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Intelligent Design Is Testable. Is Darwinism?

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A familiar canard is that intelligent design isn’t science because it makes no empirically testable claims or predictions. The objection is a canard because intelligent design makes many empirically testable claims and predictions.

Consider Darwin’s Black Box, published twenty years ago as we recall in the new documentary Revolutionary. In the book, molecular biologist Michael Behe points out that the neo-Darwinian mechanism lacks foresight. It requires a functional system at each mutational step on the evolutionary path, and it doesn’t give a fig for some distant goal. If the thing can’t compete, survive, and reproduce, it gets weeded out of the evolutionary game of life — plain and simple.

Behe went on to argue that the bacterial flagellum needs all of its parts to work and there’s no pathway for it to have evolved one small neo-Darwinian step at a time, even allowing for the possibility of nature co-opting simpler machines serving other functions.

Behe calls this feature “irreducible complexity,” and says it’s a hallmark of intelligently designed systems. Whether it’s a mousetrap, a bicycle, an integrated circuit, or any of countless other machines, any time we find an irreducibly complex device and can trace it back to its source, the source always turns out to be an intelligent agent.

Reason also tells us why this is so. The work of fashioning irreducibly complex devices requires foresight and planning, a capacity uniquely the domain of mind or intelligence.

Behe predicted that scientists would not uncover a continuously functional Darwinian pathway from a simple precursor to the bacterial flagellum, and that any evolutionary pathway that someone might describe would presuppose other irreducibly complex systems. He further argued that for all of the above reasons taken together, intelligent design is the best explanation for the origin of the bacterial flagellum.

How might one test and discredit Behe’s argument? Demonstrate, or at least describe, a realistic, continuously functional Darwinian pathway from simple ancestor to present motor. This would falsify Behe’s design argument.

Darwinists like Kenneth Miller look to future discoveries, and to the type III needle complex as a machine possibly co-opted on the evolutionary path to the bacterial flagellum. The argument is riddled with problems, while Behe’s case is more secure than ever twenty years on. Miller’s attempt, however, shows that he at least understands perfectly well that Behe’s argument is testable.

In his expert testimony at the Dover court trial, Miller tried to sidestep this obvious implication by conceding that Behe’s argument was testable but insisting it wasn’t science because it was a purely negative argument against neo-Darwinism, not a positive case for intelligent design.

But no, Behe’s argument is also based on positive evidence for design. It rests on what we know about irreducibly complex systems, on what we know about the causal powers of intelligent agents, and on our growing knowledge of the cellular world and its many mechanisms.

Testing a Cosmic Design Hypothesis

Consider another design argument, this one in astronomy and cosmology. In The Privileged Planet, Gonzalez and Richards show that there is a striking correlation between the conditions needed for life and the conditions needed for making many types of scientific discovery. They argue that such a correlation, if true, points to intelligent design. They then point out how to falsify their design argument:

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.

The Inertia Objection to Intelligent Design

There’s another objection purporting to show that ID isn’t really testable. The objection goes like this: Does anyone really believe that if, say, Michael Behe’s bacterial flagellum argument for design was decisively falsified, all the ID folks would pack it in? Of course not!

That objection fails for a couple of reasons. First, it’s the nature of high-level scientific theories that they lead to a host of predictions, and the theories can be tweaked as new evidence arrives. The overall theory doesn’t collapse at the first evidential threat.

If that rendered a high-level theory untestable and unscientific, then modern evolutionary theory itself would be unscientific, since many of the things its leading defenders predicted based on the theory have turned out to be false, with various patches and adjustments offered along the way to keep it afloat.

Second and related to the previous point about high-level scientific theories, if Behe’s flagellum argument did fail, then design theorists would still stick to ID for the very good reason that there would remain other powerful lines of evidence for intelligent design — from the origin of the first life to the fine tuning of the laws and constants of physics, to the correlation between life and discovery described in The Privileged Planet.

Follow the Evidence

I’ve offered only a couple of examples of testable design arguments here, but there are many others. Of course, if the arguments are true, then they’re falsifiable only in principle, but not in fact — hardly a weakness in a scientific theory!

So, rather than beating the dead horse of un-testability, design doubters would do well to focus on a more fruitful question: Where does the evidence lead? What is the best, most causally adequate explanation for things like the bacterial flagellum, biological information, the fine-tuning of the laws and constants of physics, and the strong correlation between life and discovery?