Science & Faith
12/7/13 at 11:46 AM 16 Comments

UC Berkeley's Marshall Debates Meyer on Darwin's Doubt: Respectful Discussion of Intelligent Design

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On November 30, 2013, two scholars demonstrated how to respectfully debate the merits of intelligent design in the natural sciences. Regardless of who you think "won" this remarkably friendly debate, perhaps we can all agree that Stephen Meyer and Charles Marshall model well how to engage in civil discourse over one of the most polarizing discussions in science today. Philosopher of science Stephen Meyer debated UC Berkeley paleontologist Charles Marshall on the Cambrian explosion and its treatment in Meyer's book Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design. Hosted and moderated by Justin Brierley of Britain's Premier Christian Radio, this exchange is a milestone of civility in debate about science and its philosophical underpinnings. Listen to it yourself (on a Mac, control-click the link to download the MP3).

Before you begin listening, examine this Listener's Guide to the Meyer-Marshall Radio Debate (and follow its weblinks) to get oriented. Here are some highlights from this Guide to which you should pay special attention in order to get the most of your listening experience.

Recall that in Darwin's Doubt Meyer argues that intelligent design provides the best explanation for the origin of the genetic and epigenetic information necessary to build the novel forms of animal life that arise in the Cambrian period. In support of that argument, Meyer offered five separate critiques of the ability of the mutation/selection mechanism to generate that necessary information. He also later critiqued six post neo-Darwinian evolutionary mechanisms and made a positive argument for intelligent design by showing that intelligent agents alone have the power to produce large amounts of functionally specified digital information.

In this regard, note that Marshall says Meyer's book is limited by a 1980s genetic perspective. Meyer corrects Marshall on this matter, pointing to the book as described above, and Marshall never comes back to support his initial charge of Meyer's alleged lack of current scientific perspective].

Listen also for the back and forth in the radio debate about the following:

In his review of Darwin's Doubt in Science, Marshall attempted to rebut [Meyer's argument for the intelligent causation of the new biological information needed to build Cambrian animals], not by demonstrating that any known evolutionary mechanism can produce the information necessary to build the Cambrian animals, but instead by contesting the idea that a significant amount of new genetic information would have been necessary to build these animals. In particular, Marshall claimed that the evolutionary process could have "rewired" the gene regulatory networks that control how other "already existing genes" are expressed during the process of animal development.

During the radio debate,

Marshall amplified this argument by claiming that Meyer's argument presupposed an outdated "1980s model of the way genes operate" and that his book "confronted a different set of problems that hark back to an older age." According to Marshall, biologists no longer believe that building the diverse forms of Cambrian animals would require evolving new genes (or, at least, many new genes). Instead, Marshall argued, again, that new body plans could be generated by rewiring networks of already-existing genes, especially those which are part of the developmental gene regulatory networks (dGRNs) that control the timing and expression of pre-existing genes during animal development. Marshall pointed out that animals have far fewer genes than we once expected, and that today it is thought that "animals use essentially the same genes, just deployed slightly differently." By changing the deployment of those genes -- by rewiring their dGRNs -- Marshall thinks new body plans can arise.

Meyer had a ready response. After pointing out that he did not presuppose a 1980s gene-centric understanding of animal development, but that he had examined and discussed in Darwin's Doubt the hypothesis that dGRNs played a major role in the evolution of animals, Meyer noted that Marshall's proposal does not eliminate the need to explain the origin of genetic information. Specifically, he showed that Marshall's proposal presupposed, but did not explain, several separate sources of pre-existing genetic information.

In the first place, Meyer cited some of Marshall's own scientific papers to show that Marshall himself acknowledged the need for what Marshall called "gene novelties" -- new genes -- for building the specific anatomical structures (and parts) that characterize the Cambrian animals. (Meyer pointed out that building these animals would have required many so-called "taxon specific" genes that are known to be completely unique to specific animal forms.)

Second, Meyer also noted that the developmental gene regulatory networks that Marshall emphasized were themselves made of genes and gene products and that Marshall had presupposed the existence, but not explained the origin, of these regulatory genes.

Thirdly, Meyer pointed out that Marshall's proposal assumed a Precambrian pre-adapted genome with many of the regulatory genes for building Cambrian animals. Meyer noted that this proposal also does not eliminate the need to account for the origin of the genetic information necessary to produce the Cambrian animals. Rather, it just pushes the problem of the origin of some of that information back into the Precambrian.

Fourthly, Meyer noted that Marshall's proposed "rewiring" of gene regulatory networks itself requires an infusion of new information. In particular, it would have required a whole host of coordinated genetic mutations (to various regulatory regions in the genome), requiring significant informational inputs. (This need to generate multiple coordinated mutations would have faced many of the problems faced by evolutionary mechanisms which Meyer discusses in Chapter 12 of Darwin's Doubt.)

Thus, overall, Meyer showed that Marshall's proposal presupposed, but does not explain, the origin of several key sources of genetic information (and, I would add, that it does nothing to explain the origin of the epigenetic information that Meyer discusses in Chapter 14 of Darwin's Doubt).

Having read this summary of Meyer's points, listen carefully for how Meyer explain this in the radio debated, and how Marshall reacts:

In response, Marshall argued that Meyer had been forced to shift ground by allowing that the biological information could have arisen in the Precambrian, rather than the Cambrian. Meyer readily acknowledged that information necessary to build the Cambrian animals might have arisen in the Precambrian period, but that did not solve the central problem posed by Darwin's Doubt -- which is the problem of the origin of that information, not precisely when it originated. Meyer noted several times that Marshall had simply pushed the problem of the origin of the necessary information back into the Precambrian, without offering any explanation for how that information had arisen.

Meyer also pointed out that experiments on developmental gene regulatory networks in actual animals have repeatedly shown that perturbing the central components of these networks have catastrophic consequences for animal development. Meyer noted that there is no empirical support for the idea that dGRNs could have been labile in the past. Meyer made this same point in his response to Marshall review. In support of this claim, Meyer cited the work of Eric Davidson, whom Marshall had earlier accused Meyer of neglecting in his discussion of how body plans are built.

In fact, Meyer discussed the importance of Davidson's work extensively in Chapter 13 of Darwin's Doubt, which makes it odd that Marshall charged during the debate that Meyer "completely missed" this literature. As Meyer wrote ...

At this point you would do best to listen to the radio debate itself. Then go here to read the rest of this Listener's Guide, starting with the block quote from Meyer's book located about halfway into the Guide. Keep in mind that Marshall is one of the world's leading Cambrian paleontologists and evolutionary biologists. When you hear him interact with Meyer, you may draw the conclusion offered in the Guide that a materialistic evolutionary theory of the origin of the major kinds of life "has little left to offer with respect to that critical question" of the origin of the biological information necessary to build Cambrian animals. Luskin, the author of the Guide concludes:

After listening to the debate, I was impressed with Charles Marshall the evolutionary biologist, the scientist, and the thinker, but was also left thinking that if his arguments about the origin of biological information were the best that mainstream evolutionary biology has to offer, then the future of biology definitely belongs to ID.

Also note that elsewhere in the blogosphere, Jerry Coyne, author of Why Evolution Is True wrote this about Marshall's radio debate with Meyer:

I wish more paleobiologists would have a look at Meyer's book. Not that he'll listen to their critiques, for he and his Discovery Institute cronies aren't interested in scientific argument, and always find a way to discredit the several negative reviews. And although it's annoying to take time out of one's science to debunk ID, having a paper record against its arguments is valuable.

ENV's David Klinghoffer offered an appropriate response to Coyne's complaint:

Coyne never ceases to amaze. We won't listen to critiques? If you follow us at ENV you'll know that we seek out every opportunity to listen and reply in detail to genuine criticism (as opposed to mere name-calling). It's our opponents who then present those critiques as not only unanswerable but unanswered.

We aren't interested in "scientific argument"? But Meyer's whole book is a scientific argument at a high level, and we've conducted a very extensive argument with critics, those that dare to answer back. It's Coyne who has dodged or ignored every single challenge to debate or argue with us.

Coyne is typical of the most vocal critics of intelligent design. Marshall's review of Meyer (in the journal Science and in the Premier radio debate) is a refreshing break from such Coynian tactics. I hope that the intellectual virtues on display in Marshall's respectful interactions with Meyer will encourage other ID critics to emulate the civility of the Marshall-Meyer exchange. This is publicly accessible scientific discourse at its best.

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