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The “Tornado in a Junkyard” fallacy

by Donald Prothero, May 09 2012

When you hear creationists argue their cause, sooner or later they reach into their standard litany of debunked arguments. One of their favorites (since it sounds convincing to their largely math-illiterate followers) is to point to the complexity of a molecular system or the cell or any other part of nature and “how could such a complicated system arise BY CHANCE?” The bigger implication is that they cannot fathom humans and their religious worldview being produced by anything other than a supernatural creator, so chance (as they misunderstand the concept) cannot produce it. The same argument underlies much of what the “intelligent design” creationists claim as well.

There are many versions of this argument, all of which are equally fallacious. When I debated Duane Gish at Purdue University in 1983, he was using his favorite line of his whole spiel, stolen from the maverick astronomer Fred Hoyle (legendary for being wrong on nearly every thing he argued, including Big Bang cosmology and his attacks on Archaeopteryx and evolution). In Gish’s version, he argues that the probability of random evolution assembling the complex system of life was as likely as a tornado in a junkyard assembling a Boeing 707 (which shows how ancient this punchline was).

As in the case of all creationist arguments, this one is completely fallacious on several different levels:

1. Evolution is not “random chance” like a lottery or throwing the dice. The variation on which natural selection works (mutations, recombination, etc.)  is randomly produced, but natural selection is not random. Natural selection is a process that weeds out unfavorable variations, and greatly improves the likelihood of events.  Anti-evolutionists for years  have used various versions of this fallacious analogy: “what is the probability that a monkey (or chimpanzee) with a typewriter randomly pounding on the keys could produce the works of Shakespeare?” A better analogy is a monkey with a word processor, whose program (like your spell checker) automatically deletes or fixes mistakes, so that even by typing random keys, the monkey will eventually assemble a recognizable string of words. Richard Dawkins (in The Blind Watchmaker, 1986, and Climbing Mount Improbable, 1996) has provided many interesting examples and computer models that show just how easily this can be done. This is the fundamental misunderstanding: evolution is not just “random chance” but a strong non-random force capable of changing genomes and acting upon material provided by chance.

2. Many of the standard examples that creationists trot out seem staggeringly difficult to produce as they present it, but in fact there are numerous small intermediate steps that show it’s not so hard as they imagine. As I discuss in Chapter 6 of my evolution book, since the days of the Miller-Urey experiment in 1953, most of the chemical steps needed to assemble the simplest forms of life (RNA in a lipid bilayer membrane) have all been produced by biochemists in the laboratory using relatively simple chemical reactions. To produce long-chain biochemicals, there are a number of “templates” (clays, zeolites, pyrite, etc.) that assemble simple organic chemicals into long-chain polymers by lining them up all close together, and then their chemical linkages form. (I use the analogy of a mosh pit—everyone packed shoulder to shoulder tightly in the same direction, then their earrings and piercings get  hooked together). As Lynn Margulis and others have shown, the eukaryotic cell can be most easily produced by endosymbiosis, where symbiotic prokaryotes like cyanobacteria and purple non-sulfur bacteria have changed to organelles like chloroplasts and mitochondria. With all these intermediate steps that have been discovered in the past 60 years, the origin of life from simple chemicals is no longer as improbable as the creationists like to claim.

3. As anyone who really understands probability knows, you can’t make a probability argument after the fact. If you do so, then any complex sequence of events is extremely improbable, even though they actually occur. A good analogy is the one I used in the Gish debate. I asked the audience of several hundred to estimate the probability after the fact that all of the events that had happened in their lives would actually happen, and the probability that among all those unlikely events, they would all end up in this room at this particular moment. Naturally, the improbability of this event is enormous. I pointed out to the audience that by Gish’s probability arguments, they could not exist! For someone to make a probability argument of this sort, it has to be made ahead of time, because life is full of events that (looked at after the fact) are extremely improbable—yet happened nonetheless.

So the next time you get into an argument with a creationist, don’t let them baffle you with garbage about “random evolution” or “the probabilities say it is impossible”.

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30 Responses to “The “Tornado in a Junkyard” fallacy”

  1. Other Paul says:

    Given four gigayears of speciation, we’ve ended up with this particular set of species at this particular point in spacetime. Now choose a method to decide how many members there are in that set. It doesn’t really matter which, as long as you agree to keep using it. Let’s say the answer’s ten million.

    It should be moderately graspable by anybody familiar with time-travel fiction and the history-altering stepping-on-a-butterfly trope – one that even an intelligent-designerist could find agreeable – that the chances of the same outcome with slightly different starting conditions (even assuming a deterministic model of biogeneration) would be incredibly tiny.

    Does anyone out there have any idea how many ways that, given four gigayears of purely random speciation, ten or so million species – of whatever biological constitution – might arise? Presumably the combinatorial explosion would be enormous, easily dwarfing a, then, relatively tiny number like ten million into invisibility. Wouldn’t this argument have to work with those who take a hard-line random position, hoist by their own petard as it were?

    (Always assuming the person you’re arguing with isn’t allowing you only six thousand years, that is).

  2. Trimegistus says:

    Interestingly, one sees the same argument presented with an absolutely straight face in discussions of astrobiology: the “Rare Earth Hypothesis.” The argument goes that all the things which had to happen to produce life on Earth and our glorious selves are so unlikely that no other intelligence can possibly exist in the Galaxy.

    My favorite analogy to show why this argument (and by extension the Creationist one described above) is a fallacy is lotteries: the odds against any lottery ticket being the winner are astronomical. But people win the lottery every day. Because one particular ticket doesn’t have to be the winner — just some ticket somewhere. We are a winning ticket but of course we never see the losers.

    • starskeptic says:

      …like a winner saying that it’s so improbable that he didn’t, in fact, win…

      • Pepper1967 says:

        Could be extended to the probability for birth itself.
        mom and dad copulated 200 times of which i was only 1 sperm out of 20 million. odds are then multiplied accordingly. = astronomical odds that id be here at all. but yes – as above when you speak of ‘how lucky one is’ you neglect all the ones that had to die (or lose) so i could be here.

  3. tmac57 says:

    The idea that a complex entity needs to have a creator/designer,when taken to its ultimate extrapolation,does not turn out well for those who believe this to be true.They are better off saying “I believe because that’s what I want to believe” rather than trying to find a rational argument for their belief.

    • Janet Camp says:

      I was taught by a wise undergrad professor to not bother arguing with faith, because the two are simply incompatible to begin with. Evidence seems to show that no matter how many facts you present to people wish established “beliefs”, they do not change their minds–and yet, we all probably know someone who has, indeed, given up some cherished belief following some good skeptic-fuelled investigation. It does happen, but like the lottery, not often.

      • tmac57 says:

        The person has to be willing to intellectually engage in the question of the truth of something,before they can change a deep seated belief.It’s tough,but not impossible.

    • Beatrice says:

      “the eukaryotic cell can be most easily produced by endosymbiosis, where symbiotic prokaryotes like cyanobacteria and purple non-sulfur bacteria have changed to organelles like chloroplasts and mitochondria.”

      tmac . . . is the above scientific foreplay? No wonder scientists had to create Viagra.

      Here is the simple version of Creation. The Universe or “Oneness” sprang forth from itself a lover and these two energies got busy . . . the male active principle and the the female receptive principle have been making love ever since. The progeny of this cosmic passion sprang forth as the material world which is constantly evolving and there is great intelligence behind the creation we call Earth.

      There is both intelligent design and evolution and it’s a beautiful thing.

      • Autumn says:

        Really? So what are the male and female portions of the nuclear burning of stars? How, exactly, does your balderdash explain the breaking of the symmetry of the four fundamental forces? Or the physics of spacetime near an event horizon?
        Your “beautiful thing” is about as beautiful, and as useful, as the “Great Green Arkelsiezure” theory.

  4. Tom Nottle says:

    You may be right or you may be wrong in your conclusion. But your condescending attitude toward those who differ from you is most certainly in error. You do not win an argument by putting down your opponents. Be logical, put down their facts. That way you have a chance to win.

  5. Don says:

    I agree with Prothero’s point #3, but unfortunately many people interpret the extreme unlikelihood that their life path took them to a particular moment as PROOF that a higher power was behind it! (i.e. “everything happens for a reason”)

    • Max says:

      The question is if everything happens for a reason, why does it look like it happens by chance?

  6. BKsea says:

    A good extension of the “throwing the dice” analogy might be the game of Yachtzee where you have 3 rolls to get the same number on all 5 dice. If you simply roll all 5 dice 3 times (akin to the tornado in the junkyard) your chance of winning is 1/432. If instead you build on each roll, for example by keeping an existing pair from the first roll, your odds improve 20-fold to 1/22. This building on past success is how evolution works.

  7. Pete says:

    Don (#4), there is an old stock fraud that goes like this:
    1) Pick 100 rich marks, and present yourself as a market expert – and you’ll give them a free test of your ability.
    2) Pick a stock that you think will shift in the near future
    3) tell half of the marks it will go up in a month, and the other half that it will go down.
    4) Once it does shift, take the half that you told the right thing to, and repeat steps 1-4 4 times.
    5) now you have 3 people who think you can predict the market. Get them to give you their money to invest, and take off.

    That’s a good example to use when people go that route.

    • tmac57 says:

      Even 3 out of 4 correct might be enough to sway them.In other words,people will see what they WANT to be true.

  8. MadScientist says:

    Ah, the 707 – perhaps the only heavy aircraft to have been subjected to a barrel roll.

    I never cease to be annoyed by creationists’ bad analogies. Come to think of it – I have yet to see a Good Analogy and I generally tell people “there are bad analogies and worse analogies”.

    • Max says:

      So analogies are like romantic comedies :-)

      But seriously, I like analogies for logical fallacies, since different arguments can commit the same fallacy. For example, take the argument that “X is safe because I use it and I’m still alive.” If this argument is valid, it should apply to any X that doesn’t kill you quickly, so I substitute tobacco for X. But this usually goes over people’s heads, and they think I’m saying X is as bad as tobacco.

      • tmac57 says:

        It can be really frustrating when trying to explain to someone that although they may have come to a correct conclusion,that they got there using fallacious reasoning.To them,if they got the right answer,then they must have been thinking clearly.

    • Kerry Lynch says:

      Hi Mr MadScientist, this entire article is full of bad analogies, read my post below for examples. But analogies aside, when was evolution proven, what date?(I don’t expect an answer, because their isn’t one.) Even if you could show me proof of evolution that doesn’t prove there is no God. And doesn’t answer the question of where did matter come from.

      • Paul Johnson says:

        A gentle reminder. Science does not attempt to prove anything … it cannot. It only attempts to find the most plausable explanation given the observable facts. If further facts come to light that contradict their explanation (even a well established theory), they must adjust their conclusion to include the new facts.

      • tmac57 says:

        Certainly,science cannot prove that “there is no God”. And religion cannot prove that ‘God’ exists,or that ‘God’ created matter. But science does seem to be doing a pretty good job of untangling the ‘mysteries’ of our universe,one small step at a time,with no end in sight,while religion is still wedded to an ancient, fixed idea of what we are,and how we got here, that does not differ substantially from what they themselves might regard as another religion’s ‘myths’.

  9. John K. says:

    A fine argument against spontaneous generation, but not much to do with evolution.

    Probabilities are always so tragically abused. Probabilities are mostly about unknowns, so a low probability means a lot of unknowns. If the paths of the lottery balls are completely known, the “chances” are not the same at all.

    If the probabilities are next to zero, it is an indication that the information applied does not predict the event, not that the event is impossible. Beware of those who would present probabilities without specifying the calculations for the divisor.

    • MadScientist says:

      Yeah, and yet spontaneous generation is just what they believe – it’s as if some god just walked past the earth and instantly created humans.

  10. Kenneth Polit says:

    The fact that there are people that actually believe this nonsense doesn’t bother me nearly as much as the fact that they don’t even care if what they believe is even true. They believe this crap because it makes them feel better or special. I just can’t wrap my head around the idea that some people actually take pride in being willfully ignorant. That’s what creationism is by the way, willful ignorance.

    • Tim says:

      Willful ignorance? I think it is called confirmation bias. It is present in both religious ans scientific realms when interpreting evidence. In both cases, truth is not always paramount.

  11. cheesehead says:

    About #1. The issue I always have with this comparison is that someone had to write the word processor/algorithm which implies a higher power guiding the outcome.

  12. Kerry Lynch says:

    Hi Mr.Prothero, though your arguments “sound” intelligent your analogies are off and don’t directly answer the question. As to your monkey analogy, even with a word processor a monkey couldn’t produce a work of Shakespeare or anything intelligible for that matter. That was the question, not a string of words. And even if the the monkey could produce something understandable, it would be the word processor not the monkey that actually produced the work. And as for the people appearing in the room, again your conclusion is off. Just because they may not end up in that room “does not mean they wouldn’t exist”. They would just be somewhere else.

    To every person who believes in evolution. When did this so-called “proof” occur? What DATE was evolution proven? I somehow missed that headline.

  13. K Lynch says:

    Moderator, why was my post not displayed? If you see the lies people publish about evolution why do you participate in spreading them. Hiding my post won’t hide the fact that evolution hasn’t been proven.

  14. gdave says:

    @Kerry Lynch:

    You seem to be insisting on a false dichotomy. Scientific theories simply do not exist in a binary proven/not-proven state. They exist in a continuum of how confident we can be that they can accurately describe and predict the world around us.

    There is no specific date on which Newton’s Laws were “proved”, but we can be very confident that they can and will accurately describe and predict the motion of bodies in our ordinary frames of reference. Nor is there any date on which General Relativity, the Laws of Thermodynamics, the Heliocentric Model, or any other scientific theory, law, or fact was “proved”. Instead, there has been a growing accumulation of evidence for all of these, to the point where we can now be highly confident that they can and will accurately describe and predict how the world around us works. And the same is true for the Modern Synthesis of evolutionary theory.

    Please note that nowhere in his post does Dr. Prothero refer to “proof” or to evolution having been “proven”. It is you who are referring to “so-called proof.”

    And, by the way, I don’t think it’s quite accurate to say that I “believe in” evolution. I accept that the overwhelming mass of evidence (literally, in the case of the fossil record) indicates that it is the most accurate and useful description we currently have to explain the diversity of life on Earth. If new evidence were to come to light that contradicted modern evolutionary theory, I would become increasingly less confident in its accuracy and predictive power, and conceivably I could become highly confident that it is just plain wrong, or not even wrong, but there would be no date on which it would suddenly flip from “proven” to “un-proven” or “disproven”.