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While Christoph Cardinal Schönborn and Professor Stephen Barr were arguing over questions of evolution and teleology in the last few issues of First Things , down in Pennsylvania Judge John E. Jones III was deciding Kitzmiller v. Dover Area School District .

The case arose when the Dover school board voted to require that high-school biology teachers read to their students the following disclaimer: “Because Darwin’s theory is a theory, it continues to be tested as new evidence is discovered. The theory is not a fact. Gaps in the theory exist for which there is no evidence . . . . Intelligent Design is an explanation of the origin of life that differs from Darwin’s view. The reference book Of Pandas and People is available for students who might be interested in gaining an understanding of what Intelligent Design actually involves.”

Parents of some students sued, alleging that the board’s policy violated their constitutional rights under the establishment clause. Applying the Supreme Court’s holdings in County of Allegheny v. ACLU and Lemon v. Kurtzman , Judge Jones determined that the policy endorsed a religious message, was motivated by a religious purpose, and had the effect of advancing religion. Since any one of these taken singly would constitute a violation of the establishment clause, the court permanently enjoined enforcement of the school board’s policy. There will be no teaching of Intelligent Design in Dover.

Like others who support the original understanding of the Constitution, I disagree with many of the Supreme Court’s decisions under the establishment clause, but in our system of government a federal-district judge like Judge Jones is bound by those decisions. In applying Allegheny County and Lemon , Judge Jones had to determine whether Intelligent Design is religion or science: If it is religion and not science, then the government’s advancing it would violate the establishment clause.

To the outrage of many Intelligent Design proponents, Judge Jones concluded Intelligent Design is religion and not science. I think he’s half right: Intelligent Design is not science, at least not in the usual sense, but neither is it religion.

To see why, we have to start with neo-Darwinism, the theory that Intelligent Design seeks to replace. In neo-Darwinism, species evolve through random genetic mutations and natural selection. In accordance with the laws of physics, the genes of reproducing organisms are sometimes altered on the molecular level, with the result that offspring have features different from those of their parents. These new features, if they confer an advantage in surviving, will be more likely to be passed on to future generations. Each genetic mutation produces only a very small change in the biological features of the organism, but such small changes accumulate over immense periods of time and lead to the evolution of new species from old.

Intelligent Design poses two distinct challenges to neo-Darwinism. The first is purely negative: Neo-Darwinism is insufficient to explain the existence of certain observed features of organisms. The second is positive: Intelligent Design proposes an alternative theory that purportedly succeeds in explaining what neo-Darwinism cannot.

The argument against neo-Darwinism begins from the undoubted observation that many features of living beings, like the bacterial flagellum or the human eye, are the result of not one genetic mutation but of a large number of such mutations. The Intelligent Design theorist next argues that none of these mutations, taken singly, would confer any survival advantage on the organism: The survival value comes only when all the mutations are present simultaneously. This may or may not be the case. There is significant evidence to suggest that at least some complex features of organisms result from what biologists call exadaptation , a phenomenon in which one genetic mutation confers a certain kind of survival advantage on an organism, and later, after subsequent mutations have occurred, the original mutation combines with the subsequent ones to confer a wholly different advantage. In this way, the mutations necessary to produce complex biological structures could slowly build up over time.

Although most scientists working in the area think exadaptation or similar mechanisms can explain the emergence of complex biological forms, most would probably admit that the issue is not fully settled. Intelligent Design theorists, however, take their objection to be decisive and then advance a new explanation for the existence of complex features of organisms: There is an intelligent designer who intervenes in the process of random genetic mutation and natural selection to cause, simultaneously, a host of genetic mutations needed to produce the observed complex features of organisms. Most Intelligent Design theorists claim to be agnostic about the nature of this intelligent designer, but many will admit privately that they think that the intelligent designer is God.

Even assuming that neo-Darwinism cannot explain the existence of complex biological forms that we observe in the world, does Intelligent Design’s theory that there is an intelligent designer that causes such forms count as science? The answer depends on exactly how we understand science. Judge Jones’ opinion in Kitzmiller goes astray here, for in one sense (which I shall call the Quinean sense, after Harvard philosopher W.V. Quine) we might count as scientific any theory that purports to explain and predict observed phenomena. In his Two Dogmas of Empiricism , Quine wrote,

As an empiricist I continue to think of the conceptual scheme of science as a tool, ultimately, for predicting future experience in light of past experience. Physical objects are conceptually imported into the situation as convenient intermediaries”not by definition in terms of experience, but simply as irreducible posits comparable, epistemologically, to the gods of Homer. For my part I do, qua lay physicist, believe in physical objects and not in Homer’s gods; and I consider it a scientific error to believe otherwise. But in point of epistemological footing the physical objects and the gods differ only in degree and not in kind.

In other words, we posit things unseen in order to explain and predict what we observe. Intelligent Design theorists posit an intelligent designer to explain the existence of certain observed phenomena, and thus Intelligent Design has just as much right to be called science in the Quinean sense as neo-Darwinism does. In this light, the argument between neo-Darwinism and Intelligent Design is a scientific dispute between two competing scientific theories; the dispute is analogous, from an epistemological point of view, to the dispute between Newtonian mechanics and general relativity. The only issue is which theory is best supported by the empirical evidence.

But this Quinean sense of science, while epistemologically important, is a thin one. There is a more robust sense of science in which we require not only that a theory explain and predict phenomena but also that it appeal to lawlike generalizations”to statements that purport to be not only true but necessarily true. For instance, Newton’s Second Law of Motion states that the force acting on a body is directly proportional to its acceleration. This statement is meant as a law of nature: It purports to be true in every case there ever could be. It is the lawlikeness of scientific laws that makes them predictive and so allows them to be falsified by appropriate experiments. When practicing scientists think about science, they generally have in mind this understanding of science: theories that predict and explain observed phenomena by appeal to lawlike generalizations.

We often give explanations for observed phenomena that, while fully justified by the evidence and undoubtedly true, are not couched in lawlike generalizations. In The Hound of the Baskervilles , for example, Sherlock Holmes examines a walking stick and concludes that the owner is a medical doctor, once employed in London but now practicing in the country, under thirty years of age, amiable, unambitious, absent-minded, and the possessor of a favorite dog, larger than a terrier and smaller than a mastiff. Holmes is positing the existence of a certain kind of person to explain observed phenomena (not, as he habitually says, making deductions), but we would not normally call his conclusions science, even when true and convincing. And the reason is that his explanations are not couched in lawlike generalizations.

It is not a law of nature that young doctors who give up practice in the city for a quiet life in the country are unambitious or that everyone who leaves a walking stick in the room of someone on whom he has called is absent-minded. Such statements may be true in general and for the most part, but they admit of exceptions and are not necessary truths. Science in the Quinean sense may make use of such generalizations, and it is a tremendously important human epistemic activity. In fact, almost all of our knowledge is scientific in the Quinean sense; only a small fraction of our knowledge is scientific in the stricter sense. This is not surprising, for clearly the realm of human knowledge is much wider than what we generally think of as science.

The problem with Intelligent Design’s positive explanation positing an intelligent designer is that such a designer would operate not by lawlike necessity but by intelligence and free choice. Explanations that posit intelligent agents to explain observed phenomena are often justified, but they are never scientific in the strict sense, for they do not explain by reference to generalizations that are necessarily true.

That is because the necessity of the scientific law is inconsistent with the freedom of the free agent’s choice. Science explains behavior on the basis of what its objects must necessarily do. Intelligent agents, human or otherwise, make free choices, but these choices flow from the will. Hence, there is no necessity to them, and explanations that appeal to the free choices of intelligent agents”while scientific in the Quinean sense, tremendously important in human knowledge generally, and often justified by the evidence and true in every sense of the word”are not scientific in the sense that physics and chemistry and biology are scientific.

The problem with teaching Intelligent Design in public high schools, therefore, is twofold. First, discussion of Intelligent Design’s argument against neo-Darwinism is out of place in a high-school science classroom because most scientists working in the area do not accept the Intelligent Design criticism of neo-Darwinism and because understanding the scientific issues involves sophisticated arguments far beyond the capacity of nonspecialists, let alone high-school students. Second, even if Intelligent Design’s criticism of neo-Darwinism is warranted, the Intelligent Design theory is not scientific in the strict sense. That is, even if true, Intelligent Design does not belong in a science class.

If Intelligent Design’s proposed explanation of observed phenomena is not science, is it religion? No, at least not in the sense that religion is a revealed doctrine, surpassing human reason and accepted as a matter of faith. That’s not what Intelligent Design is at all, and, to the extent that he held otherwise in Kitzmiller , Judge Jones is mistaken.

The truth is that Intelligent Design is metaphysics, a branch of philosophy. Metaphysics at its best is scientific in the Quinean sense, because it posits things in order to explain the existence of observed phenomena. Aristotle’s arguments about an unmoved mover, Aquinas’ Five Ways, contemporary versions of the cosmological argument in analytic philosophy of religion”all of these are, in the end, proposed explanations of observed phenomena. These arguments seek to explain why there is something and not nothing, usually by positing an extraordinary being causally responsible for the existence of all other beings. To the extent that philosophers have thought of these arguments as proofs or deductions, they are as mistaken as Sherlock Holmes was about his treatment of the walking stick in The Hound of the Baskervilles .

Intelligent Design’s positive thesis is similar to these well-known arguments in metaphysics. It differs primarily in that the phenomena it seeks to explain are much more modest”the existence of complex biological forms rather than the existence of things generally. In one important way, Intelligent Design’s argument is in a much weaker position than traditional cosmological arguments, for empirical results in biology could show that the mechanisms of neo-Darwinism are sufficient to explain the existence of complex biological forms, and in this case the motivation for Intelligent Design’s theory would collapse. It’s much harder to imagine results in physics or other lawlike sciences that could analogously undercut cosmological arguments.

So, if Intelligent Design is not science but still not religion, is Kitzmiller rightly decided? I think so. Like Cardinal Schönborn, I think it is unhelpful to get philosophy mixed up with science. Philosophy should take the results of science as given, as data from which philosophical speculation begins. As Quine wisely said, “No inquiry being possible without some conceptual scheme, we may as well retain and use the best one we know”right down to the latest detail of quantum mechanics, if we know it and it matters.” We ought not inject a philosophical argument into a science class; this is bad epistemology, and it is likely to create confusion. Moreover, scientists are generally as incompetent at philosophy as philosophers are at science. Regardless of how we ought to understand the establishment clause, Intelligent Design does not belong in high-school biology classrooms.

The larger problem the Dover Area School Board was trying to address”the apparent atheistic drift of much public education”may still have a solution, however. I think public high schools ought to offer, at the senior level, a course in philosophy, including metaphysics. The texts should include Aristotle and Aquinas on arguments for the existence of God but also the criticisms of such arguments by Hume and Kant, as well as some contemporary philosophy of religion. This would negate the impression, perhaps created in science classes, that science explains everything there is to explain about the universe.

There’s no doubt that such a class would pass muster under even the Supreme Court’s understanding of the establishment clause. It would also do a lot of good in the world. One thinks that, had he been forced to take such a course in high school, Daniel Dennett”the crusader for biology as the final destroyer of religion”might not say so many foolish things.

Robert T. Miller is an assistant professor at the Villanova University School of Law.