Where do we get the probabilities?

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asks Winston Ewert at UD.  For those of us who can’t post there, this thread is for us to respond here.  Winston himself is as ever, cordially invited to join us, as are any UD commenters.

What is the probability of a structure like the bacterial flagellum evolving under Darwinian processes? This is the question on which the entire debate over Darwinian evolution turns. If the bacterial flagellum’s evolution is absurdly improbable, than Darwinism is false. On the other hand, if the flagellum is reasonably probable than Darwinism looks like a perfectly plausible explanation for life.

Dembski’s development of specified complexity depends on having established that the probability of structures like the bacterial flagellum is absurdly low under Darwinian mechanisms. Specified complexity provides the justification for rejecting Darwinian evolution on the basis of the absurdly low probability. It does nothing to help establish the low probability. Anyone arguing the Darwinian evolution has a low probability of success because of CSI has put the cart before the horse. You have to show that the probability of the bacterial flagellum is low before applying CSI to show that Darwinism is a bad explanation.

So what is the probability of a bacterial flagellum under Darwinian mechanisms? Obviously, we can’t expect to know the exact probability, but can we at least determine whether or not its absurdly improbable? That’s the question on which the whole debate rests. It seems that any arguments over Darwinism should be focused on arguments about this probability. It is the key to the whole discussion.

Intelligent design proponents have long offered a number of arguments attempting to show that Darwinian evolution accords a low probability to structures such as the bacterial flagellum. Darwin’s Black Box argues that irreducible complexity is highly improbable to evolve. The Edge of Evolution argues that non-trivial constructive mutations are too improbable for Darwinian evolution. Doug Axe’s protein work argues that protein evolution is too improbable. The fact is, almost every work by intelligent design proponents has been directed towards arguing that Darwinian evolution is too improbable to work. There is no mystery about why we intelligent design proponents think that evolution is improbable.

Intelligent design critics are going to dispute all of these arguments I mention. That’s fine. But dispute those arguments. Don’t act as though we’ve never given explanations for why we think that Darwinism is an improbable account of the complexity of life. Don’t attack specified complexity for not showing that Darwinism is improbable. That was never the intent of specified complexity. It is the intent of a host of other arguments put forward by intelligent design proponents.

Arguing over who has the burden of proof might be ok if there were no arguments on the table attempting to establish that question. But there are arguments on the table. There is no need to fall back on trying to shift the burden of proof onto someone else. Its a dubious tactic at the best of times, and totally pointless in the face of the arguments developed by intelligent design proponents.

So please, discuss the actual arguments put forward about the probabilities.

222 thoughts on “Where do we get the probabilities?”

  1. Rumraket: They’re not contradictory. There can be multiple routes to the same destination. Evidence for one model does not “contradict” another model. That doesn’t make sense.

    RNA first it is not contradictory with protein first? RNA world isn´t contradictory with metabolism first? Starting with membranes is not contradictory to start in hidrotermal vents?

  3. Blas: RNA first it is not contradictory with protein first? RNA world isn´t contradictory with metabolism first? Starting with membranes is not contradictory to start in hidrotermal vents?

    Perhaps you should point out the correct path to follow, so that all other paths can be dropped?

  4. Blas: RNA first it is not contradictory with protein first? RNA world isn´t contradictory with metabolism first?

    No. Finding evidence for one does not mean the other could not happen. There’s a difference between answering the question “what did happen at the origin of life?” and “how could life originate?”

    Blas: Starting with membranes is not contradictory to start in hidrotermal vents?

    No.

  5. thorton: Endothermic reactions do create more complex molecules from less complex ones all through naturally occurring processes.Looks like Lizzie was right and you are wrong.

    Can you give me an example? petrushka give a link where a natural process led to less complex RNAs, can you give an example of your statement?

  7. Blas: To be published needs to be “positive results”.

    That’s a common complaint.

    Perhaps you can link to a paper that is fraudulent.

    Again, people speculate on OOL. Do you have a citation to anyone who claims to have discovered the correct and true history of OOL?

  9. Blas: Well if the other universe affected phisically this universe it is not other universe is another part of this universe.

    I’m afraid you don’t understand what is meant by the term multiverse then.

  10. Rumraket: I’m afraid you don’t understand what is meant by the term multiverse then.

    Off course! Darwinists sure have two meaning for the word universe and two for the word multiverse. All ready for the old darwinian trick.

  11. petrushka: That’s a common complaint.

    Perhaps you can link to a paper that is fraudulent.

    Again, people speculate on OOL. Do you have a citation to anyone who claims to have discovered the correct and true history of OOL?

    http://www.economist.com/news/leaders/21588069-scientific-research-has-changed-world-now-it-needs-change-itself-how-science-goes-wrong

    http://www.theguardian.com/science/2011/sep/05/publish-perish-peer-review-science

    As I say do not expect darwinistt have a look to the real world.

  12. Blas: Off course! Darwinists sure have two meaning for the word universe and two for the word multiverse. All ready for the old darwinian trick.

    It really doesn’t matter what you call it Blas, there is either evidence for a multiverse model or there is not. Different models predict different kinds of evidence to look for. That you personally think if one cosmic expansion physically affects another, then they’re part of the same universe doesn’t change anything. That’s really just you changing the goalposts out of fear.

  13. Blas,

    You’ve accidentally posted the wrong links, Blas. These are about science in general, not your specific claims.

  14. Neil Rickert:
    Mathematician Jason Rosenhouse has a nice analysis of Ewert’s UD post:
    Another Round on Probability and Evolution

    Thanks for the link. Funny that he says:

    … I have just read an astonishingly bad post over at Uncommon Descent that discusses this issue, and I cannot resist responding.

    The post is called, “Where Do We Get the Probabilities?”

    Looks to me like a perfectly typical, expectedly stupid post over at UD. I mean, when almost every post at UD is equally, predictably, bad, it kinda takes the astonishment out of encountering yet another wad of their nonsense, doesn’t it?

    It’s interesting to read him taking down the coin-flip analogy:

    To see the problem, let’s use a standard example. The specific sequence of H’s and T’s that arise in five hundred flips of a coin is exceedingly unlikely, but that is not necessarily suspicious since something had to happen. But five hundred heads would be suspicious, roughly because it conforms to an easily describable pattern. ID folks try to extrapolate this sort of reasoning to structures like the flagellum. It’s not only improbable, they say, but it’s “specified” by virtue of its functionality.

    But this argument doesn’t work at all, and for a simple reason. When we reason about what is, and is not, likely to occur when flipping a coin, we have a good grasp on the relevant probability space. We generally take it for granted that we are talking about a fair coin tossed in a fair way, meaning we are justified in equipping the space with a uniform probability distribution. That is precisely what we can not do when we are discussing genetic evolution. In this case we have no way of determining the correct distribution to apply to the space.

    I wonder if the UDists will post a dozen more threads on why coin flips mean random evolution can’t work just to prove that they totally miss the point.

  15. Blas,

    Blas: No, we are tired to be fooled with answers that only fit with metaphisical positions.

    Me: So you think the gradual generational change in a lineage – which happens, whenever you have a lineage – is being proposed to fool you, and is non-empirical?

    Blas: No the old darwinian trick. I said I mean evolution as the theory that said that a bacteria become a whale buy ramdom mutations, not the change on alele frequency.

    No trick, Blas; no need to be so shitty. You never even mentioned bacteria or whales, just some vague whingeing about metaphysics. Small amounts of change aren’t metaphysical. Large amounts are. Got it. Thanks for your time.

  17. Blas: Can you give me an example? petrushka give a link where a natural process led to less complex RNAs, can you give an example of your statement?

    Photosynthesis

  18. Richardthughes: http://scienceblogs.com/evolutionblog/2014/02/04/another-round-on-probability-and-evolution/

    Jason Rosenhouse says:

    To see the problem, let’s use a standard example. The specific sequence of H’s and T’s that arise in five hundred flips of a coin is exceedingly unlikely, but that is not necessarily suspicious since something had to happen. But five hundred heads would be suspicious, roughly because it conforms to an easily describable pattern.

    Why would it be suspicious? All sequences have the same probability.

  19. Evolution includes both random mutation and natural selection. Any probability calculation that does not include the effects of natural selection is obviously not a good model for evolution as a whole. Many, if not all, of the probability calculations touted by the ID side suffer from this defect; they do not include the effects of natural selection.

    I have tried to make a start on a calculation that does include natural selection, which is too long to post here, but can be read at The Evolution of Boojmase. While that piece is not explicitly about the bacterial flagellum, it suffices to show that the inclusion of natural selection has a major impact on the probabilities, increasing the chances in the given scenario by over 120 orders of magnitude, from 6.35e130 years to 2.01e6 years to evolve a 100 amino acid protein.

  20. coldcoffee,

    Any individual sequence has the same probability as any other. However, more sequences will tend towards the expected 50% H/T split than would depart substantially from it. If a particular trial departs far from expectation (which means you must know the distribution) you’d be suspicious.

  21. rossum:
    Evolution includes both random mutation and natural selection.Any probability calculation that does not include the effects of natural selection is obviously not a good model for evolution as a whole.Many, if not all, of the probability calculations touted by the ID side suffer from this defect; they do not include the effects of natural selection.

    I have tried to make a start on a calculation that does include natural selection, which is too long to post here, but can be read at The Evolution of Boojmase.While that piece is not explicitly about the bacterial flagellum, it suffices to show that the inclusion of natural selection has a major impact on the probabilities, increasing the chances in the given scenario by over 120 orders of magnitude, from 6.35e130 years to 2.01e6 years to evolve a 100 amino acid protein.

    That’s a very nice demonstration of how results are contingent on actual evolutionary mechanisms, as opposed to the usual creationist straw man misconceptions.

    While I hope that makes the flaws in some common intelligent design creationist probability calculations clear, I suspect that your seventh assumption:

    7 The effectiveness of a boojumase at digesting boojums is equal to the percentage of effective amino acids it contains. Thus since
    normal snarkase has 5% effective amino acids it can digest 5% of
    boojums during their passage through the mome rath’s gut. A boojumase with 20 effective amino acids would be 20% effective and would digest
    20% of boojums and so forth.

    will be responded to with cries of “Irreducible complexity! Irreducible complexity!” followed by the burying of faces in holy books.

    Neutral drift and exaptation would be interesting extensions to address the “Prove that every step was beneficial (but don’t ask us to prove that our omnipotent, omniscient, omnibenevolent designer exists).” gods-of-the-gappers.

  22. coldcoffee: Jason Rosenhouse says:

    To see the problem, let’s use a standard example. The specific sequence of H’s and T’s that arise in five hundred flips of a coin is exceedingly unlikely, but that is not necessarily suspicious since something had to happen. But five hundred heads would be suspicious, roughly because it conforms to an easily describable pattern.

    Why would it be suspicious? All sequences have the same probability.

    “500 heads would be suspicious” isn’t a statement about the sequence of flipped coins; rather, it’s a statement about how humans respond to that sequence of flipped coins. For whatever reason, we humans tend to attach more significance to an all-heads sequence than to a sequence which has more-or-less equal numbers of heads and tails. Why do we humans do that? I dunno, myself. But I’m pretty sure that whatever the reason (or reasons) may be for us humans to attach a high degree of significance to an all-heads sequence, that reason (or reasons) has a whole lot to do with human psychology, and not much at all to do with probability.

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