1. Scientists Have Abandoned the Search for Rigid Demarcation Criteria Such as Those Pennock Employs

In response to the affirmative case for intelligent design, critics of design theory frequently claim, as Pennock does, that the very notion of “intelligent design” is inherently unscientific—that design theory does not qualify as science according to established definitions of the term. To justify this claim critics often cite various definitional or demarcation criteria that purport to define science and distinguish it from pseudoscience, metaphysics, or religion.[75] These kinds of arguments have previously played an important role in deciding the scientific, and consequently legal, status of “creation science.” (Moreover, Pennock uses them to cast doubt on the scientific status of the theory of intelligent design, which Pennock mistakenly equates with “creationism,” by his repeated use of the pejorative term, “intelligent design creationism.” I have elsewhere explained why these two theories are not the same—in content, method, and for purposes of the law.[76]) In any case, attempts to define science normatively by reference to rigid demarcation criteria (of the kind that Pennock employs) have failed within the philosophy of science, the relevant discipline for adjudicating questions about the nature and definition of science.

Demarcation arguments made their first appearance in federal court in 1982, when a federal judge adopted a five-point definition of science as part of his finding that a law requiring Arkansas public schools to teach “creation science” alongside standard neo-Darwinian theory was unconstitutional.[77] While, as noted, there are decisive differences between the theory of intelligent design and creation science, critics of design theory often rely upon the McLean criteria[78] to establish definitional or methodological norms in an attempt to disqualify the theory of intelligent design from consideration as a scientific theory.

In McLean, Judge William Overton ruled that an Arkansas law requiring the teaching of “creation science” in public schools violated the First Amendment’s establishment clause.[79] He based his decision not only on the Establishment Clause, but upon a finding that so-called “creation science” does not qualify as science.[80] Indeed, he reasoned that because creation science does not qualify as science it constituted religion.[81] In making his determination, Judge Overton relied upon the expert testimony of the Darwinian philosopher of science Michael Ruse.[82] In his expert testimony, Ruse and other expert witnesses asserted a five-point definition of science that provided allegedly normative criteria for determining whether a theory qualifies as scientific.[83] Any theory, according to Ruse, which failed to meet these five criteria could not be considered to be “scientific.”[84] According to Ruse, for a theory to be scientific it must be:

(1) guided by natural law;
(2) explanatory by natural law;
(3) testable against the empirical world;
(4) tentative in its conclusions; and
(5) falsifiable.[85]

Ruse further testified that creation science—in part because it invoked the singular action of a creator as the cause of certain events in the history of life—could never meet these criteria.[86] Thus, he concluded that creationism might be true, but it could never qualify as science.[87] Judge Overton ultimately agreed, adopting Ruse’s five demarcation criteria as part of his opinion.[88]

Although the case was in some ways superseded by the subsequent ruling of the United States Supreme Court in Edwards v. Aguillard,[89] the McLean case, and the philosophy of science that underwrites it, poses an implied challenge to the scientific status of all theories of origin (including the theory of intelligent design) that invoke singular, intelligent causes as opposed to strictly material causes.[90]

Notwithstanding the favorable reception that Michael Ruse enjoyed in Judge Overton’s courtroom, many prominent philosophers of science, including Larry Laudan and Philip Quinn[91] (neither of whom supported creation science’s empirical claims), soon repudiated Ruse’s testimony on the grounds that, as Laudan argued, it “canoniz[ed] a false stereotype of what science is and how it works.”[92] These philosophers of science insisted that Ruse’s testimony seriously misrepresented contemporary thinking in the philosophy of science about the status of the demarcation problem.[93] Indeed, it now seems clear for several reasons that the philosophy of science provides no grounds for disqualifying non-materialistic alternatives (in particular the theory of intelligent design) to Darwinism as inherently “unscientific.”

First, as Laudan noted, many philosophers of science have generally abandoned attempts to define science by reference to abstract demarcation criteria.[94] Indeed, they have found it notoriously difficult to define science generally via the kind of rigid methodological criteria that Ruse and the court promulgated in the McLean case—in part because proposed demarcation criteria have inevitably fallen prey to death by counterexample.[95] Well established scientific theories often lack some of the presumably necessary features of true science (e.g., falsifiability, observability, repeatability, use of law-like explanation, etc.), while many poorly supported, disreputable, or “crank” ideas often meet some of these same criteria.

Consider, for example, the criteria of falsifiability and tentativeness, two key and related litmus tests in the 1981 McLean trial.[96] Although Ruse asserts that all truly scientific theories are held tentatively by their proponents and are readily falsifiable by contradictory evidence, the history of science tells a very different story. As Imre Lakatos, one of the premier historians and philosophers of science of the twentieth century, showed in the 1970s, some of the most powerful scientific theories have been constructed by those who stubbornly refused to reject their theories in the face of anomalous data.[97] For example, on the basis of his theory of universal gravitation, Sir Isaac Newton made a number of predictions about the position of planets that did not materialize.[98] Nevertheless, rather than rejecting the notion of universal gravitation he refined his “auxiliary assumptions” (e.g., the assumption that planets are perfectly spherical and influenced only by gravitational force) and left his core theory in place.[99] As Lakatos showed, the explanatory flexibility of Newton’s theory in the face of apparently falsifying evidence turned out to be one of its greatest strengths.[100] Such flexibility emphatically did not compromise universal gravitation’s “scientific status” as Ruse’s definition of science would imply.[101]

On the other hand, the history of science is littered with the remains of failed theories that have been falsified, not by the air-tight disproof of a single anomaly, but by the judgment of the scientific community concerning the preponderance of data.[102] Are such falsified, and therefore falsifiable, theories (e.g., the flat earth, phlogiston, geocentricism, flood geology, etc.) more scientific than successful theories (such as Newton’s was in, say, 1750) that possess wide-ranging explanatory power?

As a result of such contradictions, most contemporary philosophers of science have come to regard the question, “what distinguishes science from non-science,” as both intractable and uninteresting. Instead, philosophers of science have increasingly realized that the real issue is not whether a theory is “scientific” according to some abstract definition, but whether a theory is true, or warranted by the evidence. As Laudan explains, “If we would stand up and be counted on the side of reason, we ought to drop terms like ‘pseudo-science’ . . . they . . . do only emotive work for us.”[103] As Martin Eger has summarized, “[d]emarcation arguments have collapsed. Philosophers of science don’t hold them anymore. They may still enjoy acceptance in the popular world, but that’s a different world.”[104]

2. Specific Demarcation Criteria Applied to the Origins Question Fail to Distinguish Design from Its Competitors

Even if one assumes for the sake of argument that criteria could be found to demarcate science in general from non-science in general, the specific demarcation criteria used by Ruse in the McLean case (and by others) have proven utterly incapable of discriminating the scientific status of materialistic and non-materialistic origins theories.[105] Laudan noted, for example, that Judge Overton’s opinion made much of creation science’s inability to be tested or falsified.[106] Yet, as Laudan argues, the claim that:

Creationism is neither falsifiable nor testable is to assert that Creationism makes no empirical assertions whatever. That is surely false. Creationists make a wide range of testable assertions about matters of fact. Thus, as Judge Overton himself grants (apparently without seeing its implications), the creationists say that the earth is of very recent origin . . . they argue that most of the geological features of the earth’s surface are diluvial in character . . . they assert the limited variability of species. They are committed to the view that, since animals and man were created at the same time, the human fossil record must be paleontologically co-extensive with the record of lower animals.[107]

Laudan notes that, though creation scientists “are committed to a large number of factual . . . claims,” available evidence contradicts their empirical claims.[108] As he explains, “no one has shown how to reconcile such claims with the available evidence—evidence which speaks persuasively to a long earth history, among other things. In brief, these claims are testable, they have been tested, and they have failed those tests.”[109]

Yet, Laudan notes, if creationist arguments have been shown false by empirical evidence (as Ruse and other expert witnesses at the Arkansas trial no doubt believed), then creation science must be falsifiable.[110] But if it is falsifiable, then by Ruse’s own criterion, it must qualify as scientific.

Similar problems have afflicted other demarcation criteria. For example, insofar as both creationist and evolutionary theories make historical claims about past causal events, both theories offer causal explanations that are not explained by natural law. The theory of common descent, a central thesis of the Origin of Species, does not explain by natural law. Common descent explains by postulating hypothetical historical events (and a pattern of events) which, if actual, would explain a variety of presently observed data.[111] The theory of common descent makes claims about what happened in the past—namely that unobserved transitional organisms existed—forming a genealogical bridge between presently existing life forms.[112] Thus, on the theory of common descent, a postulated pattern of events, not a law, does the main explanatory work. Similarly, as Laudan notes, scientists often make “existence claims” about past events or present processes without knowing thenatural laws on which they depend.[113] As he notes, “Darwin took himself to have established the existence of [the mechanism of] natural selection almost a half century before geneticists were ableto lay out the laws of heredity on which natural selection depended.”[114] Thus, Ruse’s second demarcation criterion would require, if applied consistently, classifying both creation science and classical Darwinism (as well as much of neo-Darwinism) as unscientific. As Laudan notes,

If we took the McLean Opinion criterion seriously, we should have to say that. . . Darwin [was] unscientific; and, to take an example from our own time, it would follow that plate tectonics is unscientific because we have not yet identified the laws of physics and chemistry which account for the dynamics of crustal motion.[115]

Third, analyses of the demarcation problem have suggested that naturalistic and nonnaturalistic origins theories (including both Darwinism and design theory) are “methodologically equivalent,” both in their ability to meet various demarcation criteria and as historical theories of origin. As noted above, Laudan’s critique suggests that when the specific demarcation criteria promulgated in the McLean case are applied rigidly, they disqualify both Darwinism and various non-materialistic alternatives.[116] Yet as his discussion of falsification suggests, if certain criteria are applied more liberally, then both theories may qualify as scientific. My own work on the demarcation issue has confirmed and amplified Laudan’s analysis.[117] I have shown that philosophically neutral criteria do not exist that can define science narrowly enough to disqualify theories of creation or design without also disqualifying Darwinism and/or other materialistic evolutionary theories on identical grounds.[118] Either science will be defined so narrowly as to disqualify both types of theory, or science must be defined more broadly, and the initial reasons for excluding opposing theories will evaporate. Thus, materialistic and non-materialistic origins theories appear to be methodologically equivalent with respect to a wide range of demarcation criteria—that is, both appear equally scientific or equally unscientific provided the same methodological criteria are used to adjudicate their scientific status (and provided philosophically neutral criteria are used to make such assessments).

Indeed, recent work on the historical sciences suggests deep methodological and logical similarities between various origins theories. Philosopher of biology Elliot Sober has argued that both classical design arguments and the Darwinian argument for descent with modification constitute attempts to make inferences to the best explanation.[119] My work in the philosophy of science has shown that both Darwinism and design theory attempt to answer characteristically historical questions: both may have metaphysical implications or overtones; both employ characteristically historical forms of inference, explanation, and testing; and both are subject to similar epistemological limitations.[120]

3. Pennock's Specific Demarcation Criteria Fail to Disqualify the Theory of Intelligent Design

Despite the well-known difficulties with demarcation arguments, Pennock claims that excluding the theory of intelligent design from consideration as a scientific hypothesis “is entirely reasonable” given the methodological requirements of scientific investigation. In his report, Pennock claims specifically that the theory of intelligent design fails to meet a key requirement of the scientific method, namely, testability. He claims the design hypothesis is not testable for three reasons. First, he claims that it is not testable because the theory of intelligent design fails to explain phenomena by reference to observable entities (or, perhaps, because it is not based upon observable evidence—Pennock is not entirely clear). Second, he claims the theory of intelligent design is not testable because it posits an explanation that does not refer to causal laws (or law-like processes) that would allow it to be tested by isolating variables under controlled laboratory conditions. Third, Pennock argues that the theory of intelligent design is not testable because it invokes a supernatural being that could in principle cause any event or situation whatsoever, thus making the design hypothesis consistent with all possible states of affairs and refutable by none.

I will examine each of these three arguments in order.

First, Pennock seems to claim that the unobservable character of a designing intelligence (which he assumes is necessarily supernatural) renders it inaccessible to empirical investigation and thus precludes the possibility of testing the theory of intelligent design. As he explains, “science operates by empirical principles of observational testing; hypotheses must be confirmed or disconfirmed by reference to intersubjectively accessible empirical data.” (p. 20) Or as he puts it, “Scientific models must be judged on the natural grounds of evidence. . .” Pennock denies that the theory of intelligent design meets these criteria. Thus, Pennock conjoins two demarcation criteria: “observability and testability.” Both are asserted as necessary to scientific status, and the converse of one (un-observability) is asserted to preclude the possibility of the other (testability).

It turns out, however, that both parts of this formula fail. First, many scientific theories invoke unobservable entities to explain observable data, as theoretical physics if nothing else has abundantly demonstrated. Forces, fields, atoms and quarks are all unobservable. The postulation of such entities is no less the product of scientific inquiry for that. Similarly, past events, mental states, subsurface geological features and many cellular and molecular structures are unobservable entities. All are, however, inferred from observable phenomena. Most are also unambiguously regarded as part of scientific inquiry.

Further, unobservability does not preclude testability: claims about unobservables are routinely tested in science indirectly against observable phenomena. That is, the existence of unobservable entities is established by testing the explanatory power that would result if a given hypothetical entity (i.e., an unobservable) were accepted as real or operative. This kind of testing usually involves some assessment of the established or theoretically plausible causal powers of a given unobservable entity. In any case, many scientific theories are evaluated indirectly by comparing their explanatory power against the explanatory power of competing hypotheses.

Consider an example. During the race to elucidate the structure of the genetic molecule, both a double helix and a triple helix were considered, since both could explain the photographic images produced via x-ray crystallography.[121] While neither structure could be observed (even indirectly through a microscope), the double helix of Watson and Crick eventually won out because it could explain other observations that the triple helix could not. The inference to one unobservable structure—the double helix—was accepted because it was judged to possess a greater explanatory power than its competitors with respect to a variety of relevant observations. Such attempts to infer to the best explanation, where the explanation presupposes the reality of an unobservable entity, occur frequently in many fields already regarded as scientific, including physics, geology, geophysics, molecular biology, genetics, physical chemistry, cosmology, psychology and, of course, evolutionary biology.

As such, the unobservable character of the intelligence inferred by design theorists does not provide an in principle basis for disqualifying the theory of intelligent design from consideration as a scientific theory. If it did, neo-Darwinism (and all other evolutionary theories) would also fail to qualify as a scientific theory. Indeed, evolutionary theorists have long defended the allegedly unfalsifiable [122] (and untestable) nature of their theoretical claims by reminding critics that many of the creative processes to which they refer occur at rates too slow or (in the case of Stephen J. Gould’s theory of punctuated equilibrium) too fast to observe.

Further, the core historical commitment of evolutionary theory, that present species are related by common ancestry, has an epistemological standing that is very similar to that of the theory of intelligent design. The transitional life forms that ostensibly occupy the nodes on Darwin's branching tree of life are unobservable, just as the postulated past activity of a designing intelligence is unobservable.[123] Transitional life forms are theoretical postulations that make possible evolutionary explanations of present biological data. An unobservable designing agent is, similarly,postulated to explain observable features of the living world such the chemical sequences that store information in DNA, and the miniature machines and complex circuits found in cells. The theory of intelligent design does invoke an unobservable designing intelligence, but it does so to explain observable features of the living world. Moreover, design theorists test and justify their inferences to intelligent design by comparing the explanatory power of the design hypothesis against that of rival hypotheses. Indeed, I have self-consciously applied this method of testing in the papers that I have written making a case for intelligent design as the best explanation of the presence of the biological information in living systems.[124] In so doing, I have followed the standard methodological practice of the historical sciences.

Indeed, Darwin used this indirect method of testing and insisted that standards of direct verification or observation of hypotheses were wholly irrelevant to evaluating theories of origins. As he complained to Joseph Hooker: “I am actually weary of telling people that I do not pretend to adduce direct evidence of one species changing into another, but that I believe that this view in the main is correct because so many phenomena can be thus grouped and explained.”[125] Further, Darwin used precisely the same method of testing—inference to the best explanation—that I and other design theorists have used to evaluate and justify our proposals in our technical scientific work. In a letter to the American biologist Asa Gray he explained how he used this method of comparative hypothesis testing to assess his own theory of common descent:

I . . . test this hypothesis [common descent] by comparison with as many general and pretty well established propositions as I can find—in geographical distribution, geological history, affinities, etc. etc. And it seems to me that, supposing that such a hypothesis were to explain such general propositions, we ought, in accordance with the common way of following all sciences, to admit it until some better hypothesis be found out.[126]

Pennock claims that the theory of intelligent design cannot be tested for a second, though related, reason. He claims the theory of intelligent design is not testable because it does not refer to “causal laws” (or law-like processes) that would allow it to be tested by isolating variables under controlled laboratory conditions. Indeed, he seems to uphold the testing of causal laws in a laboratory setting as the method of scientific testing. As he describes it: “we confirm causal laws by performing controlled experiments in which the hypothesized independent variable is made to vary while all other factors are held constant so that we can observe the effect on the dependent variable.” (p. 21)

Further, he seems to suggest that because only causal laws or law-like processes can be tested by isolating variables, only theories that refer to such processes are scientific. Thus he assumes tacitly that (a) only hypotheses about causal laws can be tested scientifically, and further that (b) the only scientific method of testing hypotheses involves isolating variables under controlled and repeatable laboratory conditions.

Both these assumptions are false. As noted above, scientists not only formulate hypotheses about law-like regularities or causal laws, but they also formulate hypotheses about causal events, including events that may have occurred in the distant past. Theories in the historical sciences often posit such past events or “causal histories” to explain how some entity might have arisen or to explain why we observe certain data or artifacts today. Chemical evolutionary theory and Darwin’s theory of common descent are scientific theories that have precisely this kind of historical character.[127] Both posit a hypothetical series or pattern of past events to explain the origin of living forms and other data that we observe in the present.

Historical scientific explanations postulate events or sequences of events that occurred in the distant past, and which may not reoccur. Thus, historical scientific hypotheses are not tested in the manner Pennock envisions. Certainly, Darwin’s theory of universal common descent was not tested this way. As noted, Darwin used an indirect method of testing known as inference to the best explanation (sometimes called “the method of multiple competing hypotheses”) to test and justify his theory. His theory was not judged by its ability to predict outcomes once certain variables had been fixed. Rather it was tested by comparing its ability to explain a variety of already known biological phenomena (homology, fossil evidence, embryological similarity) against the explanatory power of its main competitors.

Methods of testing that depend upon direct verification or repeated observation of causeeffect relationships under controlled laboratory conditions have little relevance to historical theories generally, or to evolutionary theories in particular. When Pennock implies that to study something scientifically, scientists must perform “controlled experiments in which the hypothesized independent variable is made to vary while all other factors are held constant so that we can observe the effect on the dependent variable,” (p. 21) he sets a standard for science that neither Darwin’s theory of common descent nor any other historical scientific theory can usually meet. Thus, Pennock's characterization of scientific testing if applied consistently, would disqualify not only the theory of intelligent design from consideration as a scientific theory, but also key parts of neo- Darwinism and chemical evolutionary theory as well.

Nevertheless, it is not the case that causal laws play no role in historical scientific inquiry. Instead, our knowledge of causal laws or, at least, our knowledge cause and effect relationships, usually plays a subsidiary role in such historical scientific inquiry. Historical scientists usually use their knowledge of the present cause and effect structure of the world to judge the plausibility of various competing hypotheses about the past. (This is sometimes referred to as uniformitarian reasoning). Those hypotheses that posit causes that are known to have the power to produce an effect in question are judged to be superior to those hypotheses that lack such “causal powers.” Thus, Darwin used knowledge of the cause and effect structure of the world—in particular his understanding of the kind of effects that natural selection could produce if given enough time—to justify his historical theory of universal common descent (with its claim that a vast amount of continuous biological change had occurred in the past).

Interestingly, however, advocates of the theory of intelligent design also use such uniformitarian reasoning. That is, design theorists use knowledge of the cause and effect structure of the world to assess the plausibility of the competing explanations that have been offered for, say, the origin of biological information. In the process, they also refer to “causal laws,” or, at least, to our knowledge of cause and effect relationships. Dembski, for example, has proffered a law of information conservation. It claims, roughly, that large amounts of specified information (or “complex specified information,” as he puts it) do not arise from purely physical and chemical causes or antecedent conditions, but instead only from intelligent causes. Or, as I have argued, we know from experience that large amounts of new information invariably arise from intelligent sources. That is, whenever we observe information-rich systems and we know how such systems arose, invariably intelligence played a role. Or to quote Henry Quastler again: “information habitually arises from conscious activity.”[128] Since, as design theorists argue, intelligence is the only known entity with the causal powers to produce large amounts of functionally specified information, the presence of such information in living systems points strongly to a prior designing intelligence. (We dispute the studies that Kenneth Miller cites in his Report that claim to explain how large amounts of biological information can arise without assistance from a guiding—or programming—intelligence[129]). Thus, contrary to Pennock’s analysis, the theory of intelligent designcan be evaluated and tested. Moreover, it can be tested in exactly the same way as other historical scientific theories, namely, by evaluating the relative causal and explanatory efficacy of the design hypothesis against its competitors (and against our knowledge of the cause and effect structure of the world).

Even so, historical scientific hypotheses are not typically about causal laws (as Pennock implies); instead they posit past causal events. Our knowledge of the cause and effect structure of the world merely enables us to judge and evaluate those hypotheses. Thus, causal laws are not the main or sole focus of historical scientific inquiry. And since laws aren’t the focus of historical scientific theories, they are not the main, or sole, focus of testing such theories either. And for that reason, many important aspects of historical scientific theories—in particular their claims about past events and causes—cannot be tested under controlled laboratory conditions of the kind that Pennock takes to be necessary to scientific practice and status.

Finally, Pennock claims that the theory of intelligent design is untestable because it invokes a supernatural being with unlimited (omnipotent) powers. Since such a being has powers that could be invoked to “explain any result in any situation,” all events are consistent with the actions of such a being, and therefore, no conceivable event could disprove the hypothesis of supernatural or divine action. Pennock's misrepresentation of the theory of intelligent design renders this objection irrelevant. Because a supernatural being with unlimited causal powers could cause any event whatsoever to occur, such a being always remains a possible explanation for any event. But the theory of intelligent design does not claim to detect a supernatural possessing unlimited powers. Nor does it formulate a hypothesis that is consistent with any event or situation whatsoever. Instead, it claims to detect the action of a prior intelligent cause. It does so, design theorists argue, based upon evidence that points unambiguously to an intelligent cause rather than undirected natural processes. Thus, the theory of intelligent design does not merely affirm that intelligence constitutes a possible explanation of certain features of living systems—such as their high information content or irreducible complexity—it argues that intelligent design constitutes the best explanation of these features, based upon what we know about the cause and effect structure of the world. It follows, therefore, that if the cause and effect structure of the world were different from what design theorists claim—for example, if “complex specified information did arise from purely chemical and physical antecedents,” then the contemporary design hypothesis, with its strong claim to be the best (clearly superior) explanation of such phenomena, would be refuted. Similarly, if key indicia of intelligence—such as digital information or irreducibly complex systems—were not present in living systems, the design hypothesis would not stand as the best explanation of living systems and would, in its present strong form at least, be refuted. Thus, Pennock incorrectly portrays the theory of intelligent design as a theory that is insulated from evidentiary refutation. In short, the theory of intelligent design is testable.

4. Further Problems with the Principle of Methodological Naturalism

As we have seen, Pennock claims that excluding consideration of the theory of intelligent design is entirely reasonable given the methodological characteristics of science. In other words, he affirms an extra-evidential principle known as “methodological naturalism.”[130] Methodological naturalism asserts that, as a matter of definition, for a hypothesis, theory, or explanation to qualify as “scientific,” it must invoke only naturalistic or materialistic entities. On that definition, critics say, the intelligent design hypothesis does not qualify as a scientific theory.

As the preceding sections demonstrate, however, methodological naturalism now lacks justification as a normative definition of science. Attempts to justify methodological naturalism—i.e., the a priori exclusion of intelligent design from consideration as a scientific theory— by reference to various demarcation criteria have failed.[131]

There are other problems with asserting methodological naturalism as a normative definition of science.

First, not all scientists have accepted the principle. Newton, for example, made design arguments within his scientific works, most notably in the Principia and in the Opticks.[131a] Louis Aggasiz, a distinguished paleontologist and contemporary of Darwin, also made design arguments within his scientific works. Thus, current defenders of the principle can at best claim that the principle of methodological naturalisms has had normative force only during certain periods of scientific history. But that suggests that methodological norms can change. And, indeed, part of the current debate about the theory of intelligent design is precisely about whether the principle of methodological naturalism should be regarded as normative today. Darwinists say it should remain normative; design theorists dispute this. Thus, critics of intelligent design can’t settle the debate about whether the theory of intelligent design should be permitted as a scientific hypotheses by invoking the principle of methodological naturalism because the principle is itself a large part of what the controversy is about.

Second, treating methodological naturalism as a normative principle for all of science has an intellectually stifling effect on the practice of certain scientific disciplines, especially the historical sciences. In historical biology or origin-of-life research, for example, methodological naturalism artificially restricts inquiry and prevents scientists from seeking some hypotheses that might provide the most likely, best, or causally adequate, explanations. To be a truth-seeking endeavor, the question that historical or evolutionary biology must address is not “Which materialistic scenario seems most adequate?” but rather “What actually caused life to arise on earth and to develop into new forms of life?” Clearly, one possible answer to this question is: “Life was designed by an intelligent agent that existed before the advent of humans.” If one accepts methodological naturalism as normative, however, scientists may never consider the design hypothesis as possibly true. Such an exclusionary logic diminishes the significance of any claim of theoretical superiority for any remaining hypothesis and raises the possibility that the best “scientific” explanation (as defined by methodological naturalism) may not be the best in fact.

As many historians and philosophers of science now recognize, scientific theory-evaluation is an inherently comparative enterprise. Theories that gain acceptance in artificially constrained competitions can claim to be neither “most probably true” nor “most empirically adequate.” At best such theories can be considered the “most probably true or adequate among an artificially limited set of options.” Openness to the design hypothesis would seem necessary, therefore, to any fully rational historical biology—i.e., to one that seeks the truth, “no holds barred.”[132] Conversely, treating methodological naturalism as normative could impede scientific investigation about what actually happened to cause life to arise on earth.

75. “Explanations employing non-naturalistic or supernatural events, whether or not explicit reference is made to a supernatural being, are outside the realm of science and not part of a valid science curriculum.” NATIONAL ACADEMY OF SCIENCE, TEACHING ABOUT EVOLUTION AND THE NATURE OF SCIENCE 127 (1998).

76. For the distinction between intelligent design theory and creation science, see DeWolf, Meyer & DeForrest,
Teaching the Origins Controversy: Science, Or Religion, or Speech? 2000 UTAH LAW REVIEW 39, pp. 93-95.

77. See McLean v. Arkansas Bd. of Educ., 529 F. Supp. 1255, 1267 (E.D. Ark. 1982) (“[T]he essential characteristics of science are: (1) It is guided by natural law; (2) It has to be explanatory by reference to natural law; (3) It is testable against the empirical world; (4) Its conclusions are tentative, i.e., are not necessarily the final word; and (5) It is falsifiable.”).

78. See id.

79. See id. at 125 8, 1264. T he court specifically found that the Arkansas law “was passed with the specific purpose . . . of advancing religion.” Id. at 126 4. This placed the law directly in conflict with the First Amendment’s establishment clause under the Lemon test. See id. For a statute to pass constitutional muster under Lemon it must have a secular legislative purpose, it cannot either advance or inhibit religion, and it must not foster an excessive entanglement between government and religion. See Lemon v. Kurtzman, 403 U.S. 602, 612-13 (1971); Stone v. Graham, 449 U.S. 39, 40 (1980). A violation of any of the prongs of the Lemon test results in a violation of the Establishment Clause. See McLean, 529 F. Supp. at 1258. The court in McLean found that the Arkansas law’s purpose was to advance religion in the public schools in violation of Lemon's first prong. See id. at 1264. The court also found that the Arkansas law would result in an impermissible entanglement with religion, violating the third prong of Lemon. See id. at 1272.

80. See McLean, 529 F. Supp. at 1267-72. The court’s language was unambiguous: “Section 4(a) [of the Arkansas Act] lacks legitimate educational value because ‘creation science=’as defined in that section is simply not science.” Id. See generally Robert M. Gordon, Note, McLean v. Arkansas Board of Education: Finding the Science in “Creation Science,” 77 NW. U. L. REV. 374 passim (1982) (discussing court’s finding that creation science is unscientific).

81. See McLean, 529 F. Supp. at 1272.

82. See id. at 1267.

83. See id.

84. See id. In the court’s words, these five points are the “essential characteristics of science.” Id. at 1267.

85. See id.

86. See id.

87. See id.

88. See id.

89. 482 U.S. 578 (1987).

90. See NATIONAL ACADEMY OF SCIENCE, TEACHING ABOUT EVOLUTION AND THE NATURE OF SCIENCE (1998).

91. See Larry Laudan, Science at the Bar—Causes for Concern, in BUT IS IT SCIENCE? 351, 355 (Michael Ruse ed., 1988) (“It simply will not do for the defenders of science to invoke philosophy of science when it suits them . . . and to dismiss it as ‘arcane’and ‘remote’ when it does not.”); Philip Quinn, The Philosopher of Science as Expert Witness, in BUT IS IT SCIENCE? 367, 384 (Michael Ruse ed., 1988) (criticizing expert testimony in McLean as “fallacious” and not representative of “settled consensus of opinion in the relevant community of scholars”).

92. Laudan, Science, at 355.

93. See id.; Quinn, at 367-85.

94. See Laudan, Science, at 354-55.

95. See id. at 353-54.

96. McLean v. Arkansas Bd. of Educ., 529 F. Supp. 1255 (E.D. Ark. 1982).

97. See Imre Lakatos, Falsification and the Methodology of Scientific Research Programmes, in SCIENTIFIC KNOWLEDGE: BASIC ISSUES IN THE PHILOSOPHY OF SCIENCE 173 (Janet A. Kouvray ed., 1987) (presenting scientific progress as rational process rather than religious conversions).

98. See id.

99. See id. at 175.

100. See id. at 192.

101. See Lakatos, Falsification, at 175.

102. See id. passim.

103. Larry Laudan, The Demise of the Demarcation Problem, in BUT IS IT SCIENCE? 337, 349 (Michael Ruse ed., 1988).

104. John Buell, Broaden Science Curriculum, DALLAS MORNING NEWS, March 10, 1989, at A21 (quoting unidentified “authority”).

105. See Laudan, Science, at 354.

106. See id. at 352.

107. Id.

108. Id.

109. Id.

110. See id. at 352-53.

111. See CHARLES DARWIN, ON THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION 411-34 (photoreprint, Harvard Univ. Press 1964) (1859).

112. See id.

113. Laudan, Science, at 354.

114. Id.

115. Id.

116. See id.

117. See, e.g., Stephen C. Meyer, The Demarcation of Science and Religion, in THE HISTORY OF SCIENCE AND RELIGION IN THE WESTERN TRADITION: AN ENCYCLOPEDIA 17, 22 (Gary Ferngren et al., eds., 2000) (“[I]nsofar as both creationist and evolutionary theories constitute historical theories about past causal events, neither explains exclusively by reference to natural law.”); Stephen C. Meyer, The Nature of Historical Science and the Demarcation of Design and Descent, in 4 FACETS OF FAITH AND SCIENCE 91 (Jitse M. van der Meer ed., 1996) [hereinafter Meyer, Demarcation]; Stephen C. Meyer, The Methodological Equivalence of Design & Descent: Can There Be a Scientific “Theory of Creation?”, in THE CREATION HYPOTHESIS: SCIENTIFIC EVIDENCE FOR AN INTELLIGENT DESIGNER 67, 102 (J.P. Moreland ed., 1994) (“The exclusion of one of the logically possible programs of origins research by assumption . . . seriously diminishes the significance of any claim to theoretical superiority by advocates of a remaining group.”).

118. See Laudan, Science, at 354.

119. See ELLIOTT SOBER, PHILOSOPHY OF BIOLOGY 27, 56 (1993) (finding that creationism and Darwinism both use characteristic approaches and techniques to attempt to explain certain phenomena).

120. See Meyer, Demarcation, at 91-130; Meyer, Equivalence, at 99 (“[T]he conjunction of the methodological equivalence of design and descent and the existence of a convention that regards descent as scientific implies that design should—by that same convention—be regarded as scientific too.”).

121. H. Judson, The Eighth Day of Creation (New York: Simon and Schuster, 1979), pp. 157-90.

122. The celebrated philosopher of science Karl Popper, applying his falsifiability criterion for scientific theories, concluded in 1976 that “Darwinism is not a testable scientific theory, but a metaphysical research programme.” KARL POPPER, UNENDED QUEST (Glasgow: Fontana, Collins. 1976), p.151. Later he softened his judgment under pressure.

123. Stephen C. Meyer, “Of Clues and Causes: A Methodological Interpretation of Origin of Life Studies” (Ph.D. dissertation, Cambridge University, 1991), p. 120; DARWIN, ORIGIN OF SPECIES, p. 398; D. HULL, DARWIN AND HIS CRITICS (Chicago: University of Chicago Press, 1973), p. 45.

124. S.C. Meyer, The Origin of Biological Information and the Higher Taxonomic Categories, PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON, 117(2) (2004): 213-239.; Stephen C. Meyer, DNA and the Origin of Life: Information, Specification and Explanation, in DARWINISM, DESIGN AND PUBLIC EDUCATION (Michigan State University Press, Meyer and Campbell, eds., 2003).

125. C. Darwin, More Letters of Charles Darwin, ed. F. Darwin, 2 vols. (London: Murray, 1903), 1:184 (emphasis added).

126. Francis Darwin, ed., LIFE AND LETTERS OF CHARLES DARWIN, 2 viols. (London: D. Appleton, 1896), 1:437. (emphasis added).

127. Stephen C. Meyer, “Of Clues and Causes,” pp. 77-136, 169-225.

128. HENRY QUASTLER, THE EMERGENCE OF BIOLOGICAL ORGANIZATION (1964), at 16.

129. Schneider, T.D ., Evolution of Biological Information NUCLEIC ACIDS RESEARCH, vol. 28: 2794-2799
(2000); Lenski, R. E., et al., The Evolutionary Origin of Complex Features, NATURE 423:139-144 (2003).

130. M. Ruse, “McLean v. Arkansas: Witness Testimony Sheet,” in M . Ruse, ed., But Is It Science? (Amherst,
N.Y.: Prometheus Books, 1988), p. 103; Stephen C. Meyer, “The Scientific Status of Intelligent Design: The
Methodological Equivalence of Naturalistic and Non-naturalistic Origins Theories,” in Science and Evidence for
Design in the Universe, ed. Behe, Dembski, Meyer (Ignatius Press, 2000), pp. 151-211.

131. Meyer, “Scientific Status”; L. Laudan, “The Demise of the Demarcation Problem,” in M. Ruse, ed., But Is It Science? pp. 337-50; L. Laudan, “Science at the Bar—Causes for Concern,” in Ruse, ibid., pp. 351-55; A. Plantinga, “Methodological Naturalism?” Origins and Design 18 (1) (1986): 18-26; A. Plantinga, “Methodological Naturalism?” Origins and Design 18 (2) (1986): 22-34.

131a. See footnote 73.

132. P. Bridgman, Reflections of a Physicist, 2nd ed. (New York: Philosophical Library, 1955), p. 535.

133. DeWolf, Meyer & DeForrest, Teaching the Origins Controversy: Science, Or Religion, or Speech? 2000 UTAH LAW REVIEW 39