Pharyngula

Irreducible complexity, again?

We’ve had a creationist named “biasevolution” babbling away in the comments. He’s not very bright and he’s longwinded, always a disastrous combination, and he tends to echo tedious creationist tropes that have been demolished many times before. But hey, I’m indefatigable, I can hammer at these things all day long.

He brings up irreducible complexity (IC), Behe’s ever-popular contribution to the creationism debate. Behe’s version of the idea was published in 1996, so we’ve had almost 20 years to refute it — successfully! — so it gets a little old seeing it brought up again and again.

If you really, really understood IC you WOULD NOT argue with it. You would find that it would be as silly as say arguing against variation or heredity, or the principle of flotation. The reason is this: if you must design a system towards some given function or set of function you would need critical parts. For one, you must have a source of energy for that system. Two, it must have a set of interacting parts that work towards the function you want, you can even add parts to fine-tune it to better perform that function (eg adding capacitors to fans to smoothen out voltage reduced). To then argue that an eye ain’t IC is laughable. All the accounts supposedly falsifying IC or showing how it evolved routinely assume simple IC precursors or point to other IC systems lacking a part and say IC is refuted for a system as Miller did in the blood clotting cascade (akin to arguing because some cars don’t use clutches cars ain’t IC).

I do understand IC quite well. I’ve read Behe’s books. I’ve had it thrown in my face many times, often by creationists who don’t understand it (Jerry Bergman’s claim that carbon all by itself is irreducibly complex was particularly memorable). Biasevolution’s version isn’t quite that bad, but it’s still awful.

And it’s wrong.

First, there’s the problem of begging the question: if you must design a system towards some given function. You’re trying to argue that something is designed, and the first thing you do is demand that we accept the premise that it is designed?

The whole point of the IC concept is that if you examine a final ‘design’, and there’s no way to remove a piece of the structure without destroying its function, then it could not have evolved in a stepwise fashion, as evolution would predict. That’s really all it says: that evolution is falsified if you identify a pathway, for instance, that would not be functional if you removed a piece. It’s naively appealing — but only if you think evolutionary change must be symmetrical and reversible. But we actually evolve irreducibly complex systems all the time.

Let’s work through a simple example. Here’s a pathway, or circuit: a battery, a switch, and a light bulb (I’ve left out the one wire to complete the circuit, just to simplify it all; don’t take it too literally.) You close the switch, the bulb lights up. Simple.

circuit1

Here’s a simple expansion of that circuit. I’ve merely duplicated the switch, so now there’s two of them: close either one, the bulb lights up. This might not be a trivial change to an electrician, but it is to a geneticist — genes get duplicated all the time, and typically all it would do is add a redundant element. So this is a routine variation of a kind that is frequently observed in biological systems.

circuit2

Now we change one wire, shifting the output of the first switch from directly activating the effector (the bulb) to feeding into the second switch. Now to light up the bulb, you must close the second switch, but the first switch is redundant.

circuit3

The biological analog to this would be if, for instance, a protein in a biochemical pathway lost its ability to bind a terminal substrate, but could still activate an intermediate protein. Again, this happens.

Now you could imagine a mutation that destroyed the first switch, and the whole system would simply revert to the initial condition, in which a single switch controls the bulb. That happens, too — we find dead genes (called pseudogenes) all over the genome.

Or, just as possible, what if you kept the first switch but lost another wire?

circuit4

This is an interesting change. Now, to light up the bulb, you have to close both the first and second switch. It also fits Behe’s description of an irreducibly complex system, because removing any part, the battery, the first switch, or the second switch, produces a pathway that cannot light up the bulb. It’s a dead system. It is most definitely irreducibly complex by any reading of Behe’s hypothesis.

But does that mean it could not have evolved by the incremental addition or subtraction of parts, with every step retaining the full capability of lighting up the bulb? Of course not. I just led you through each step, and in all four of the cartoons above, you can turn the lightbulb on. The fact of ICness does not vitiate the idea of incremental evolution.

So naive creationists will look at the fact of the organization of the eye, that you cannot remove the optic nerve or the retina and still have a functional eye, and fallaciously argue that that means it could not have evolved. This is logically false. I can point to lots of biological systems that can be called irreducibly complex: I am personally irreducibly complex, for instance, because I would stop functioning if you cut out my heart or gave me a brainectomy or deleted a big chunk of my immune system — but that fact is not sufficient to demonstrate that evolution couldn’t have done it.

I’ve been pointing this out to creationists for well over a decade, and all I ever get from them is stupefied stares and the occasional splutter. I don’t expect it will sink in this time, either. But I do derive a certain rude satisfaction from the fact that creationists repeatedly exhibit that same dumb incomprehension every time, so I’ll keep puncturing them with it.

Comments

  1. […] By PZ Myers […]

  2. […] By PZ Myers […]

  3. #3 Gregor Macdonald
    April 26, 2014

    You will rarely find any version of highbrow creationism that is not, at bottom, and argument from personal incredulity. I.C. is just another example. It roughly goes like this “the evolutionary explanation is too hard for me to believe, therefore, I choose to believe X instead.” It’s just another non-sequitor and it could be applied to any phenomenon from gravity to germs to structural engineering. “I find in the wonder of suspension bridges a distribution of weight along the cables and spans that cannot be explained by physics alone. ” And with that, you can immediately provide yourself a belief in the loving spirit that resides in the workings of bridges.

  4. #4 hells littlest angel
    April 27, 2014

    And at the bottom of that personal incredulity is the inability to grasp a time scale of hundreds of millions of years. This is why I have the tiniest, merest scrap of sympathy for those who reject evolution — human beings aren’t designed inclined by experience to understand the evolutionary time scale on anything beneath the intellectual level, so if intellect isn’t a significant factor in how you relate to the external world, you’ll have a tough time accepting evolution.

  5. #5 Tom Ozminkowski
    Rochester, NY, USA
    April 28, 2014

    HLA (#4) – That is the best response the use to the Personal Incredulity Fallacy I’ve ever heard. I hope you don’t mind if I steal, er, borrow it.

    TJOzzie

  6. #6 G
    April 28, 2014

    Hey PZ: I’m going to argue in favor of the Irreducible Complexity of religious fundamentalism. (Definition of fundamentalism: the belief that scripture is literally true in all details, with zero exceptions).

    To paraphrase you only slightly, “[fundamentalism] is falsified if you identify a pathway, for instance, that would not be functional if you removed a piece.” If you remove (falsify) any piece of the fundamentalist mythos, the basis for the entire belief system collapses.

    This is why fundamentalists fight like hell to force-fit everything into their account of the universe. If the universe appears to be older than 6,000 years, it must be that the deity has created e.g. the fossils, the red shift, etc., to test humans’ faith. (In psychological terms this is an example of “ideas of reference”, generically, “X exists or occurs _for the purpose of_ conveying a particular message or meaning _to me or to my social group_.” A more mild and common example is “that song speaks to my feelings about X”, and a textbook psychiatric example is “the TV news anchor-person is sending me coded messages.”).

    This is also why the vast religious mainstream has no problem with evolution. They recognize that bronze-age pastoralists, whatever wisdom they may have had about moral issues, were not biologists or astrophysicists. One shouldn’t turn to moral philosophers for answers about science, any more than one should expect science to provide answers to questions of values.

    By analogy, hitting a baseball requires your brain to do complex trigonometry at high speed. But you wouldn’t ask your baseball coach to teach you trig, nor would you ask your math teacher to coach you at baseball, and this state of affairs does not produce an existential catastrophe.

    Individuals whose nature hardwires them for belief in a deity can locate their deity’s primal creative action at some point before the Big Bang, and have no conflict with empirical science.

    If you remove a piece from any non-fundamentalist religious mythos, it doesn’t create an existential catastrophe for believers: they just make adjustments, e.g. “God’s intent works through evolution,” or “a ‘day’ in the mind of God is billions of ‘years’ to the lives of humans.” These types of propositions are as unfalsifiable as the existence of the deity itself, collected under the heading of “faith,” beliefs held in the absence of empirical evidence.

    Where this leaves rationalists & empiricists: We have no conflict with those for whom “faith” resides in untestable ideas and who specifically do not seek to impose upon public policy such as the teaching of science. Our conflict is with those who fight existential battles to impose untestable beliefs on others. If we draw the dividing line at that point, we win: religious moderates on the same side as rationalists & empiricists, status quo ante, separation of church and state, and the increasing marginalization of religious extremism.

    My working hypothesis is that “attitude toward the existence/nonexistence of deities” is determined by neurobiology in a manner analogous to sexual orientation, and this appears to have some empirical support. Hypothetically, if you remove the societal biases toward belief and against atheism and agnosticism, what you should see in a socially unbiased population is a curve describing the natural distribution of the population from “believe in deity” at one end, “don’t know or don’t care” in the middle, and “disbelieve in deity” at the other end. (Though, “don’t know” is not the same thing as “don’t care,” and these would have to be parsed out separately.

  7. #7 Southern Skeptic
    April 29, 2014

    “I am personally irreducibly complex, for instance, because I would stop functioning if you cut out my heart” lol, well put. I need to remember that one.

  8. #8 Janus M
    May 2, 2014

    http://www.evolutionnews.org/2011/03/michael_behes_critics_make_dar044511.html

    I haven’t read Behe or Dembski in a long while, and even I knew of the probabilistic nature of the argument from IC.

    Even if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitively rule out the possibility of an indirect, circuitous route…
    (Michael Behe, Darwin’s Black Box, p. 40 (Free Press, 1996).))

  9. #9 Tristan Roodt (14189004)
    Johannesburg, South Africa
    May 4, 2014

    A very refreshing and well-written piece. It is easy to descend into cynicism and spiteful arrogance when you are involved in debates such as “evolution versus creationism”, politics and a multitude of other controversial topics. Whilst Myers’ was definitely a bit subjective, it was factual and precise. We are all human after all, so bringing our ideals into our arguments is hard to avoid. I’m very much pro-evolution and I’m a strong advocate against blind creationist arguments myself, so I did enjoy the read that much more.

    Creationists argue with ideals and subjective impulses, but fiercely hold up “facts” and “empirical evidence” such as Irreducible Complexity to justify what is simply blind faith. Humans are emotional creatures and when they are wholly convinced of something they will often zealously defend it come hell or highwater.

    Are we “pro-science” invidivuals much different? Not really. We are zealously defending our faith too. The critical difference is… We agree to humble ourselves before the results of empirical results and tried and true theory. But all humans share this advocacy of our cause, whether it is justified (evolution) or not (the flying spaghetti monster).

  10. #10 Chuck Billo
    Canada
    May 8, 2014

    It’s important to mention here, that “belief” does not actually require facts. It’s not a good word for Scientists to use.
    We should use words that reflect the actual situation:
    It appears that…
    The conclusion is…
    We think that…
    All indications are that….
    As an estimate…
    I’d quickly guesstimate…
    The facts show….

    Just as ‘faith’ has *nothing* to do with Science, “belief” drags Science and Scientists down into some sense of erroneous equality with other, utterly ludicrous beliefs.

  11. #11 Jim
    May 8, 2014

    All creationists are reducible perplexities.

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