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Intelligent Design is Empirically Testable and Makes Predictions

By Jay Richards and Jonathan Witt

Among the many, many errors in Judge John Jones’ Dover vs. Kitzmiller opinion is the charge that intelligent design (ID) makes no empirically testable claims (see pp. 66 ff.). Similarly, other ID critics assert that intelligent design makes no testable predictions.1 In fact, intelligent design fulfills both criteria since it makes numerous empirically testable predictions.

It’s true that there’s no way to falsify the bare assertion that a cosmic designer exists. Nevertheless, the specific design arguments currently in play are empirically testable, even falsifiable,2 and involve testable predictions.

Consider the argument that Michael Behe makes in his book Darwin’s Black Box. There he proposes that design is detectable in many “molecular machines,” including the bacterial flagellum. Behe argues that this tiny flagellar motor needs all of its parts to function — is “irreducibly complex.” Such systems in our experience are a hallmark of designed systems, because they require the foresight that is the exclusive jurisdiction of intelligent agents. Darwin’s mechanism of natural selection and random variations, in contrast, requires a functional system at each transition along the way. Natural selection can select for present but not for future function.

Notice that Behe’s argument, contra the assertions of Judge Jones and the ACLU’s expert witnesses, rests not on ignorance or on a purely negative argument against Neo-Darwinism, but on what we know about designed systems, the causal powers of intelligent agents, and on our growing knowledge of the cellular world and its many mechanisms.

Behe predicts that scientists will not uncover a continuously functional Darwinian pathway from a simple precursor to the bacterial flagellum and, moreover, any detailed evolutionary pathway that is articulated will presuppose other irreducibly complex systems. How does one test and discredit Behe’s claims? Describe a realistic, continuously functional Darwinian pathway from simple ancestor to present motor. The flagellum might still be designed, but Behe’s means of detecting such design would have been falsified.

Darwinists like Kenneth Miller point to the hope of future discoveries, and to the type III secretory system as a machine possibly co-opted on the evolutionary path to the flagellum. The argument is riddled with problems, but it shows that Miller, at least, understands perfectly well that Behe’s argument is testable.

Miller tried to sidestep this obvious point in his expert testimony at the Dover trial by conceding that Behe’s argument was testable but insisting that it was a purely negative argument against Neo-Darwinism, not a positive case for intelligent design. This is mere wishful thinking on Miller’s part. Behe’s argument is also based on positive evidence for design. Behe points to strongly positive grounds for inferring design from the presence of irreducibly complex machines and circuits. This testable evidence is so powerful, so nearly ubiquitous, that it is often overlooked. Go out and find irreducibly complex machines, then find out, where possible, their causal history. Again and again one will find that the irreducibly complex machines (mousetraps, motors, etc.) were designed by intelligent agents. Indeed, every time we know the causal history of an irreducibly complex system, it always turns out to have been the product of an intelligent cause.
Miller has conceded that Behe’s irreducible complexity argument is testable. And we see that Miller’s assertion that scientists have tested and falsified Behe’s argument is itself false. Finally, Behe and other design theorists like Scott Minnich and Stephen Meyer have offered positive evidence for the design of the flagellum based on standard uniformitarian reasoning, reasoning well established in science.

To move from biology to astronomy and cosmology, in The Privileged Planet, Guillermo Gonzalez and Jay Richards describe how to falsify their design argument. They suggest that there is a correlation between the conditions needed for life and the conditions needed for diverse types of scientific discovery, and suggest that such a correlation, if true, points to intelligent design. They write:

The most decisive way to falsify our argument as a whole would be to find a distant and very different environment, which, while quite hostile to life, nevertheless offers a superior platform for making as many diverse scientific discoveries as does our local environment. The opposite of this would have the same effect — finding an extremely habitable and inhabited place that was a lousy platform for observation.

Less devastating but still relevant would be discoveries that contradict individual parts of our argument. Most such discoveries would also show that the conditions for habitability of complex life are much wider and more diverse than we claim. For instance, discovering intelligent life inside a gas giant with an opaque atmosphere, near an X-ray emitting star in the Galactic center, or on a planet without a dark night would do it serious damage. Or take a less extreme example. We suggested in Chapter 1 that conditions that produce perfect solar eclipses also contribute to the habitability of a planetary environment. Thus, if intelligent extraterrestrial beings exist, they probably enjoy good to perfect solar eclipses. However, if we find complex, intelligent, indigenous life on a planet without a largish natural satellite, this plank in our argument would collapse.

Our argument presupposes that all complex life, at least in this universe, will almost certainly be based on carbon. Find a non-carbon based life form, and one of our presuppositions collapses. It’s clear that a number of discoveries would either directly or indirectly contradict our argument.
Similarly, there are future discoveries that would count in favor of it. Virtually any discovery in astrobiology is likely to bear on our argument one way or the other. If we find still more strict conditions that are important for habitability, this will strengthen our case.

So contemporary arguments for intelligent design in both biology and the physical sciences are not only testable; they make predictions and are falsifiable in principle. Of course, if the arguments are true, then they are falsifiable only in principle, but not in fact (hardly a weakness in a scientific theory). We have given only two examples here. There are many other design arguments in biology, origin-of-life studies, and paleontology that are also empirically testable and that make predictions. Therefore, honest commentators should stop claiming that ID is empirically untestable, or that it makes no predictions. The claim itself has been tested and falsified. It’s time to move on to other and more pertinent aspects of the debate over intelligent design.


  • 1. Philosophers of science now know that “prediction” is too narrow a criterion to describe all scientific theorizing. Empirical testability is the more appropriate criterion.
  • 2. “Empirical testability,” “falsifiability,” and “confirmability” aren’t synonyms. “Empirical testability” is the genus, of which falsification and confirmation are species. Something is empirically testable when it is either falsifiable, confirmable, or both. Moreover, something can be confirmable but not falsifiable, as with the Search for Extra-Terrestrial Intelligence (SETI) or the existence of a cosmic designer. Both of these claims are still empirically testable. Further, recent work in the philosophy of science has revealed the degree to which high level scientific theories tend to resist simple refutation. As a result, Karl Popper’s criterion of “falsifiability,” which most commentators seem to presuppose, was rejected by most philosophers of science decades ago as a litmus test for science. Nevertheless, it’s certainly a virtue of scientific proposals to be able to say what evidence would count against it.

Jonathan Witt

Executive Editor, Discovery Institute Press and Senior Fellow, Center for Science and Culture
Jonathan Witt, PhD, is Executive Editor of Discovery Institute Press and a senior fellow and senior project manager with Discovery Institute’s Center for Science and Culture. His latest book is Heretic: One Scientist’s Journey from Darwin to Design (DI Press, 2018) written with Finnish bioengineer Matti Leisola. Witt has also authored co-authored Intelligent Design Uncensored, A Meaningful World: How the Arts and Sciences Reveal the Genius of Nature, and The Hobbit Party: The Vision of Freedom That Tolkien Got, and the West Forgot. Witt is the lead writer and associate producer for Poverty, Inc., winner of the $100,000 Templeton Freedom Award and recipient of over 50 international film festival honors.