Why It's Unconstitutional to Teach "Intelligent Design" in the Public Schools, as an Alternative to Evolution

Last week, the American Civil Liberties Union sued the Dover, Pennsylvania School Board. The ACLU argues that the School Board violated the Constitution's Establishment Clause by mandating that students in public school biology classes be taught the theory of "intelligent design" as an alternative to evolution.

Proponents of intelligent design--which is closely related to what is sometimes called "creationism"--point to gaps in the fossil record and other uncertainties to argue that evolution by natural selection cannot explain the emergence of new species. They contend instead that an intelligent agent must have been guiding the course of life on Earth.

Evolution opponents have recently scored political victories outside Dover, Pennsylvania as well. In Cobb County, Georgia, public school textbooks discussing evolution must now contain a disclaimer warning that evolution is "a theory, not a fact." That policy, too, is the subject of pending litigation.

And the November election returns in Kansas have given critics of evolution a majority on that state's school board. It is only a matter of time until Kansas mandates the teaching of alternatives to evolution.

Yet Supreme Court precedent holds that state-sponsored attacks on evolution in the public schools are unconstitutional. Why, then, are evolution opponents in Dover, Cobb County and Kansas, trying to change curricula? Aren't these efforts doomed to fail once they are challenged in court? Are the evolution opponents engaging in mere symbolic protest?

The surprising answer is: Perhaps not. That is because the leading Supreme Court decision, in the 1987 case of Edwards v. Aguillard, contains an apparent loophole that evolution's critics may hope to exploit.

Aguillard appears to rest on the Justices' finding that the proponents of theories like intelligent design were subjectively motivated by religion. Accordingly, by keeping their religious motivation secret, proponents of the policies in Dover, Cobb County, and elsewhere may hope to evade the Aguillard decision.

However, as I argue below, this evasion should not succeed. Instead, the First Amendment should be construed to bar the mandatory teaching of intelligent design regardless of the purposes expressed by those imposing the mandate.

The Aguillard Decision: Barring Teaching of Creation Science in Public Schools

In the Dover case, the ACLU contends that the "intelligent agent" in intelligent design theory is simply God in disguise, and that the Dover policy therefore amounts to an unconstitutional establishment of religion. At first blush, the Supreme Court's Aguillard decision would appear to support the ACLU's position.

In Aguillard, the high court invalidated a Louisiana law that forbade the teaching of evolution in public school unless "creation science" was taught alongside it as an alternative. There, as in Dover, the law made no express reference to God or to any religion. Yet the Justices nonetheless found that its purpose "was to restructure the science curriculum to conform with a particular religious viewpoint."

How did the Court know that was the purpose of the Louisiana law? Justice Brennan's opinion looked at two sorts of evidence. First, and unproblematically, it examined the law's actual requirements, to show that the law did not further "academic freedom," as the law itself stated it was meant to do.

Nothing in Louisiana law had previously barred critical analysis of evolution, the Court observed, and so the actual impact of the law was to narrow, rather than broaden, the curriculum.

But the Court went beyond the objective evidence of what the Louisiana law did, invoking its legislative history as further proof that it was impermissibly designed to advance religion. In particular, Justice Brennan's opinion focused attention on the expressed views of the law's principal sponsor.

The Potential Loophole in Aguillard: The Role of Subjective Motive

Justice Scalia, joined by Chief Justice Rehnquist, dissented from the Aguillard ruling. These Justices took special exception to the majority's reliance on evidence of the subjective motives of the legislators who enacted the Louisiana law. In their view, the "purpose" of the Louisiana legislature in enacting the challenged law was necessarily a fiction--a composite of the multiple and mixed motives of the many people composing the legislature.

Justice Scalia's seemingly categorical criticism of any constitutional inquiry into subjective purpose was somewhat overstated. There are other areas of the law in which even Justice Scalia himself accepts that subjective legislative purpose holds the key to a law's constitutionality. For example, under the Court's Equal Protection doctrine, a law that has a disproportionate negative impact on a racial group will be held invalid if, but only if, the law was adopted for the subjective purpose of disadvantaging members of the racial group. To my knowledge, neither Justice Scalia nor Chief Justice Rehnquist has disavowed or even criticized this principle.

Nonetheless, the broader point of Justice Scalia's Aguillard dissent is valid. Legislative purpose is something that courts construct, rather than simply find.

Furthermore, clever legislators can readily evade a constitutional rule that depends on finding evidence of an illicit purpose. The legislators merely need to watch what they say in favor of the bill, expressly relying only on permissible factors.

Whether the members of the Dover School Board were sufficiently disciplined to survive scrutiny of their motives remains to be seen. But the broader lesson that foes of evolution should take from Aguillard is clear: Strictly avoid any reference to religion in your arguments for the laws you seek to enact, even if you secretly favor these laws on religious grounds.

How to Close the Aguillard Loophole

Nonetheless, if Aguillard is interpreted sensibly, even such a strategy of referring only to secular arguments should fail. After all, Justice Brennan's opinion in Aguillard does not state that the Louisiana law would have been valid if only its sponsor had not slipped in acknowledging a religious motive.

Indeed, as Justice Scalia noted, the law's sponsor "repeatedly and vehemently denied that his purpose was to advance a particular religious doctrine." The sponsor's statements quoted by Justice Brennan merely showed that his true aim was not to increase the diversity of biological viewpoints taught in the Louisiana schools.

Thus, the better reading of the Aguillard opinion makes the constitutionality of a law challenged on Establishment Clause grounds depend on its objective purpose--the purpose or purposes that a reasonable person would attribute to the legislature, in light of what the law actually requires. Justice Brennan's opinion saw through the sponsor's stated aim, to his true aim. In the Dover case and other litigation involving intelligent design, the courts ought to be able to do the same.

Discerning the Objective Purpose of the Dover Policy: Why it Matters Whether Intelligent Design is a Scientific Theory

But how should courts go about attributing a purpose to the proponents of laws mandating the teaching of intelligent design? The obvious answer is to ask whether intelligent design is a valid scientific theory.

To be clear, there is no general constitutional requirement that public school students be taught the truth. For example, suppose a school board mandates that high school American history courses emphasize inspiring moments from our past--entirely omitting the shameful treatment of Native Americans, the enslavement of millions of African Americans, and the internment of Japanese Americans. Certainly, the school board would thereby do its students and the community a disservice, but it would not violate any provision of the Constitution with its highly selective history classes.

Nor is science, or even evolution, different. In the old Soviet Union, children were taught Lamarck's view that acquired characteristics are inherited by the next generation--long after that view, as a matter of science, had been discredited. Why? For a political reason: That biological theory fit nicely with Communist ideology about the malleability of man and the natural world. Suppose, for whatever reason, that a contemporary American school board wished to handicap its students by teaching them Lamarckian rather than Darwinian evolution. The Constitution would be no obstacle to such a foolish policy.

But given the social reality, "intelligent design" is different. It is an allegedly scientific theory that bears a striking resemblance to religious views. When the government mandates that students be taught such a theory, courts are rightly suspicious.

At that point, a court should ask whether intelligent design is, in fact, a scientific theory at all. It should do so, not because of any general obligation on the part of schools to teach science correctly, but simply because if intelligent design is not science, then the inference is almost inescapable that the state is impermissibly acting for the purpose of fostering a religious viewpoint.

Is Intelligent Design a Scientific Theory?

Thus we come to the crucial question: Is intelligent design a scientific theory? If by intelligent design, one means the Biblical account of God's creation of the world in six days, the answer is clearly no. Science is based on empirical observation rather than acceptance of divinely revealed truth.

However, most versions of intelligent design offered as alternatives to Darwinian evolution do not insist on the literal truth of the book of Genesis. Rather, they contend that gaps in evolutionary theory can only be plugged by the assumption that an intelligent agent has guided the development of life on Earth.

Some proponents of intelligent design do raise real objections to current understandings of Darwinian evolution. Based on my own reading of the intelligent design literature, it appears that its two strongest arguments point to the general absence of intermediate forms in the fossil record, and to unanswered questions about how certain new, complex patterns of animal bodies could have arisen through random mutation and natural selection.

Nonetheless, for two reasons, it appears that intelligent design is not a scientific theory.

The First Reason Intelligent Design Is Not a Scientific Theory: Conflating Uncertainty with Error

First, insofar as it offers itself as a critique of standard Darwinian evolution, intelligent design cherry-picks uncertainties at the edge of our knowledge, and asserts that these undermine our core understandings. But the fact that some phenomena remain unexplained by natural selection hardly shows that natural selection--which provides a powerful organizing principle for vast swaths of biological data--will not eventually provide the best account of these phenomena.

Consider an analogy. Our best current understanding of gravity remains mysterious because the most ambitious efforts to unify gravity with other forces in the universe--comprising so-called superstring theories or M-theory--have not been empirically tested. Yet that hardly calls into question the principal analytical tools of modern physics.

If the intelligent designers were to apply the same criticisms to physics that they apply to evolution, they would have to say that gravity, too, is "just a theory." However, the fact of Darwinian evolution is as real as the fact of gravity. To be sure, our understanding of each phenomenon is incomplete, but the scientific approach to plugging gaps in our knowledge is not to create a new-anti-theory that dismisses the underlying phenomenon.

The Second Reason Intelligent Design Is Not a Scientific Theory: It Isn't an Explanation

The second problem with intelligent design is even more fundamental: It does not actually explain anything.

Darwinian evolution by natural selection posits a mechanism that explains how species change over time: As environmental conditions change, individual members of a species with traits suited to the new environment survive and reproduce in greater numbers than those lacking the traits. And so, over time, and aided by randomly occurring occasionally adaptive mutations, the species evolves to adapt to the new conditions.

By contrast, what does it mean to say that species arise or change through "intelligent design?" Certainly the term connotes intervention by some intelligent agent. But are the intelligent agent's interventions themselves subject to the laws of the natural world, or are they supernatural?

Even if one is prepared to accept the possibility that science could, without sacrificing its essential premises, include accounts of supernatural phenomena, the concept of "intelligent design," standing alone, is simply a label, not an account.

To press the physics analogy, in classical mechanics, Newton's law of gravity--according to which the attraction between two bodies increases in proportion to the product of their masses and decreases in proportion to the square of their distance--was for many years viewed as problematic, because it described action at a distance. Scientists wondered: How did distant celestial bodies transmit their masses and positions to one another across space, such that they moved instantaneously in reaction?

To a substantial extent, Einstein's theory of general relativity solved the action-at-a-distance puzzle, but suppose that prior to Einstein someone had proposed that gravity worked through the operation of an "intelligent agent." It would have been a perfectly valid objection to this proposal that it isn't an explanation at all, but merely a restatement of the problem. For now, we must ask how the intelligent agent accomplishes action at a distance.

In both biology and physics, in other words, supernatural phenomena may be conceivable. But for an account of such phenomena to qualify as science, it must do more than simply posit an intervention from outside the ordinary natural order. It must also explain how the intervening agent interacts with the natural world. Otherwise, it is simply an article of faith rather than a scientific explanation.

Will Courts Have the Confidence to Declare That Intelligent Design is Not Science?

Accordingly, absent either radical changes in nearly everything we know about biology, or a wholesale reformulation of the tenets of intelligent design, the latter should not be deemed a legitimate scientific theory. And if intelligent design is not science, then it follows that the objective purpose of those who would have it taught alongside evolution in the public schools is to advance a religious view.

Nonetheless, I worry that courts may lack the confidence to declare the mandatory teaching of intelligent design in public schools unconstitutional on the grounds that it is unscientific. As lawyers, most judges lack any serious training in science, and thus may not be comfortable saying what is, and what is not, science.

But the alternative suggested by the Aguillard opinion--of relying simply on the subjective purpose of those who mandate the teaching of so-called alternatives to evolution--is far worse. For while judges can learn enough science to distinguish the real from the fake, they can only ever guess at what legislators are thinking.