Dispatches from the Creation Wars

Behe and Falsification

Over at UD, GilDodgen has a long quote from Michael Behe claiming that ID is easily falsified while evolution cannot be. The quote is from the DVD Case for a Creator (this should of course really be “Case for an unnamed, undefined and possibly non-divine intelligent designer”, but apparently they were feeling a bit lazy that day). I want to look at both parts of Behe’s claim. Here’s the first:

The National Academy of Sciences has objected that intelligent design is not falsifiable, and I think that’s just the opposite of the truth. Intelligent design is very open to falsification. I claim, for example, that the bacterial flagellum could not be produced by natural selection; it needed to be deliberately intelligently designed. Well, all a scientist has to do to prove me wrong is to take a bacterium without a flagellum, or knock out the genes for the flagellum in a bacterium, go into his lab and grow that bug for a long time and see if it produces anything resembling a flagellum. If that happened, intelligent design, as I understand it, would be knocked out of the water. I certainly don’t expect it to happen, but it’s easily falsified by a series of such experiments.

This is the same argument that he and Scott Minnich made in their testimony in the Dover trial; it didn’t work then and it won’t work now, for two primary reasons: first, because such an experiment could never approximate the actual conditions in which the flagellum evolved, and second, because even if a flagellum did evolve, the ID advocates would not actually accept it as a falsification of irreducible complexity. Let’s take the first argument first.

Frankly, Behe is being disingenuous here when he claims that scientists could just remove the flagellum from a bacterium and see if one evolves again. He knows this because he and his colleagues love to do these amazing probability calculations for how unlikely it would be for the flagellum to evolve step by step, and some of the variables included in those calculations are variables that simply cannot be replicated in a lab. Bacteria have been evolving for around 3.8 billion years on the Earth, and they exist on earth in numbers that can barely be expressed even mathematically.

There simply is no way to replicate the number of sequential trials (i.e. the total population of bacteria or the amount of genetic variation within that population) or the amount of time involved. A researcher might work with a population of a few billion bacteria for his entire professional career of 50 years or so and he would not have replicated the actual population or time involved in nature to even one billionth of the actual numbers. And that’s not even counting the fact that we can’t possibly replicate all of the relevant selective pressures that various subpopulations might have been under that allowed the mutations that developed the flagellum to become fixed in the first place.

Behe knows all of this, and we know he knows all of this, because when he’s done his own research even on a much less complex biochemical system, a single protein binding site, he had to use a computer simulation to do it. When he and Snoke did the work for their 2004 Protein Science paper, they knew that even for a relatively simple experiment involving only a few point mutations in a single enzyme within a bacteria, they could not possibly replicate real world conditions in the lab.

They knew that the only way they could even come close was by using computerized artificial life programs to speed up the whole process. And even then, they rigged the conditions to make it as unlikely as possible and as unlike the real world as possible, but the computer simulation still showed that a binding site that Behe himself characterized as irreducibly complex could evolve in 20,000 years. Yet here he is demanding that scientists do an actual experiment with actual bacteria, the numbers of which could not possibly be contained in a lab, on the evolution of a much more complex biochemical system that would almost certainly take longer to evolve than the whole of recorded human history.

Reasonable? Of course not. This is like arguing that a solar system could not have come together on its own without divine intervention, and that you can easily falsify that claim merely by creating a solar system in your laboratory – assuming, of course, that you had a laboratory that could hold and contain a 50 million mile thick fusion nuclear reactor at temperatures that would melt the earth. This is precisely what Judge Jones was referring to in the Dover ruling when he said that the IDers intentionally demand an absurd level of proof that they know cannot be met.

But here’s the punchline: even if a scientist did manage to do such an experiment and a flagellum did re-evolve in the lab, would they really accept this as proof that ID was false? Not on your life. They would immediately make two arguments:

1. “All this shows is that it can only happen in the lab, where the scientist intervenes as an intelligent designer to ensure the result. This only proves that intelligent intervention is required to bring about a flagellum”; and,

2. “If the information for the evolution of the flagellum was front loaded into the bacterial DNA by the Intelligent Designer, then of course a flagellum would re-evolve if you removed it; it was designed that way.”

How do we know that they would make those arguments? Because they’ve already made them. Here is Behe himself on front-loading:

Suppose that nearly four billion years ago the designer made the first cell, already containing all of the irreducibly complex biochemical systems discussed here and many others. (One can postulate that the designs for systems that were to be used later, such as blood clotting, were present but not “turned on.” Om [resent-day organisms plenty of genes are turned off for a while, sometimes for generations, to be turned on at a later time.)

Mind you, as a biochemist Behe knows perfectly well what happens to unexpressed DNA; because it’s not expressed in the phenotype it can’t be selected for, so mutations accumulate massively over the generations until the genes are completely useless. Thus, along with this front loading he also has to posit that the undefined designer (wink, wink) also intervened constantly to prevent that from happening. Given that level of constant intervention in the natural order, how could any experiment like this possibly falsify such a designer’s actions? It simply can’t happen, not even hypothetically.

Now let’s turn that around and ask, How do we falsify the contention that natural selection produced the bacterial flagellum? If that same scientist went into the lab and knocked out the bacterial flagellum genes, grew the bacterium for a long time, and nothing much happened, well, he’d say maybe we didn’t start with the right bacterium, maybe we didn’t wait long enough, maybe we need a bigger population, and it would be very much more difficult to falsify the Darwinian hypothesis.

But this is a profoundly silly argument, based upon the same ridiculous premise as his argument above. If it isn’t possible to replicate the population size, the amount and type of genetic variation, the amount of time involved, or the selection pressures specific to the environment at the time – and it’s not – then of course you can’t falsify evolution in this manner. But that does not, of course, mean that evolution can’t be falsified or tested at all, nor does it mean that we can’t use lab research to confirm smaller parts of that testing.

Because the evolution of these biochemical systems happened primarily in the distant past and took place over such long periods of time, we will never have a videotape-level display of how exactly they took place, which is the only thing that will satisfy the IDers (as Behe made very clear in his testimony in Kitzmiller). But we can use this kind of research to help us understand how they developed in a number of different ways. And Behe accepts all of those ways, and accepts that they can in fact demonstrate plausible evolutionary pathways for the development of complex biochemical systems.

He’s perfectly fine, for example, with the evolution of the antifreeze proteins in arctic fish having developed via mutation and selection, despite the fact that we don’t have the kind of undeniable mutation-by-mutation videotape of how it happened. But what we do have is precisely the kind of lab research that Behe rejects when it comes to the flagellum, research that compares specific genes in closely related species to see, for example, how a gene in one species is duplicated in another species, which provides the raw material necessary for adaptation. We have the research showing that the antifreeze proteins are virtually identical to the pancreatic protein trypsinogen, and much more. We can infer from this the likely pathway taken to evolve a particular trait. His arguments in regard to the flagellum are a textbook example of special pleading.


  1. #1 Dave S.
    December 28, 2006

    1. “All this shows is that it can only happen in the lab, where the scientist intervenes as an intelligent designer to ensure the result. This only proves that intelligent intervention is required to bring about a flagellum”; and,

    And HERE is an example of Dembski accusing Tom Schneider of exactly that…of “smuggling” CSI (i.e. design) into his program.

  2. #2 Art
    December 28, 2006

    A nice post, Ed. If I may add a few comments:

    If we take Behe’s “experiment” seriously, then one may ask what conclusions one would draw, given either of the two intended outcomes. Without elaborating, we need to be reminded that the conclusions will be contingent on the results of control experiments. Basically, a negative result means little if one has not built into the study positive controls that show that the study has been properly set-up and executed. A positive result means little if one has not performed negative controls that rule out the annoyances (contamination, if we are doing PCR, is one example) that dog the bench scientist. Behe’s “experiment” as proposed has no positive or negative controls, nor can it. This makes the “experiment” little more than an exercise in rhetoric, and certainly nothing that deserves to be taken as a serious scientific statement.

    Switching gears, putting things into a more familiar perspective (at least I hope its familiar to many readers here – if not, get out there and participate!): I can imagine Behe’s “study” at a science fair, and I can see the three issues that are stumpers. First and foremost, students (and their parents) are taught that a science project involves a question whose scope is appropriate for investigative techniques. Behe’s project fails on this regard. Second, there are the matters of independent and dependent variables. I suspect that Behe could not tell us what these variables are in his project. (Worse – if he tried, he would see quickly how poor the project is.) Third are the controls. The preceding reveals this flaw. The bottom line – Behe’s attempt doesn’t even meet the standards we try to teach 3rd graders.

  3. #3 GH
    December 28, 2006

    Black is White, red is yellow. The fact that men who are(or used to be) intelligent, like Behe, spend so much of their lives like this is simply tragic.

    Every once in awhile you just want to shake him and say wake up or what is wrong with you. It’s as if he has an idea and has to defend it no matter the cost regardless of publicly and professionally being rebuked. That seems to be more ego than anything.

  4. #4 tacitus
    December 28, 2006

    The Case for a Creator DVD is from Lee Strobel who wrote the book of the same name. Nothing to do with science–it’s pure apologetics.

  5. #5 Troublesome Frog
    December 28, 2006

    I think that they would make a third argument as well. The flagellum may not be irreducibly complex, but X certainly is. Keep substituting values for X until there are no more gaps for God (err… the Designer) to fit in. That should keep things going for generations.

  6. #6 Ed Brayton
    December 28, 2006


    Thanks for that link, which brings up another tangential issue to this: how IDers handle artificial life research. Behe himself, during the Dover trial, criticized Rob Pennock and the Digital Evolution Lab for their paper in Nature using AVIDA to show how irreducibly complex features could be produced; his criticism, ironically, was that the parameters they used were not like those of the natural world. That made it all the more funny when he had to admit, under questioning, that the parameters they had used ignored several sources of variation found in the real world, used population estimates that were far too low and ignored the possibility of any function at all for intermediate steps – all things incongruent with real world conditions – and still came to the conclusion that this allegedly irreducibly complex multi residue binding site could evolve on its own in a mere 20,000 years (and if you use more realistic population figures, chop a couple orders of magnitude off that time frame). And here we have Dembski criticizing the use of such digital evolution platforms for research completely because they “build in CSI” from the programmer, yet he praises Behe’s use of that same kind of research as the “nail in the coffin” of evolution. As the old saying goes, pick a horse and ride him guys. You never know which side of their mouths these guys are talking out of.

  7. #7 Scarlet Seraph
    December 28, 2006

    I think the Frog has made a good point: the argument of ID is not that the flagellum is the product of design; the argument is that one or more things in the universe is the product of design. Or, more precisely, falsification would require demonstration that no designed objects exist – a universal negative and consequently not capable of demonstration.

    I am leaving out the trivial point that intelligent design occurs all the time – by humans, other apes, ants, crows, etc. The ID movement is only concerned with unknown designers conveniently operating in moments of spacetime we can’t look at directly.

  8. #8 jackdan
    December 28, 2006

    I don’t believe even Behe would accept the results of such an experiment as disproof of ID. As we have seen many times, including at Dover, he simply moves the goalposts back.

    “Oh, the pufferfish doesn’t have all the clotting elements? I meant that the SUBSET of elements in the pufferfish was the ‘irreducibly complex’ component.”

    This is a variant on the counterargument offered by Troublesome Frog, above.

    Another possibility:

    “Just because the flagellum COULD have evolved, doesn’t mean it DID evolve. You haven’t disproved anything.”

  9. #9 Jason
    December 28, 2006

    Also, as I think was mentioned in the court, the knock-out test for a bacterial flagellum is a test of evolution, not a test of ID creationism.

    If such a test were conducted and no flagellum evolved, all it would show is that that specific strain of that specific species did not evolve a flagellum under those specific circumstances.

    It would certainly not equate to: “The first flagellum to ever appear in any bacterial species was intelligently designed”. To suggest that it would is about a specious logic as can be exhibited.

  10. #10 quitter
    December 28, 2006

    You’re dead on. This is the classic “impossible expectations” tactic of denialists. The only experiment that will convince them is beyond the scope of human technology, and probably will remain so for a good long time. Typical.

  11. #11 Coin
    December 28, 2006

    And it probably would be redundant here to point out that his “falsification” test, even if it were a falsification test, doesn’t even have anything to do with intelligent design– just “irreducible complexity”, which is an argument against evolution, not an argument for ID.

    But, I wanted to point it out anyway.

  12. #12 Tony Whitson
    December 28, 2006

    First, just to mention a typo that needs to be corrected:

    Om [resent-day organisms

    should be change to In present-day organisms.

    In the paragraph after that block quote from Behe, Ed writes:

    Mind you, as a biochemist Behe knows perfectly well what happens to unexpressed DNA; because it’s not expressed in the phenotype it can’t be selected for, so mutations accumulate massively over the generations until the genes are completely useless. Thus, along with this front loading he also has to posit that the undefined designer (wink, wink) also intervened constantly to prevent that from happening. Given that level of constant intervention in the natural order, how could any experiment like this possibly falsify such a designer’s actions? It simply can’t happen, not even hypothetically.

    Yes, but it seems to me there’s a more generally compelling consequence that would follow even without such a great level of Disine intervention being required. In her talk in the KU series this fall, Genie Scott made the basic point that no experiment could ever rule out supernatural intervention, because no experiment could ever control for that. How could you ever rule out the explanation that the Disigner may have simply zapped a new flagellum on the spot, maybe to test a scientist’s faith? For that matter, how could you rule out the possibility that Tiktaalik was created on the spot (along with the material conditions that would mislead researchers as to its antiquity) just the day before it was discovered?

    So even if a modest intervention were all that was required, it is in principle not something that can be ruled out by any kind of test available to natural science, as such. So whatever someone will believe about the matter, the ID hypothesis is not within the purview of natural science.

  13. #13 Unsympathetic reader
    December 28, 2006

    If Behe was interested in scientific evaluations of possible routes of evolution to IC systems, he’d examine the most recently emerged IC systems he could find in species that have a good record or many sibling species. In other words, systems that have a reasonable chance of practical evaluation. But note how Behe keeps looking backwards… Did the mammalian blood clotting system have too many possible precursors for his taste?

  14. #14 Ginger Yellow
    December 29, 2006

    This is why I find it impossible to believe that the ID advocates (as opposed to their followers) are acting in good (if misguided) faith. As a trained scientist, Behe knows full well that this isn’t falsification of ID, for all the reasons given above (especially the “well maybe the flagellum isn’t designed, but…” argument), and also because irreducible complexity isn’t a necessary corollary of the central ID hypothesis. It’s just an anti-evolutionary argument attached to an assertion of design. Even if the flying spaghetti monster were to determine that every single irreducibly complex system in the universe had evolved (or formed through other natural processes), it wouldn’t rule out some other “proof” of design.

    I’m not a fan of anti-tenure campaigns, for obvious reasons, but this sort of malicious anti-science is grossly irresponsible and clearly falls under professional misconduct.

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