Intelligent Design: The Final Word, Part 3

The central question I have been trying to satisfy myself about with these notes is the following: is there a way to formulate Intelligent Design as a scientific theory? (See part 1 and part 2.)

By definition, a scientific theory is a model of a part of the world that makes verifiable and falsifiable predictions about specific observations. To answer this question, I will reformulate the statement of ID. Behe’s formulation looks like this (this is not a quote, I’m summing up his argument):

My summary of Behe’s argument:

Although evolution certainly takes place at a macroscopic level, certain biochemical processes inside our cells cannot be explained by step-by-step evolutionary processes because they involve several interacting parts that are each required for the process to function: they are _irreducibly complex_ and so these must have been designed by an intelligent agent. It is mathematically possible for a random process like evolution to produce one of these systems, but the probability is absurdly low because all parts must mutate to their working form at the same time. The probability that all of our irreducibly complex systems evolved in this way is even more negligibly small.

I want to say up front that I am not going to attack the probability part of this argument in order to argue whether it is scientific. It is perfectly reasonable to say that something we observe has a very low probability of arising from some process, and to remove evidence from the applicability of that process in so doing. If you can demonstrate what that probability is. In a further essay I will look at this issue more closely, but only when I want to discuss the correctness of ID, not whether it is a scientific theory in the first place, which is our current aim.

I’m going to reformulate the statement above summarizing Behe a couple times to draw out out what I’m looking for. I expect that an ID enthusiast will object to my reformulations at some point because the conclusion will follow immediately from the final reformulation, but I wonder where the objections will arise exactly.

Reformulation 1:

Certain subcellular processes are irreducibly complex. Irreducible complexity implies design by an intelligent agent, because to arise randomly by a mutation has nearly zero probability. Therefore subcellular processes were designed by an intelligent agent.

I will now add to the discussion that I fully grant that all of Behe’s examples are in fact irreducibly complex, which simply means that the systems involve several interacting parts without any one of which the system fails to function. It’s a simple to define concept, and surely his examples are all in fact irreducibly complex. Granted. Now, also losing the bit about probability, we can reformulate:

Reformulation 2:

Evolution cannot explain irreducible complexity.

This is entirely equivalent to Behe’s statement of ID, once you remove the question about whether the systems are irreducibly complex, and replacing the caveat about probability with the blank statement “cannot explain.” If you agree with the complexity part, then all ID says is that evolution cannot explain this complexity.

The problem with ID is that this not the statement of a scientific theory. It is the contradiction of one, namely of evolution. It only makes one prediction, that evolution will not be able to explain irreducible complexity. The only way to study this idea is to study the evolution of molecular systems and try to explain how the irreducible complexity of some particular system came to be. See, ID doesn’t substitute anything for evolution, it merely fills the gap it creates with the Designer. It cannot make any new predictions, and it doesn’t try.

Here is an analogous scenario. The 6 o’clock news reports that there are crop circles on a farm outside town. A scientist on TV expresses his theory that it is the work of teenagers playing a prank. Another scientist puts forward the theory that the crop circles cannot be explained as the work of humans, they must be the work of extraterrestrials. Furthermore, the second scientist argues that his theory is just as scientific as the first theory, because they both purport to explain a particular phenomenon. The problem with the second theory is that its central claim is that the first claim is wrong, and in so doing it creates a gap, which it then fills with extraterrestrials. But the gap is not a theory, just the contradiction of one. The way to proceed to investigate crop circles, then, is to pursue the first theory and try to find a natural explanation. That’s the same course of action we’d take if there was no second theory. And of course crop circles were eventually found to be easily made by teenagers using planks of wood with rope handles to press down the crops in just a few hours overnight.

It’s the same with ID. The way to pursue this issue is to investigate natural ways that these irreducibly complex systems may have come about. That’s the same approach we’d take if there was no ID theory. ID theory adds nothing and makes no claims other than to contradict an existing line of inquiry.

The funny thing is that ID is falsifiable. Finding a viable evolutionary path for the cilium or any of the systems Behe is interested in will falsify ID, and Behe himself points this out. That’s an important point, because when I started this line of thinking I assumed I’d be determining that ID isn’t falsifiable. What I’ve learned instead is that ID isn’t predictive. No theory whose statement can be summarized as “that other theory over there won’t work in this case” is predictive. It doesn’t make any claims of its own that can be tested, and so the only way to investigate it is to investigate the original theory, making the contradictory theory actually meaningless.

What does this tell us about teaching ID in science classes? My short answer is that since it is not a scientific theory, it should not be taught. It certainly should not be required, and probably its absence should be required. But why? Because science is about skepticism, model-building and model-testing. It’s never about authority, never about personal preferences. It makes no contact with our political or spiritual structures. It is completely confined, completely focused on material predictions that can be tested and falsified. Theories that limit the domain of science, the way ID claims science will never apply to certain biological systems, may or may not be correct. But science does not place such limitiations on itself, for to do so is impossible within the framework of science. Scientists will be the first to admit that they have a poor understanding of how evolution applies to sub-cellular systems. Science demands such concessions – science is the requirement to make such concessions. And that state of affairs may continue to hold for a million years for all I know. It does not change the central point, that science is a process for adding to the accuracy of our models, not for defining boundaries.

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Greg Langmead
Machine Learning Engineer

I am a software engineer and mathematician. I work on NLP algorithms for Apple News, and research homotopy type theory in CMU’s philosophy department.