Sunday, April 27, 2008


Up and Away

The St. Louis Post-Dispatch has an uncommonly astute editorial today. The editorial notes the report of a:

... remarkable new genetic study published last week has demonstrated that the closest living relative of the giant T. rex are birds — specifically, chickens and ostriches — rather than reptiles like alligators and lizards.
It then points out the incongruity of the Missouri legislature's attempt to pass an (anything but) "academic freedom" law, aided and abetted by Ben Stein and his traveling burlesque (of science) show, Expelled:

The war is being waged in legislatures and movie theaters because it cannot be waged in the pages of scientific journals. Adherents of so-called intelligent design criticize what they call gaps in the evolutionary record, but offer no scientific alternative to explain the evidence. Indeed, they have tried to redefine the very nature of science to accommodate their preferred conclusion.

In the real world of science, theories gain credence by their power to both explain the past and predict the future. In the case of evolution, that future includes new evidence yet to be uncovered and novel ways of analyzing evidence discovered in the past.

Biologists long ago theorized the link between dinosaurs and birds. Their idea was based not just on the similarity of their bones, but also on fossilized remains of a so-called flying dinosaur in China — an animal with primitive feathers that could glide for short distances.

Now that science has given us the ability to perform genetic analysis, the evidence for that link is even stronger. Far from undermining the theory of evolution, the results of this new study strengthen it.
That is, indeed, the difference between science and ID. Science starts with a hypothesis that can be decided by empiric evidence and tests it over and over again and changes the hypothesis if incompatible evidence comes along. Only after a hypothesis gains a lot of evidence and survives all tests does it become a "scientific theory."

ID started from a hypothesis that God exists and never tests that core claim -- for the simple reason that science can't test it -- and instead makes the unjustified philosophical claim that anything we can't explain by our present understanding of natural causes must be the work of unnatural forces.

In this instance, ID doesn't even qualify as being for the birds.

I'm suspicious of ID, both of the claims and the motives for making them. But there's a problem here which is worth taking the time to address.

It seems to me that any ID proponent who's smarter than a pile of wood could very easily say:

"It's a reasonable inference, from the anatomical similarities of theropods and birds, that there would be genetic similarities as well. But that tells us nothing about the mechanisms which produced those similarities. You want us to believe that random variation and directional selection are individually necessary and jointly sufficient for explaining how such similarities are produced. But there is no demonstration that those well-documented mechanisms are capable of producing large-scale morphological changes. In any event, the fact of correlation between anatomical and genetic similarities does not bring us one step closer to such a demonstration."

On the one hand, against this objection, it seems to me that evolutionary theorists have no other choice but to say, "ok, so what else you got?" -- at which point the self-respecting ID theorist must be silent, since ID does not propose an alternative mechanism.

On the other hand, however, it strikes me that skepticism about evolutionary processes is irrefutable. That is: the evolutionary scientist can always prevail against the creationist or the design theorist when it comes to putting a coherent theory on the table for evaluation. And yet there is always, and perhaps necessarily always, room for skeptical doubt as to whether the proposed mechanisms are sufficient to account for the observed correlations.

The lesson I'd like us to draw here is that those of us who love and respect the practice of good science should not pretend to have refuted the skeptics, whether it comes to evolution or anything else. Skepticism about evolution, like skepticism in general, is irrefutable. Instead, we should keep to the level of "well, what else you got?"

I fear that in our own rhetorical excesses against pseudo-science, this distinction has been effaced.
... skepticism about evolutionary processes is irrefutable ...

Within science or outside of science? Within science, skepticism is welcomed but, once a reasonable mechanism for the existence of a phenomenon (and variation / mutation / gene duplication / etc. coupled with selection / drift / etc. are at least that) has been demonstrated, just saying "I don't believe it," while perhaps a reasonable philosophical / theological position, is not a reasonable scientific position.

It's not so much that ID can't offer a substitute theory for the current state of life (though it can't), it's that it can't produce a coherent hypothesis as to why we should think mutation / selection isn't sufficient to explain the current state of life.

The best ID has offered is irreducible complexity, which is purely a conceptual, instead of an empiric, objection. The only response necessary is a demonstration of conceptual routes to evolving IC structures. Scientists have succeeded in giving those.

In the absence of a hypothesis as to why we shouldn't accept current theory and the abence of any testable alternative to current theory, ID is scientifically empty and, therefore, within the scientific process, is worse than refuted. It's not even wrong.
"Skepticism about evolution, like skepticism in general, is irrefutable."

I think you're conflating skepticism in the generic sense with skepticism as scientists tend to use the term. Skepticism as a principle yields to evidence. Reflexive denialism does not. The latter is what is displayed by creationists when saying this:

"It's a reasonable inference, from the anatomical similarities of theropods and birds, that there would be genetic similarities as well. But that tells us nothing about the mechanisms which produced those similarities."

As Karl Popper adeptly pointed out, you can always rescue an idea if you constantly resort to ad hoc hypotheses to explain away instances of empirical failure. A good scientific theory is ideally one that is highly risky and, despite those high risks, survives stringent tests. Being irrefutable is, in fact, that fatal flaw of this retort, not to mention the majority of ID as a whole.
One should also consider that a genome is not the well-designed, efficient blueprint that some folks suggest. Compare placental and marsupial examples of ecologically equivalent species--they may physically resemble each other more than they resemble other members of their groups, yet genetically, are they closer to each other or to the members of their group? There's more than one way to build a thumb.
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