Creation Myths: A chat with Michael Behe on Irreducible Complexity

If and when “purposefully arranged parts” comes up, Behe should be pressed. For example, what would be his comments on the fact that a tornadic thunderstorm is an irreducibly complex assemblage of purposefully-arranged parts:


(Taken from Tornado - an overview | ScienceDirect Topics)

Heck, one can estimate the “information” of such a system forming by chance, by counting the numbers of (water) molecules and limiting by just one the many degrees of freedom available to each for each of these molecules. From a long-ago forum:

Recall that the informational content of genomes is usually estimated by “calculating” that fraction of all possible sequences (nominally, amino acid sequences) that can satisfy a particular specification. We can use a similar strategy to guesstimate the “information” carried by water vapor molecules in a storm. The hard part is deciding how few of all of the possible states that are available to a particular water molecule are actually “used” in a storm. Now, one can count up all possible positions in the storm, interactions with all possible partners, etc., etc., and realize that the number is probably rather small. But, for the sake of argument, let’s pick an arbitrarily large number – let’s propose that only 1 in 10^30 states of any given water molecule is excluded in a storm.

Starting there, we need only count the number of water vapor molecules in a storm and estimate the “probability” that the arrangement found in a storm would occur. If we arbitrarily think in simple terms - a storm that is 5x5x7 miles in size, a temperature of 30 degrees C, a partial pressure for water vapor of about 32 mm Hg, an overall atmospheric pressure of 1 atm - then the number becomes (roughly) 1x10^-30 raised to the number of water vapor molecules in the storm (which is about10^36). Which in turn is about 10^-10^6 (that’s 1 divided by 1 million!).


What stood out to me almost right away is within the first five minutes, Behe said (paraphrased):

  1. If it can be shown an IC system of a certain complexity can evolve, then systems of equal or lesser complexity are not impossible for evolutionary processes to develop.
  2. You have to sufficiently document; you can’t just say that one IC system is similar to another demonstrated evolved system and infer it evolved as well.

To me (and feel free to jump in if I misunderstood something—I don’t think I did), these two statements are seriously in tension.

And toward the latter half of the chat, Behe admitted that there were IC systems that evolved, but it wasn’t very impressive because of high mutation rates. Sort of a pivot to probabilities. At this point, I don’t even know why the fact of a system being IC is even relevant at all if we’re just talking mutation rates and probabilities. If somebody can set me straight on that, please do.


This was my impression as well, and by the time we got there, Behe was contradicting what he said at the very beginning, when we very specifically characterized his hypothesis - that the presence of IC precludes evolution. And I was very “well, are you SURE sure that’s what you mean?” and initially the answer was yes but then by the end it was “well, it depends”.


So… if we know how something evolved, Behe will accept that it (and anything equally complex) could have evolved, but he won’t say that anything more complex than that could have evolved.

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You’re very straight on that. For fun, try convincing some of Behe’s devotees here on that point.

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But was either unable or unwilling to explain how to quantify the relevant distinctions.

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The most problematic of all Behe’s claims is that he essentially seems to reject historical inference in analyzing this question of IC. He is saying effectively that we can’t infer the origin of an IC system of some unspecified level of complexity by comparative analysis to convince Behe. Only if we show it evolve in real time in the laboratory will he apparently concede that it is possible.

Behe is simply a more rhetorically practiced version of Ken Ham doing his “were you there?” routine, but couched in the technical jargon of molecular biology.

Isn’t it obvious that increasingly complex IC systems are merely a matter of more time?

If it is a matter of decades to get a two or three-component IC system, why can’t a 30-component system evolve in a million years?

Behe seems to be saying that the rate at which additional components are added to the system must drop exponentially off with time (this is the entailment of his claim that the probability drops off exponentially with each added component), so by the time we get to a 10-component system we must wait superastronomical time periods to add another. That is the implications of his statements. But why must it do that?


The quote you showed in the beginning was that Behe claimed that irreducibly complex systems offered a powerful challenge to the Darwinian mechanism. This is his claim.

Your attempt to force a hard falsifiability based on rigid definitions is not his argument.

And then we went into considerable detail to determine the extent to which IC supposedly precludes the evolution of such systems - and the claim was that it does preclude the evolution of such systems by any undirected mechanism. That was the claim, and I was extremely cautious in terms of over-interpreting it. Go back and watch that part - I’m trying very hard to make sure I wasn’t getting out over my skis.


But we do hypotheses in real science. Behe’s hypothesis, never stated as such for obvious reasons, is that IC systems cannot evolve.

Then his claim is a contradiction. If his argument is that he has a challenge to science, his claim must be definable. If his claim isn’t definable, he doesn’t have a challenge to anything.


Except in this case he did state it like that quite explicitly.


To be fair, I believe he does clarify quite a few times that some very simple IC systems can evolve, but then that’s the point of contention how complex is too complex to be accessible? Behe seems unable to give a really objective criteria of the dividing line, which is obviously a problem.


In which case–your video?

AFAIK, the only statement that comes close to being explicit was the one extracted under oath in the Dover case.

We may see it as a hypothesis, but Behe’s followers definitely don’t. Behe is very talented in hoodwinking them (and maybe himself) in that way.

Never up front with laypeople, though. And then it becomes just another argument between experts, which helps Behe sell books while never testing his hypothesis. That’s the real “ID” here. Idea: what if we framed it more accurately by calling it “intelligent avoidance of doing science” (IADS)?

I wouldn’t say that he “seems unable.” I would say that he strenuously avoids giving criteria because on some level, he knows that his hypothesis is globally false. It’s also not obvious at all to his acolytes.

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This is where he does two things.

First is his “Edge” of evolution-type arguments, where he will reference his “waiting longer for two mutations” paper and speak about chloroquine resistance.

Second is he invokes the assumption of an exponential decline in the probability of adding more and more components to a system.

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No. Not to me at least.

I’m open to correction here, but I have a hard time seeing this as a “two or three-component IC system.” This is my understanding:

We have an organism that already has a pre-existing anaerobic citrate metabolism trait. Through a gene duplication, and a couple of mutations related to acetate metabolism (what I gathered from this video, and this point) , it can now metabolize citrate aerobically. It seems like a stretch to me to call this a “two the three component IC system”

I also read from this comment from @dsterncardinale (I might not have linked that properly):

My favorite thing about this experiment, other than the simple fact that it exists, is that the aerobic citrate metabolism trait is a directly observed experimental refutation of irreducible complexity [emphasis mine]

And so as I’m reading this, this ‘refutation’ can be extrapolated to any IC challenge such as blood clotting cascade, or ATP synthase.

Again, that seems like a stretch, an over-extrapolation. It makes me question the phrase I hear repeated: “IC has been refuted”. Just being honest…

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Climbing Mt. Everest is a powerful challenge for human beings, and yet they do it all of the time.

It depends on how you frame the IC hypothesis. If it is framed, as Behe did during out conversation, as “any IC system cannot evolve via undirected processes”, then it has been refuted. Now he then went on to attach a bunch of other conditions to that over the next 45 minutes, such as the claim that the non-duplication parts of the cit+ trait were not part of the same “system” so it doesn’t count, a qualification which, honestly, does not seem reasonable.


Why not?

Even Behe concedes that a 2-3 component system can evolve in a matter of decades. If he’s right about this, then why does it not follow that more components just take more time? Is there some sort of magical barrier that comes down and says “nope, that’s enough here, no more!”?

There’s a function: Citrate transport under aerobic conditions.

To implement this function you need at least two components:

  1. A promoter that ensures the the citrate transporter gene is actively transcribed when oxygen is present.
  2. The gene encoding the citrate transporter.

If you remove the promoter, the function stops working. If you remove the gene encoding the transporter, the function stops working. So both components are required for the function aerobic citrate transport.

Irreducible complexity: If you remove a component from a system that contributes to it’s function and it stops working then it is irreducibly complex.

The function evolved. Thus an irreducibly complex function requiring at least 2 components evolved.


I don’t really see what the problem is here. What is being argued is that the “irreducibility” of some extant system does not constitute a barrier to it’s evolution.

The argument is that if we can show that systems composed of multiple interacting parts that contribute to it’s overall function, which will stop functioning if certain parts are removed(so they are irreducible), can still evolve, then we have shown that at least this aspect of the argument from irreducible complexity is not a challenge to evolution.

So it does not suffice to merely point out that ATP synthase(for example) has a function which, if you remove parts of it, it stops being able to perform. Because it has already been shown that this kind of mutual dependence relationship between individual components can evolve, by cooption(exaptation) of components that themselves performed other functions (and which they still some times do), or used to be part of other systems.

This is why Behe went on to move the goalposts and insist that there must be some sort of degree of complexity(number of parts of the system becomes the new crucial aspect) beyond which irreducibly complex systems cannot evolve.

Behe originally argued his point about the irreducibility being unevolvable by focusing his argument on a Darwinian emergence of the system, whereby he argued against a gradual increase in the basic function as the system elaborated. He said the system’s irreducibility prevented this type of gradual “Darwinian”(cumulative selection-dominated) emergence where the function came early with a few components, and then gradually improved (with each step being selected for cumulatively because the system functioned better and better) as more and more components eere added. His point of course being that if you remove a component and the system stops working, then there is no such step-wise Darwinian pathway to the extant complex system’s function.

Biologists have responded in two ways. First by pointing out there are neutral pathways to complexity, and by pointing out that parts can be coopted from other functions, and the system as a whole can be exapted to change function along the way.

Behe has responded to the point about neutral evolution by saying neutral evolution just makes it very unlikely because you’re missing selection to aid the fixation of each new step. And Behe has responded to the point about exaptation by arguing that (paraphrasing) the probability drops off with each added component. (A point which I have above tried to argue seems without basis).

Biologists have responded to Behe’s claims about neutral processes in evolution by saying Behe ignores constructive neutral evolution, which can be inherently biased towards complexity. I have not seen him respond to this.