TBS: Next, we would like to press you a bit on your conception of ID. First, let’s agree to some terminological conventions, which will allow us to pose our questions more precisely. Let us call the claim that present-day life forms have descended from ancient life forms the “common-descent hypothesis,” and the claim that the neo-Darwinian theory of natural selection adequately explains common descent, the “selection-mechanism thesis.” Our first question, then, is this: What degree of epistemic warrant would you ascribe to the common-descent hypothesis? What degree to the selection-mechanism thesis? What are the main biological observations of complexity that the selection-mechanism thesis is simply unable to answer or explain?
WD: Common descent seems to me not all that well established. Certain fossil and molecular evidence suggests that a fair amount of evolution may have taken place (perhaps to the level of families, orders, or even classes), but the grand picture of evolution (“monad to Man,” as Michael Ruse calls it) seems to me unsupported. Indeed, the evidence seems to be against it. Illustra Media recently did an interesting video titled Darwin’s Dilemma, focusing on the Cambrian explosion, which challenged Darwin’s theory back in his day and continues to do so today. Jonathan Wells and I devote a chapter to this in our book, The Design of Life.
My skepticism about common descent is not universally shared in the ID community. Michael Behe, for instance, holds to the common-descent hypothesis. But that has not resulted in any rift between him and me. We are both convinced that the selection-mechanism thesis fails. For the sake of argument, I’ll often allow that common descent may be true, even though I personally reject it. But the ID community is convinced that the selection-mechanism thesis is not just unwarranted, but ascertainably false.
For the sake of argument, I’ll often allow that common descent may be true, even though I personally reject it. But the ID community is convinced that the selection-mechanism thesis is not just unwarranted, but ascertainably false.
In saying this, we are not denying that natural selection operates. Indeed, it does. But we are denying that its range and power are anything like what the Darwinists claim. And the evidence, we would contend, is all on our side. This is probably not the place to rehearse such arguments. I refer readers to The Design of Life. I would also refer readers to an article I coauthored with Bob Marks entitled “Life’s Conservation Law: Why Darwinian Evolution Cannot Create Biological Information.” This paper can be found in Nature of Nature: Examining the Role of Naturalism in Science anthology, cited earlier.
As for the types of systems that the selection-mechanism thesis is unable to account for, I would point to the irreducibly complex systems to which Michael Behe first drew our attention, but with a twist. Many of the systems that Michael Behe examined in Darwin’s Black Box (Free Press, 1996) are dispensable to life in the sense that organisms can be alive without them. Nonetheless, some systems, such as the protein synthesis apparatus, are not just irreducibly complex, but also indispensable to life.
Some systems, such as the protein synthesis apparatus, are not just irreducibly complex, but also indispensable to life.
This strengthens Behe’s argument for the unevolvability of these systems, because simplifying them does not merely render unrecoverable their function, but also precludes life as such—and if you’re not alive, you can’t be evolving. The loophole that Behe’s critics have always cited against him is that irreducibly complex systems might evolve from simpler systems with different structures and functions. Thus, the function of the irreducibly complex system in question would have to be acquired later in the game. But if the function is indispensable, this loophole is closed.
Think of the bacterial flagellum. It is irreducibly complex, yes, but it is also dispensable in the sense that bacteria can get by without this motility device. But protein synthesis, which is irreducibly complex, is also indispensable. Evolve into it from something that can’t perform protein synthesis, and you’re dead.
TBS: One way of looking at ID, overall, is as a pairing of two very different kinds of claims. On the one hand, there is the negative claim that the selection-mechanism thesis is false—that the theory of natural selection is wholly inadequate as an explanation of the fantastically complex structure and function of living things. The reason is that the proposed selection mechanism simply lacks the conceptual resources to “save the phenomena.” On the other hand, ID, as usually construed, makes a positive claim, which is an inference from the appearance of design in living systems—together with the impotence of the selection mechanism to explain it—to the conclusion that design has actually been imposed on living matter by an external agent (call this the “external-design thesis”).
Next: But it seems to us that these two claims have very different degrees of warrant
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