Cornelius Hunter vs William Dembski?

Cornelius Hunter has posted an odd argument:

Is there evidence for evolution? Sure, there is plenty of evidence for evolution. But there are significant problems with evolution. There is plenty of evidence for evolution just as there is plenty of evidence for geocentrism. But the science does not bode well for either theory.

So the evidence for evolution follows this general pattern: Even at its best, it does not prove evolution to be a fact. And furthermore, the evidence reveals substantial problems with evolution.

So how can evolutionists proclaim evolution to be a fact with such fervor? There seems to be a glaring mismatch between the evidence and the truth claims of evolutionists. The answer is that evolutionists use contrastive reasoning. Evolution is not claimed to be a fact based on how well it fits the evidence, but rather on how poorly the alternative fits the evidence. Evolution is proved by the process of elimination.

In other words, Hunter is arguing directly against Dembski:.

In eliminating chance and inferring design, specified complexity is not party to an argument from ignorance. Rather, it is underwriting an eliminative induction. Eliminative inductions argue for the truth of a proposition by actively refuting its competitors (and not, as in arguments from ignorance, by noting that the proposition has yet to be refuted)

Now, in my view, both Hunter and Dembski are wrong, but Hunter is not wrong because of Dembski’s argument, and Dembski is not wrong because of Hunter’s argument, or at least, not as it stands.

Hunter objection to “contrastive reasoning” is based on two misunderstandings, as far as I can see.  The first is of the very text he quotes to support his argument, namely Eliott Sober’s Evolution and Evidence:

This last result provides a reminder of how important the contrastive framework is for evaluating evidence. It seems to offend against common sense to say that E is stronger evidence for the common-ancestry hypothesis the lower the value is of [the probability of E given the common-ancestry hypothesis]. This seems tantamount to saying that the evidence better supports a hypothesis the more miraculous the evidence would be if the hypothesis were true. Have we entered a Lewis Carroll world in which down is up? No, the point is that, in the models we have examined, the ratio [the probability of E given the common-ancestry hypothesis divided by the probability of E given the separate-ancestry hypothesis] goes up as [the probability of E given the common-ancestry hypothesis] goes down. … When the likelihoods of the two hypotheses are linked in this way, it is a point in favor of the common-ancestry hypothesis that it says that the evidence is very improbable.

(Hunter’s emphasis)

In a related thread, Hunter wrote, in response to a comment of mine:

So you can see that according to the likelihood ratio, the argument for CA strengthens as p becomes smaller. And as p becomes smaller, the conditional probability for CA also becomes smaller.

In other words, the worse the probability for CA, the better the case for CA, because the SA probability got even worse yet.

The context here is that Sober is considering a scenario in which two species share the same genetic sequence, and comparing the hypothesis that the species share a common ancestor (“CA”) with the hypothesis that they have a separate ancestry (“SA”).  He shows  how the relative probability of these two hypotheses depends on the probability of  the sequence arising spontaneously (“p”).

As I try to explain in my response to his comment, Hunter seems to have confused the probability for the data, given the hypothesis, with the probability of the hypothesis, given the data.  The former indeed goes down as p goes down.  However, as p goes down, the latter goes up.  This seems to be a simple error on Hunter’s part, but it is an important one as it goes to the heart of his argument: the reason that the posterior probability of CA given the data goes up relative to the prior for CA, and therefore also relative to the posterior for SA, is that p(SA)=1-p(CA).  If ancestry is not common then it is separate.  There is no excluded middle.

Hunter has failed to note that in the case of a pair of hypotheses in which one is the null of the other, as the posterior probability of one goes up, the posterior probability of the other goes down; in this case, therefore, “contrastive reasoning” is completely valid, and Sober is right that if we find a sequence in two species with a very low p, that is extremely strong evidence that the hypothesis that they common ancestry is correct – the posterior probability of CA will approach 1, and the posterior probability of SA will approach 0.

He then asserts that Sober’s logic is applied (either by Sober or by some evolutionist unspecified) to a piece of reasoning in which there is an excluded middle:

Science cannot know all the alternative explanations for the origin of the species. When evolutionists conclude evolution is a fact via the process of elimination, they are making a subtle but crucial non scientific assumption—that they know all the alternative explanations.

But here, we are not comparing “Common Ancestry” versus “Separate Ancestry”, where p(SA) must = 1-p(CA), and we know the probability of the data, given SA, but Evolution against Not Evolution, where we simply cannot estimate the probability of the data given Not Evolution, because we cannot know what those those Not Evolution hypotheses are.  Of course, even in Sober’s example, if the “SA” hypothesis includes a maverick God who inserts odd sequences into his critters for no good reason (Hunter postulates a deleterious one), then our calculations of the probability of the data given SA will be off, but this is not the point Hunter makes.

So IMO, Hunter has misunderstood Sober, and has also misunderstood evolutionist claims, but is nonetheless right to say that you cannot infer that a hypothesis is correct, merely because it explains the data better than any other hypothesis on the table.  There may be a better one round the corner right now, and indeed, AFAIK, evolutionary scientists regard all evolutionary hypotheses as provisional, because that is pretty well the core of the scientific methodology – that all hypotheses are potentially falsfiable by a better one.

And that’s what makes Dembski wrong. All the arguments of Dembski’s I have read for inferring design assume that he has specified his null in such a way that the only alternative is Design.  For Dembski, 1-p(Not-Design) =  p(Design).  Which would be fine if he actually calculated p(Not-Design|data).  But he doesn’t.  He calculates the probability of a  very specific Non-Design hypothesis, given the data, which is not the evolutionary hypothesis, nor is it Design.  In other words, he excludes an enormous middle, and Hunter would be absolutely right to reject Dembski’s inference as fallacious, by exactly the same reasoning as he rightly rejects the straw man claim that evolution is true because it has a greater probability of being correct than any possible alternative.

That is certainly fallacious, I agree.  I look forward to seeing Hunter’s next post on how Dembski’s arguments are similarly fallacious ;)

 

 

12 thoughts on “Cornelius Hunter vs William Dembski?

  1. Cornelius Hunter has posted an odd argument

    Hunter specializes in odd arguments.

    Hunter: So the evidence for evolution follows this general pattern: Even at its best, it does not prove evolution to be a fact.

    Hunter does not understand science.  The evidence never proves a theory to be a fact.

    So how can evolutionists proclaim evolution to be a fact with such fervor?

    That’s just the way people talk.  Scientific theories are never proved as fact, but if the theory works well, people refer to it as fact.  Hunter appears to be objecting to the pragmatism of science.

    Dembski: Eliminative inductions argue for the truth of a proposition by actively refuting its competitors (and not, as in arguments from ignorance, by noting that the proposition has yet to be refuted)

    That’s an even worse misunderstanding of science.  Dembski is aiming to refute evolutionary theory, and assumes that such a refutation will provide evidence for ID.  But science doesn’t work that way.  In order for Dembski’s method to work, he would first have to show that ID is a legitimate competitor to evolution, though in its present form it obviously isn’t that.  And then he would have to identify all of the other possible competitors (there could be infinitely many of them), and refute those too.  Dembski’s scheme is unworkable.

    In my opinion, both Hunter and Dembski demonstrate that they do not understand how science works, though they disagree on how they misunderstand science.

  2. “In my opinion, both Hunter and Dembski demonstrate that they do not understand how science works, though they disagree on how they misunderstand science.”

    This raises an interesting puzzle for me. OK, we know that the findings of science have in many ways flat refuted non-negotiable doctrines of Dembski and Hunter’s religious faith. Therefore it can’t be right, and MUST be misrepresented as a creationist imperative.

    But what I can’t figure out is whether the misrepresentation is deliberate, or whether their strawman versions of science are their sincere best understandings of how science works, given the mental constraints they labor under in trying to figure it out.

    Or perhaps it’s a little of both. Hunter isn’t just confused by the vernacular, he’s making a clear category error, confusing a body of observations with an interpretation of those observations. The explanation for facts are obviously not the facts themselves!

    But Dembski’s error strikes me as less excusable. Maybe Hunter really doesn’t understand the difference between an observation and an interpretation. But surely Dembski knows that just because 2+2 doesn’t equal 22, that doesn’t mean it must therefore equal 42. And even if his religious faith blinds him to any explanation but his own, the logical error of eliminating an infinity of possibilities has been shown to him countless times – and he’s ignored this exactly that many. So I think he DOES understand, but doesn’t care to face the consequences.  

    Still and all, I can’t entirely rule out the possibility that when such devout beliefs are so unambiguously refuted by reality, the mind goes into a sort of shock. They can’t be right, they can’t be wrong, they MUST be one or the other, RESET, repeat, oops, RESET, etc.        

  3. But what I can’t figure out is whether the misrepresentation is deliberate, or whether their strawman versions of science are their sincere best understandings of how science works, given the mental constraints they labor under in trying to figure it out.

    I give them the benefit of the doubt, and assume that they are being honest.   But I admit that I cannot understand what kind of thinking they could be using.  My best guess is that a strong desire for ID to be true is inducing serious cognitive biases.

  4. Neil,

    You do realize that you could just step forward and demonstrate that your position is scientific- you know actually lead by example.

    The reason I say that is it is obvious that evos do not understand how science works and it is obvious that science does not support your claims.   

    So how about it? Can you lead by example or just bloviate?   

  5. There is a close relationship between the failure to understand the summation of probabilities ( p(a) + p(not-a) = 1) and one of the most basic facts of Natural Selection (f(a) + f(not-a) = 100%. For all that ‘negative’ selection dilutes a population in a detrimental characteristic, it enriches it in its less-detrimental alternative. One sees the fallacy again in characterisation of mutation frequencies – if most mutations are detrimental, then there aren’t any beneficial ones – but again, f(detrimental)+f(neutral)+f(beneficial) = 100%. As long as the first two frequencies do not add up to 100%, adaptation will proceed.

    Slightly less clearly related is the impact of the Law of Large Numbers in driving population change, and on the long-run signal of adaptation over the short-term noise of sampling – but again, it ain’t that hard to get a handle on. 

    These, particularly the first 3, are simply more formal mathematical expressions of some pretty basic logic. They are inescapable as ‘regularities’, Laws of Nature. And even a mathematical thicko like me can get it. So I really scratch my head sometimes. What is it that persuades someone to pretend that these very fundamental regularities disappear, when we consider the biological world? Or have only a minor role to play?

    Anyway, back to the OP: I look forward to watching Joe defend them both. 

  6. Elizabeth [and Flint],

    Interpretation of probability — distinction of credence and chance — is essential here. Sober (Bayesian) addresses relative degrees of belief in explanations, given the observations. Dembski (Fisherian) claims to address the chance of the observation (“hitting the target”), given the explanation.

    There are various errors in Dembski’s argument from specified complexity, a species of argument from improbability (low chance). I’m inclined, nowadays, to focus on the gross defect it shares with all arguments from improbability, namely meaningless reference to the chance (<1) of the outcome of an unobserved, and hence irreproducible, process.

    [I’m the guy who persuaded Dembski, late one night at UD, to admit that the explanatory filter was dead. Of course, he came back the next day to assert that the EF was the “best thing since sliced bread.” Years before, I had explained to him in email how he misunderstood the NFL theorem, and he had replied, “OK, but don’t expect me to admit to that.” I believe that Dembski knows that CSI is unsalvageable, but knows also that (a) make-weight is very useful in arguments that there is a growing body of scientific work in IDC; (b) the acolytes vest faith in his authority, and cannot cope with fallibility; and (c) his old books would not sell so well if he acknowledged that they are outdated.

    Lizzie, knowing that even if you were not like me in a certain way, your work would leave you only a limited amount of attention to give to IDC, I’m inclined to nudge you toward contemporary arguments by leading proponents. If you’re interested in deconstructing the mythopoeic processes at UD, all I can say is that the further you walk into the thicket, the more tangled it gets.]

  7. Tom,

    Strange with all that said that you still cannot produce a positive argument for your position. No equations, no formulas, no positive evidnece and no testable hypotheses. 

  8. I must agree with Joe G.  Clearly, the only people with a true understanding of science are those with the word “science” in their degree program, which is to say that a Bachelors of Science in, say, Electronics Engineering, makes one a true scientist, while one with a Bachelors of Science in, say, Physics, is not a real scientist.

    Or something. 

  9. Hunter has a history of making rather ridiculous claims, and I am frankly surprised that anyone really cares what he claims.
    I really had hoped that his getting caught doctoring a picture of a gray wolf, calling it a Thylacine, then using it to show how similar the two looked would have convinced even those that support his position that he is at best an unreliable source.
    Worse was how he tried to weasel out of the situation, claiming that it was all a big mistake. 

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