In the increasingly heated debate over teaching intelligent design (ID) in public school science classes, a central bone of contention is the nature of science itself. Those pushing ID say that those who rule out the design hypothesis as non-scientific are just wrong about the nature of true science. Writing in the Wichita Eagle, John Calvert, managing director of the Intelligent Design Network, describes the difference between true, objective science, and false, biased science:

One kind of science is completely objective in its goal (‘objective science’). It is purely theoretical and always open to criticism and the need to change its explanations when new evidence arises. It seeks to let the evidence dictate its explanations, not any bias.

This is the way most science is practiced, and this is the way it is explained to the public and to children in public schools. The real distinction between objective science and all religion is that objective science is theoretical, while religion is dogmatic.

The other kind of science is biased in its goal (‘biased science’). Its ultimate goal is to infer only natural or material causes for the origin, existence and operation of all natural events and phenomena…

Biased science is not objective at its core. The technical name for its bias is scientific materialism or methodological naturalism. This bias is the fundamental tenet of nontheistic religions such as secular humanism, atheism, agnosticism and scientism. It conflicts with theistic religion, because it denies its fundamental tenet that life derives from an intelligent cause for a purpose.

True science, we might all agree, has as its goal objectivity, not bias. So Calvert, in claiming objectivity for the sort of science that countenances intelligent design, claims the mantle of the true scientist. On the other hand, he says mainstream scientists who find intelligent design to be non-science aren’t really doing science. Instead, they’re doing scientific materialism or methodological naturalism, illicitly restricting the scope of scientific explanation to rule out the idea that life could be caused by a purposive intelligence.

Note that this is an empirical claim that Calvert makes. Do mainstream scientists have as their goal “to infer only natural and material causes… for all natural events and phenomena”? No, what scientists actually do is seek the best explanation for phenomena according to widely accepted explanatory criteria, none of which invoke the natural/supernatural distinction. These criteria, among which are ontological conservatism, mechanistic transparency, observational support, experimental replicability, predictive success, connection between classes of phenomena, and theoretical productivity, have yielded the most reliable and unifying sorts of knowledge we possess. Science as a method has itself evolved under the selective pressure of the demand for dependable and comprehensive understanding, and these criteria are the winnowed out result. But it does not, and never has, specified in advance of its explanations what’s natural and what’s supernatural.[1]

Instead, what’s happened is that scientific explanations and theories, using ontologically and philosophically neutral methods, have gradually defined what’s natural, as opposed to what’s supernatural. Those entities and regularities that secure a place in scientific descriptions of the world (e.g., molecules, neurons, species, the law of gravity) are part of what we call nature, and those that haven’t yet (e.g., unicorns, clairvoyance, morphogenetic fields, astral bodies) are perforce excluded. So it’s not that science prejudges what’s natural as it proceeds, although in building upon existing scientific knowledge it necessarily invokes natural phenomena. Rather, it constructs our conception of nature by virtue of its explanatory success, expanding the domain of our reliable understanding of the world. And science can consider any candidate hypothesis tendered for evaluation, natural or supernatural, as long as it has at least some content amenable to potential observation or experiment (if it doesn’t, then it can’t be evaluated). As skeptic Michael Shermer put it on a PBS TV special on The Question of God, “the existence of god is an empirical question.” If you can sufficiently specify your god, we can scientifically test for it. If you can’t, then do you really know what you believe in?

Now, Calvert might take issue with this empirical claim about what science is and what scientists do, and point to various declarations by scientists that they are indeed materialists or “methodological naturalists.”[2] But if they are such, it’s only in the benign sense mentioned above, that scientists will first look for explanatory resources within existing science, which is perforce about nature as we currently understand it. This, to repeat, is not to decide in advance what counts as natural according to some philosophical or ideological criterion, but to proceed on the basis of the relatively secure knowledge already in hand about what we call the natural world.

So, if this account of science is true, Calvert et al. can no longer claim that science is biased toward naturalism in the way they suggest, and their case collapses for an “objective” science that would entertain hypotheses empty of testable or observable content. Given that the canon of scientific explanation is philosophically neutral, and that the intelligent design conjecture is indeed empty, ID could only be taught as an object lesson in bad science, as a failed hypothesis.

The last tactic available to those wanting ID to count as viable science is to amend the explanatory criteria that our desire for reliable, unifying knowledge has produced. Imagine that they manage to require, by voter initiative, court decision, or legislation, that science taught in public schools must include among its accepted, viable explanations that phenomena are produced by unspecified agents or intelligences. [note: this happened in Kansas as of December, 2005] Instead of having to understand and apply the theory of natural selection in explaining the body plans of organisms, students could simply cite a designing intelligence about which nothing is known.

As soon as this possibility is broached, its failure as scientific explanation is apparent. The design hypothesis tells us precisely nothing about the processes or mechanisms of creation, and only these can actually explain how the phenomenon in question came to be as it is. Explanations that appeal to unknown, unspecified agencies play no role in science since they produce no reliable knowledge, in fact no knowledge whatsoever. So the mandate that such explanations be part of science would be futile; it would simply be ignored by practicing scientists in favor of explanations involving specifiable processes and mechanisms. And learning it as an explanatory maxim would put students at serious disadvantage in competition for science jobs, and jeopardize their understanding of how the world works. So revising the explanatory requirements of science by fiat must inevitably fail.

There is, finally, no principled reason or practical basis upon which intelligent design could be introduced into the public school science curriculum except as an example of failed science. True, effective science, driven by the human desire to know, predict and control, won’t countenance any elision in our understanding. Science isn’t philosophically biased, nor can intelligent design count as good science. Until independent evidence accrues that establishes the nature and existence of the designer, there's no reason to suppose he exists.

TWC, 3/05, revised 7/09

2. For instance, here’s an excerpt from an interview with Barbara Forrest, co- author with Paul Gross of Creationism’s Trojan Horse: The Wedge of Intelligent Design: “Science, however, is a naturalistic enterprise. Scientists cannot appeal to supernatural explanations because there is neither a methodology for testing them nor an epistemology for knowing the supernatural. Science has a naturalistic methodology, known less controversially as ‘scientific method.’ That simply means that scientists seek natural explanations for natural phenomena. Science also has an epistemology, namely, the use of human sensory faculties to collect empirical data about the world and the use of our rational faculties to draw conclusions and construct explanations of this data. This is the only successful way to do science, and the pragmatic success of this naturalistic methodology is the only reason scientists use it. There is neither a conspiracy by scientists to prohibit “alternative explanations” nor an arbitrary commitment to naturalism, as ID proponents charge. Scientists use this naturalistic methodology because it works. Period.”