Thursday, October 20, 2005

All in the name of science? Part 2

During today's cross-examination, Eric Rothschild returned to our favorite subjects of bacterial flagellum and irreducible complexity. (This writer vastly prefers them to blood clotting cascades. But, I digress.)

Rothschild introduced an article written by James Curtsinger in the Minnesota Daily (and posted in response to an earlier blog entry).

While you're at PubMed [Curtsinger writes] try searching for "bacterial flagella secretion." One of the resulting papers, by SI Aizawa (2001), reports that some nasty bacteria possess a molecular pump, called a type III secretion system, or TTSS, that injects toxins across cell membranes.
Much to Dr. Behe's distress, the TTSS is a subset of the bacterial flagellum. That's right, a part of the supposedly irreducible bacterial "outboard motor" has a biological function!

"Did you agree to that?" asked Rothschild. "I don't recall," replied Behe, indicating that if TTSS is a subset, bacterial flagella are still irreducibly complex and must be the product of a designer. "When you see a purposeful arrangement of parts," said Behe, today, "it bespeaks to a designer."

Rothschild then brought up the gradual process of "slow design," a subject of Tuesday's testimony. This, Rothschild shared, "is what I experienced in my kitchen."

But, seriously folks...

Rothschild continued, "At some time, the bacteria would not have all of these parts. That is a phenomenon of both natural selection and ID, correct?"

Behe disagreed. "Until it has all of its parts, it's problematic to call it flagellum... No one has said how you could get from TTSS to flagellum. We see nothing that bears on the question of natural selection or random mutation...The crucial question is mechanism."

"In evolution, the mechanism suggested is natural selection." Rothschild responded, asking, "What is the mechanism suggested [by] slow design?" According to Behe, "we don't have a description of the mechanism [in evolutionary theory]. We do in intelligent design."

We do?

Rothschild: "The only way that we know that a designer exists is that objects that are designed exist?" Behe agreed. That seemed good enough for him.

Behe has written in Darwin's Black Box that there could be both multiple designers and/or competing designers. Rothschild asked today if there have been "any new irreducible complex systems [that have emerged] in the last five..." ten, fifty or 100 years.

Behe: "All studies considered are much older than that."
Rothschild: We "can't infer from that that the intelligent designer still exists."
"Correct," said Behe
Rothschild: "Is that what you want taught to high school students?"

But, we learned today, Behe has proposed a way to test the theory of irreducible complexity in his article 'Reply to my Critics,' published in the November 2001 issue of Biology and Philosophy.

In fact, intelligent design is open to direct experimental rebuttal... In Darwin's Black Box I claimed that the bacterial flagellum was irreducibly complex and so required deliberate intelligent design. The flip side of this claim is that the flagellum can't be produced by natural selection acting on random mutation, or any other unintelligent process. To falsify such a claim, a scientist could go into the laboratory, place a bacterial species lacking a flagellum under some selective pressure (for mobility, say), grow it for ten thousand generations, and see if a flagellum - or any equally complex system - was produced. If that happened, my claims would be neatly disproven.

Rothschild asked Behe if he could claim that his own theory is "well tested?"

"Yes you can... from the inductive argument. When you see a purposeful arrangement of parts we always see that as designed."

Yet, Behe proposes a test, which would in his estimation take about 2 years. Has he himself undertaken it? "I was advising people who are skeptical that this is the test...I think I'm persuaded by the evidence."

In fact, no intelligent design proponent has undertaken it. Presumably, this is because they are also persuaded by "inductive reasoning." But, here's the thing with their concept: it starts with a functioning organisms, say a bacterial flagellum and "works backwards by removing parts." If the precursor is not functional this demonstrates irreducible complexity. But, evolution doesn't work this way; it starts from the precursor and moves forward. Even Behe admitted - in 'Reply to My Critics' and in court - this is a "serious weakness," a "defect" in the theory. Any immediate plans to repair it? No.

And, yet, when we're talking evolution, say, of the immune system...

According to Behe "there is no detailed rigorous explanation [explaining that the immune system could] arise from random mutation or natural selection." So, Rothschild offered Behe 58 articles written over a 20-year period, a half dozen books and several chapters out of immunology texts all addressing this issue.

But, "not only would [Behe] need to see it mutation by mutation...[he] would also want to see relevant information such as population, selective value, detrimental effects..." He described these works as "analogous to the theory of aether...working within the aegis of a theory."

Like using the terms of the theory to prove the theory? That sounds familiar.

See, Behe studies peer review articles about cells and concludes that they "strongly look like a purposeful arrangement of parts, a hallmark of intelligent design." But, he "surveys the scientific literature and sees no evidence for a Darwinian explanation." Of course, "the hypothesis of design is tested differently than Darwinian evolution," claims Behe. Like... how scientists tested aether?

submitted by Amy Laura Cahn, Community Education Organizer, ACLU of PA


Anonymous Anonymous said...

This is turning into another monkey trial, with Rothschild making a monkey out of Behe. Retro evolution at work? Behe's embarrassing confusion over "mechanism" and whether ID is natural or supernatural are just two of the more obvious laughers. He is also terribly ambiguous about whether his partial acceptance of Darwinian evolution allows speciation (as in gorillas and chimps) and whether events happen on Biblical or geological time scales. These are extremely important points if you're going to present this to young high school students: his muddy views are often contrary to the party line expressed in "Pandas". If Behe can't explain what ID is in a consistent way, how does he expect 9th grade science teachers, much less their students, to have an intelligent discussion of its pros and cons vs. evolution? The only intelligent conclusion that I can see coming out of it is that ID is a bunch of hooey.
Once you strip away all of his circumlocutions, mis-directions, irrelevancies, and self-contradictions, his argument comes down to the tautological mantra: you can inductively conclude that an intelligent designer is at work if something appears to have been designed. Or maybe more accurately, *I* can inductively conclude...if something appears *to me* to have been designed. His "evidence" is in the eye of the beholder, and that ain't science, folks. If you are unsure about whether something shows "design", ask Behe.
Behe's GOTCHA, his proposed empirical test of ID — the one about letting bacteria grow for 2 years to see if they evolve flagella (or, maybe legs, wheels, or flippers) — is a complete red herring. Behe and his supporters won't go near actually doing this, or any real experiment, because they have to keep thngs at the metaphysical level. (I almost wrote, "any OTHER real experiment, but the one he proposes doesn't pass that test.)
One can with confidence make two predictions about the outcome of his suggested experiment if anyone were (to waste their time) to do it: the first is that flagella (or other such locomotion device) will not appear, and second, that the organisms WILL discover (but by straightforward mutation/selection) another way to improve their fitness in the imposed environment, for example, by up-regulating an existing enzyme system to allow them to grow faster. That's all that selection criteria can select for, not the creation of some Rube Goldberg that wouldn't solve their problem any better (which is just to beat out the local competition). The bugs are really more clever, in a manner of speaking, than the idea Behe proposes. I suspect he knows that.
A second problem with this hypothetical experiment is that conditions under which it could feasibly be carried out in the lab are completely artificial and irrelevant to those "in nature" where, presumably, evolution in the real world occurs. A pure bacterial culture growing in the lab in a medium arbitrarily defined by the experimenter is nice and neat, but hardly "natural". Bacteria, in the complex biological environment in which they naturally exist, are well-known to swap genetic material between species by several mechanisms, including via bacterial viruses. (Could be the designer saw to that?) Does anyone want to try this test in the equivalent of an outdoor privy? Another technical point is that it is well known that the time scale of evolutionary change occurs not simply by the number of "generations" but also by real (calendar) time. So, if we're going to give this a meaningful test, we ought to let it run for perhaps 200 million years. Behe foresees that objection, but he insists on insulating his ID hypothesis from any constraints of time scale (or mechanism, for that matter). Very convenient. That leaves its predictive power open-ended, which is to say, useless as a scientific concept. [In short, there are many ways for a complex "purposeful" device to have arisen during evolutionary time via acquisition of sufficiently useful bits and pieces than Behe is willing to consider.]
The third problem with his experiment, as proposed, is epistemological: what hypothesis, exactly, is being tested and, does the experimental design allow a definitive test of that hypothesis? You can put money on the outcome: no flagella. Does that negate evolution? No, because the controlled laboratory conditions are not relevant to how "macroevolution" occurs. Does it negate ID? No, the designer may have been on holiday. If the extremelely unlikely result were: Lo and behold, flagella!, would that cleanly support (or negate) either evolution or ID? Again, NO. Flagellar appearance would probably be a better argument FOR ID than for evolution, in my opinion, even though Behe seems to be of the opposite view. But what would then happen in this hypothetical situation is that others would try to repeat the experiment (the 2-year lab version, that is) to see if it is reproducible, and if it is, to go further to try to find out what in the sam hill is going on here.
Behe seems to claim that IC implies that it is IMPOSSIBLE for complex structures to arise by evolution, although he equivocates on that critical point as well. He contradicts himself when he says that future research may force us to change our position on how complex structures arise. Which is it? Or is he saying that future research will give us more specifics about ID, but that's not true of evolution? If he means what he says, he denies any feasible evolutionary reconstruction is possible (whether it's what actually happened is irrelevant to the principle). Such a feasible reconstruction has been provided in the case of blood clotting, for example, one that would satisfy most reasonable biologists because it completely consistent with current information about the mechanisms underlying evolution. So, Behe's response (of course) is to move the goalposts back and demand a mutation-by-mutation exposition. You can never lose that one. Creation science/ID/sudden appearance is safe. You can have faith in that.

11:01 AM  

Post a Comment

<< Home