, and William Dembski, director of the Michael Polanyi Center at Baylor University in Waco, Texas, were the leading speakers on behalf of a Discovery Institute-sponsored conference last year at Baylor. At least half of the speakers -- including some Nobel Prize-winning scientists -- argued against the theory, while Behe summarized the argument of his 1996 book, "Darwin's Black Box," insisting that Darwinian biology cannot explain those biomolecular mechanisms that are "irreducibly complex." A system is irreducibly complex when it consists of many interacting parts that contribute to some function, such that the removal of any one part prevents the whole system from functioning.

The common mousetrap is Behe's favorite example of an irreducibly complex mechanism. It requires at least five parts -- a platform, a spring, a hammer, a catch and a holding bar -- arranged in a specific way. If one part is missing, or if the arrangement is wrong, the mechanism won't function as a mousetrap. We know that such a device did not arise by chance or by some natural necessity. Instead, it was designed by human intelligent agents with the intention of catching rodent pests. Behe suggested that many biological mechanisms show the same purposeful arrangement of parts found in human devices such as the mousetrap; this, he says, points to an intelligent designer outside of nature.

Dembski argued that we should infer intelligent design when we see what he calls "specified complexity." We detect intelligent design in events that are highly improbable (thus complex) and that also correspond to some independently given pattern (thus specified). For example, we might see some Scrabble letters on a table in a sequence such as BDWSFCHJDMB, which would be improbable but not specified. Or we might see a sequence such as THE, which would be specified but not improbable. In neither case could we reasonably infer intelligent design. But we could rightly make a design inference if we saw METHINKSITISLIKEAWEASEL, because this is both improbable and specified; it looks as if some intelligent human being has arranged the letters.

If a detective decides that our deceased woman's death was not accidental or from natural causes but, rather, the result of a murderer's plot, he is inferring intelligent design from specified complexity. According to Dembski, we make similar inferences every day of our lives when we conclude that something has occurred because of someone's purposeful plan.

You can see where Dembski is headed. The genetic information in DNA that governs all life is stored in a highly complex and highly specified sequence of chemicals called nucleotide bases. If God really did create Adam and Eve from the dust of the earth, that would be a miracle. But wouldn't it be equally miraculous if God created the genetic code that controls the development of human beings as well as all other living beings?

Yet the theory of a miracle-working designer seems to lead to more questions than it answers. If evolution doesn't occur, does the designer miraculously intervene to separately create every species of life and every irreducibly complex mechanism in the living world? If so, exactly when, where and how does that happen? Did the designer create the first human beings as fully formed adults, bellybuttons and all? And by what observable causal mechanisms does the designer execute these miraculous acts? How would one formulate falsifiable tests for such a theory? Proponents of IDT refuse to answer such questions, because it puts them at a rhetorical disadvantage. It's far easier for them to take a purely negative position in which they criticize Darwinian theory without defending their own.

Jonathan Wells understands this strategy very well. Like Behe and Dembski, Wells is sponsored by the Discovery Institute to promote IDT as an alternative to Darwinian science. In his new book, "Icons of Evolution," Wells shrewdly employs a purely negative approach -- attacking weaknesses in Darwinian theory while refusing to defend intelligent design in any positive way. He encourages the reader to infer that since Darwinian evolution hasn't been absolutely demonstrated, creation by an intelligent designer wins by default as the only reasonable alternative. However, the standards of proof Wells demands of Darwinian biology are so unreasonably high that he could never satisfy himself if he had to argue for intelligent design.

If we remember nothing else from our biology textbooks, many of us remember what Wells dubs the "icons of evolution," the standard examples used to demonstrate Darwin's theory. These include the peppered moths that became vulnerable to bird predators when they lost their camouflage as a result of air pollution that blackened tree trunks, the various species of finches in the Galápagos Islands that evolved for diverse ecological niches, the similarity between the embryos of radically different species and the pictures showing the gradual evolution of humans from apes. Wells argues that each of these standard textbook stories of evolution and many more are either distortions of the truth or complete lies.

Wells' attack on the story of the peppered moths illustrates how his argument works. Beginning in the 19th century, it was widely noticed in England that the typical peppered moths -- white with dark speckles -- were becoming less common in areas where industrial air pollution had blackened trees, and darker forms of the moth were becoming more common. In the 1950s, Bernard Kettlewell performed experiments in which he released moths with different color patterns and observed the consequences of bird predation, which seemed to show that the darker varieties were less likely to be eaten in areas of industrial pollution, but more likely to be eaten in areas were the air was clear and the trees were covered with light-colored lichens. This became the clearest example of evolution in action, with natural selection favoring changes in the moths that would hide them from predation. Almost every biology textbook now has pictures of peppered moths on tree trunks to show how dark moths are harder to see against dark tree trunks.

The problem with such pictures, however, as Wells indicates, is that they are faked. Peppered moths do not normally rest on tree trunks. These moths fly at night and then hide under the upper branches of trees during the day. The textbook pictures come from scientists who have either placed live moths on tree trunks during the day when the moths become torpid or glued dead moths to tree trunks. Indeed, Kettlewell's experiments are now criticized by researchers as too artificial. Wells accuses biology textbooks of omitting this controversy and thereby concealing the flimsiness of the evidence for Darwinian evolution from students.

Wells does score a good point here in showing how biology textbooks oversimplify -- to the point of distortion -- the evidence for evolution. But to show that the evidence is more complex and more controversial than the textbooks usually indicate is not to show that there is no good evidence at all. The same researchers who criticized Kettlewell's study found that dark moths nevertheless do survive better in polluted, rather than unpolluted, woods, which suggests that they are somehow hidden from bird predators and thus favored by natural selection. One of those researchers concluded "that natural selection, the primary mechanism of evolution put forward by Charles Darwin, actually happens." Wells doesn't quote that.

Darwin never claimed that his theory could be demonstrated with a precision and certainty that would leave no room for reasonable doubt; he believed that no theory of the origin of species could be demonstrated absolutely. He anticipated almost all of the objections to his theory and devoted over one-third of "The Origin of Species" to considering such "difficulties." He admitted that some of the objections "are so serious that to this day I can hardly reflect on them without being in some degree staggered." And yet he insisted that his theory would emerge as highly "probable" to anyone who considered the "facts and arguments" in its favor.

Most of our knowledge in science rests on probability rather than certainty. If the alternative to Darwin's theory of evolution by natural selection is a theory of creation by a miracle-working designer, most of the empirical evidence is still on the side of Darwin. Certainly, no one knows how the existence of a supernatural designer could be rigorously verified by purely scientific means.

Wells is careful to refer to IDT only in passing because he wants to put all the burden of proof on the Darwinians, but he often implies that the only good alternative to Darwinism is "creation by design." And he warns his readers that Darwinism promotes a materialistic view of the world that denies the reality of a spiritual realm. His main conclusion is that "biology students are being taught materialistic philosophy in the guise of empirical science."

This fear of "materialistic philosophy" shows what's really at stake here: At a deeper level, this is a moral, religious and political debate over the adequacy of science in explaining the meaning of human life. For the people at the Discovery Institute, that debate amounts to something like a holy war.

Bruce Chapman, the founder of the Discovery Institute and its president since 1990, is a conservative Republican who held various appointments in Ronald Reagan's administration. He believes that America's moral and religious heart is threatened by the corrosive materialism and atheism of modern scientific naturalism, and he promotes IDT to other conservative Republicans as the only way to win America's culture war. Last May he even sponsored a meeting in Washington for members of Congress, who were given a three-hour briefing on IDT. Now he expects to have some influence in the new presidential administration.

At the briefing, Nancy Pearcey quoted the lyrics of a song by the Bloodhound Gang -- "You and me, baby, ain't nothin' but mammals, so let's do it like they do it on the Discovery Channel." This, she warned, is what we can expect if the materialism of the Darwinians persuades us that we are merely mammals, rather than beings elevated above other animals and created in the image of God. She urged the congressmen in her audience to remember that the U.S. legal system is grounded in the belief in a creator as the ultimate source of moral law. Darwinism, by undermining that belief, is morally and legally dangerous.

American culture has long, if somewhat tensely, maintained a balance among common-sense morality, democratic politics, scientific naturalism and biblical religion, but this kind of rhetoric can make the schisms in American society seem unbridgeable. It's also unwarranted.

Modern science isn't necessarily incompatible with the moral, religious and political traditions of America. Darwin himself believed there was a natural moral sense rooted in the desires of the human animal, and he laid out this biological theory of morality in his 1871 book "The Descent of Man." As intensely social animals, he argued, we need to cooperate with one another to succeed. Natural selection has favored those emotions -- such as love, guilt and anger -- that dispose us to cooperative relationships with relatives, friends and fellow group members. As intellectual animals, we generalize our social emotions into the rules of good conduct and then into moral principles. Our natural moral sense doesn't require religious belief, but it shouldn't surprise us that religious teachings tend to support those universal standards of conduct -- honoring parents, not stealing, refraining from unjustified killing and so on -- that sustain social life.

And while some theologians have dismissed Darwin's theory as atheistic, there's no necessary conflict between Darwinism and religion. Darwin often confessed that scientific research could not answer questions about the First Cause -- the origins of life and the universe -- and as a result left room for religious faith. Many thinkers have seen no contradiction between biblical theology and Darwinian evolution. God could have chosen to create everything in six days. Or he could have chosen to create a universe governed by natural laws in which life would evolve gradually over millions of years. God could also have chosen to allow a moral sense to evolve in human beings. Indeed, there is an old tradition in biblical theology that God implanted a natural moral sense into the animal world. Thomas Aquinas, for example, saw this in the instincts for self-preservation, sexual union, parental care and other social behaviors.

Instead of fighting a dishonest battle for a theory that has little empirical support, American conservatives should welcome the Darwinian idea of morality as rooted in our biology. The idea vindicates the belief held by America's founding fathers that there is a fundamental harmony between scientific knowledge and religious faith. After all, when Thomas Jefferson penned the Declaration of Independence, he seemed to anticipate this very crisis when, in arguing for the existence of the United States, he appealed to "the Laws of Nature and of Nature's God."

By Larry Arnhart

Larry Arnhart is a professor of political science at Northern Illinois University and the author of Darwinian Natural Right: The Biological Ethics of Human Nature.

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