Wednesday, December 07, 2005

The Tautology Objection

In yesterday's post I criticized this article, by Tom Bethell, from National Review Online. However, I left one of his arguments unanswered.

The argument is that natural selection is completely vacuous as a scientific principle. Bethell attempts to make this argument in two different ways. First he writes:

We have been trained to be blasé about the marvels of creation. “Oh, evolution did that,” we say. “It was just a matter of random mutation; nothing surprising there.” “These things arose by accident and were selected for.”

That phrase — “it was selected for” — is regarded as a sufficient explanation for . . . everything. The same mundane phrase is given as the explanation for everything under the sun. How did the bats get sonar? “It arose by an accidental mutation of the genes and was selected for. Next question?” How did the eye develop? “Piecemeal. There was a random mutation and it conferred an advantage so it was selected for. Then the same thing happened over and over again. Next question?” How did the camel get its hump? “Random mutations conferred some advantage and so they were selected for. Next question?”

This is the science before which all knees must bend? These explanations are no better than “Just-So stories” (as one or two Harvard professors have rightly said). No actual digging in the dirt is needed: The theorist merely contemplates the trait in question and makes up a plausible story as to how it might have been advantageous.

If I write about this subject for a hundred years I will never understand what could make a person that arrogant. Both the professional and popular level literature on evolution is chock-full of detailed analyses for how specific adaptations evolved gradually via selection. Biologists base these scenarios on in-depth studies of data from paleontology, genetics, anatomy, and embryology. But Bethell simply ignores it all, preferring instead to promote vicious stereotypes of his intellectual betters.

For example, when paleontologists dig up a detailed series of fossils showing how reptilian jaw bones evolved into mammalian ear bones, and when the scenario suggested by the fossils is subsequently backed up with evidence from embryology and anatomy, are scientists really out of line in saying the mammalian inner ear evolved gradually? (See Stephen Jay Gould's essay “An Earful of Jaw” from his anthology Eight Little Piggies for a good explanation for this.)

Or when we find that the numerous proteins involved in human blood clotting have just the form they ought to have if they formed via a series of gene duplication events starting from a common pancreatic enzyme, when we observe that invertebrates such as lobsters make do with a blood clotting system bearing a striking resemblance to the final stages of our own, and when the scenario of blood clotting evolution suggested by these observations is then used to make further predictions about critters not yet studied (predictions subsequently born out by further research), is it the scientists who are being unreasonable in calling the problem solved, or the creationists for demanding more evidence? (See Ken Miller's excellent description of blood clotting evolution for more details).

The fact is that examples like this could be multiplied endlessly. Bethell either lacks the knowledge or the integrity to comment seriously on this subject.

But Bethell has another argument up his sleeve:

George Will has made one accurate criticism of the idea he so dislikes: “The problem with intelligent design is not that it is false but that it is not falsifiable. Not being susceptible to contradicting evidence, it is not a testable hypothesis.” This is true; but he should have added that Darwin's theory of evolution by natural selection is not falsifiable either. Darwin's claim to fame was his discovery of a mechanism of evolution; he accepted “survival of the fittest” as a good summary of his natural-selection theory. But which ones are the fittest? The ones that survive. There is no criterion of fitness that is independent of survival. Whatever happens, it is the “fittest” that survive — by definition. This, just like intelligent design, is not a testable hypothesis. As the eminent philosopher of science Karl Popper said, after discussing this problem that natural selection cannot escape: “There is hardly any possibility of testing a theory as feeble as this.” Popper was the first to propose falsification as the line of demarcation between theories that are scientific and those that are not; both intelligent design and natural selection fall by this standard. (Emphasis Added)

And there it is. The tautology objection. It has been a mainstay of anti-evolution writing for decades. Bethell himself devoted an entire article in Harper's Magazine to it in 1976. David Berlinski used it in his manifesto “The Deniable Darwin.&rdquo. And Phillip Johnson used it in Darwin on Trial.

Curiously, Answers in Genesis includes this argument among those that creationists shouldn't use, which is one more piece of evidence that young-Earth creationists actually have more integrity than their cousins in ID. (But then again, twice nothing is still nothing).

Apparently Bethell does not aspire to the high standards of AiG. Even before getting to the substance of the argument, such as it is, we should pause to note something very odd. Stephen Jay Gould said it well in his refutation of Bethell's 1976 article:

Bethell's argument has a curious ring for most practicing scientists. We are always ready to watch a theory fall under the impact of new data, but we do not expect a great and influential theory to collapse from a logical error in its formulation.

Indeed. I often tell people that in many cases you can sniff out a bad scientific argument even if you know little of the actual science. Any argument that requires you to believe that several generations of scientists have overlooked a simple logical fallacy can be dismissed out of hand.

Another curious feature of this argument is that it is not clear what, exactly, it is meant to prove. The phrase “survival of the fittest” is catchy and captures the essence of how natural selection works, but it is not something that comes up much among biologists. Contrary to Bethell's preposterous caricature, no scientist has ever moved on the next question after asserting that a particular structure evolved gradually.

I suppose the idea is to show that natural selection is vacuous, and therefore can't be used to explain anything. But this argument shows no understanding of how selectionist reasoning is actually used in routine scientific work. When you have finished playing whatever word games amuse you, it will still be true that there is nothing tautological about saying, for example, that industrial pollution made it advantageous for certain moths to have a dark, rather then light coloration. Selectionist thinking is used to generate testable hypotheses about actual organisms.

The most direct way of refuting Bethell's argument is simply to point out that the bold-faced statement above, upon which Bethell's entire argument rests, is actually quite false. There are criteria of fitness independent of survival. This is the approach Gould took, and he made the obvious point:

My defense of Darwin is neither startling, novel, nor profound. I merely assert that Darwin was justified in analogizing natural selection with animal breeding. In artificial selection, a breeder's desire represents a “change of environment” for a population. In this new environment, certain traits are superior a priori; (they surive and spread by our breeder's choice, but this is a result of their fitness, not a definition of it). In nature, Darwinian evolution is also a response to changing environments. Now, the key point: certain morphological, physiological and behvioral traits should be superior a priori as designs for living in new environments. These traits confer fitness by an engineer's criterion of good design, not by the empirical fact of their survival and spread. It got colder before the wooly mammoth evolved its shaggy coat.

Not a difficult point, but one that Bethell has apparently failed to grasp.

Actually, there is one more angle to this worth discussing, but we sill save that for the next post. Stay tuned!


At 7:02 PM, Anonymous John B said...

Oh no! Not the tautology objection!

We discussed that one back in my evolutionary mechanisms course in 1988, and it was old even then. Those guys really need some new material, what's next, complaining about the lack of dust on the moon?

Nicely refuted, btw. Outstanding website.

At 7:20 PM, Blogger Jason said...

john b-

The classics never go out of style.

Thanks for the kind words about the post and the blog.

At 4:32 AM, Anonymous Richard Wein said...

The concept which the phrase "survival of the fittest" is intended to convey is this: some individuals inherit a greater propensity to survive (and reproduce) than others, and this state of affairs gives rise to adaptive evolution. Whether "survival of the fittest" is a good phrase for conveying that concept is open to question, but the concept itself is clearly not tautologous.

At 9:36 AM, Anonymous Anonymous said...

I love the AIG list - "Don't use these arguments. They're stupid. Use these stupid arguments instead."

At 11:53 AM, Anonymous Anonymous said...

Jason wrote I often tell people that in many cases you can sniff out a bad scientific argument even if you know little of the actual science. Any argument that requires you to believe that several generations of scientists have overlooked a simple logical fallacy can be dismissed out of hand.

But a substantial number of people are willing to believe just that. And that belief then requires an explanation: Why do scientists ignore the (alleged) logical fallacy? Why, it's obviously because the edifice of Darwinism is necessary to justify scientists' preferred atheistic metaphysics. They impute to scientists the same motivation that they have: use anything they can get their hands on, however fallacious it might be, to buttress an a priori metaphysical commitment.


At 4:32 PM, Blogger John Farrell said...

Jason, excellent article. I've been reading Bethell for years, and his idiocy regarding relativity is what got me started on what eventually became this article for Salon.

A remarkably lazy journalist, his M.O. is basically to find one or two fringe scientists to buttress his pre-conceived notions about a theory and the hone their quotes to proclaim the coming downfall of (fill in the blank).

At 4:26 PM, Blogger Jason said...

John Farrell-

Thanks for the kind words about the blog entry, and thanks also for the link to your article. I will do a separate blog entry about it next week. (I'm a little backed up with blog fodder at the moment, but I promise to get to it shortly).

Bethell, like David Berlinski, strikes me as someone who is largely opportunistic. He is perfectly happy to parrot whatever his editors want to hear.

At 8:29 PM, Blogger John Farrell said...

Thanks, Jason. I think you're absolutely right about opportunism factor, but I remain mystified about Berlinski. He is a good writer and I really enjoyed his Tour of the Calculus when it first came out. But his pieces for Commentary about evolution just left me scratching my head....

At 5:28 PM, Blogger Jason said...

john farrell-

We have a lot in common. I also liked A Tour of the Calculus, though I did not care for his logic book (The Advent of the Algorithm). I even read one of his mystey novels (readable, but I can't say I had any urge to read another). I haven' read any of his more recent books, mostly because I'm so disgusted with his Commentary pieces.

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At 5:01 AM, Blogger MANHHIEU said...

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I love the AIG list - "Don't use these arguments. They're stupid. Use these stupid arguments instead."


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