Kenneth Miller, Michael Behe, and the Irreducible Complexity of the Blood Clotting Cascade Saga

Casey Luskin
January 1, 2010

In December of 2008, Casey Luskin posted on Evolution News & Views a 3-part series responding to the arguments of Professor Kenneth R. Miller against Michael Behe's arguments in Darwin's Black Box for irreducible complexity of the blood clotting cascade. 

To recap, Miller argued during the Dover trial and in his book Only a Theory that if the blood clotting cascade works without certain parts, then blood clotting isn’t irreducibly complex.  But those parts cited by Miller were parts that Behe expressly did not claim in Darwin’s Black Box are part of the irreducibly complex core of the blood clotting system.  Miller misrepresented Michael Behe’s arguments in Darwin's Black Box.

Roughly speaking, there are three “prongs” to the blood clotting cascade: two pathways which initiate the cascade (the extrinsic and intrinsic pathways) and then the cascade itself, which forms the clot. These prongs are illustrated in the diagram below:

Simply put, in Darwin’s Black Box, Michael Behe only argues for irreducible complexity for the components after the “fork” (red) in the blood clotting cascade.  Behe makes this unmistakeably clear, writing: “Leaving aside the system before the fork in the pathway, where some details are less well known, the blood-clotting system fits the definition of irreducible complexity.” (p. 86) 

Behe also made this clear in his Dover testimony that his arguments only applied to components after the fork:

"The relative importance of the two [initiation] pathways in living organisms is still rather murky. Many experiments on blood clotting are hard to do. And I go on to explain why they must be murky. And then I continue on the next slide. Because of that uncertainty, I said, let's, leaving aside the system before the fork in the pathway, where some details are less well-known, the blood clotting system fits the definition of irreducible complexity. And I noted that the components of the system beyond the fork in the pathway are fibrinogen, prothrombin, Stuart factor, and proaccelerin. So I was focusing on a particular part of the pathway, as I tried to make clear in Darwin's Black Box. If we could go to the next slide. Those components that I was focusing on are down here at the lower parts of the pathway. And I also circled here, for illustration, the extrinsic pathway. It turns out that the pathway can be activated by either one of two directions. And so I concentrated on the parts that were close to the common point after the fork. So if you could, I think, advance one slide. If you concentrate on those components, a number of those components are ones which have been experimentally knocked out such as fibrinogen, prothrombin, and tissue factor. And if we go to the next slide, I have red arrows pointing to those components. And you see that they all fall in the area of the blood clotting cascade that I was specifically restricting my arguments to. And if you knock out those components, in fact, the blood clotting cascade is broken. So my discussion of irreducible complexity was, I tried to be precise, and my argument, my argument is experimentally supported."

Ken Miller’s response to Behe was that certain vertebrates—such as the puffer fish or certain cetaceans—lack components of the intrinsic pathway (such as blood clotting factors XI, XII, and XIIa), but their blood still clots.  The problem with Miller's argument is that all of the components he cites come before the fork (from the blue "prong"). Since Behe made it clear in Darwin’s Black Box that his argument for irreducible complexity only applied to components after the fork (the red), Miller did not actually test or refute Behe's arguments. 

This was the essence of Luskin's response to Miller in December, 2008: Dr. Miller tested for irreducible complexity in components of the blood clotting cascade that Behe never argues are irreducibly complex in Darwin’s Black Box.

The Blood Clotting Saga Continues

Dr. Miller subsequently replied to Luskin by blogging at Discover Magazine, continuing to misrepresent and misquote Behe's arguments.  Then, Michael Behe and Casey Luskin responded to Miller's responses, pointing out that Miller had grossly misquoted and misrepresented Michael Behe's arguments. In fact, Miller's entire argument is predicated upon a misrepresentation of Behe's argument in Darwin's Black Box.

As of February 1, 2010, Miller has not responded to the rebuttals from Behe and Luskin. Instead, Miller has posted on his "Evolution Resources Page" a link to his own original responses to Luskin, boasting that they are "A response to charges from the Discovery Institute." But Miller has in fact not responded to the charges from Discovery Institute because he has not responded to counter-rebuttals from both Behe and Luskin showing Miller's blatant misquotes of Behe.

To help the reader sort through this complex series of arguments, the relevant articles in this saga are linked below so the reader can decide: Has Ken Miller really answered Michael Behe's arguments in Darwin's Black Box for the irreducible complexity of the blood clotting cascade?

Articles in the Blood Clotting Cascade Saga:

Luskin's Initial Salvo:

Ken Miller's Reply to Luskin:

Behe's Reply to Miller:

Luskin's Reply to Miller (and Discover Magazine):

Ken Miller's Reply to Behe and Luskin Showing that Miller in fact did not misrepresent Behe's arguments:

  • Reply does not exist.