Why 'Darwin Strikes Back' fails
By JASON ROSENHOUSE, Special to the Times
Published October 21, 2007
Jason Rosenhouse is an assistant professor of mathematics at James Madison University. Rosenhouse reviewed Darwin Strikes Back by Tom Woodward for the National Center for Science Education, a proevolution group.
In Darwin Strikes Back, Tom Woodward sets himself up as a sort of arbiter between the evolution side and the intelligent design side. Starting in the early to mid 1990s, the ID folks started putting out a string of books and essays making their arguments. Scientists subsequently responded, ID folks responded to the responses and so on. Woodward's intention is to argue that scientists have responded with heat and venom to the ID folks, but that they have not effectively refuted the ID claims.
I find the following general types of difficulties in his book:
- He presents an inaccurate and caricatured version of the arguments made by the evolution side.
- He frequently does not reference the most scholarly refutations of the ID arguments, but often focuses instead on short book reviews in magazines where there is insufficient space to make an argument in depth.
- When he discusses the minutiae of the actual scientific issues, he routinely gets very important things wrong.
Here are some specific examples of what I am talking about.
Chapter Five of Darwin Strikes Back discusses ID proponent Michael Behe's notion of "irreducible complexity." Behe's idea was that if you look at certain complex biochemical systems, you find that they can be thought of as machines composed of several parts. He pointed out that in many cases, if you remove any one part out of the system, then the machine ceases to function.
As he tells it, this is a grave problem for evolution. Darwinists explain such complex systems by saying that they evolved gradually over a long period of time. You don't go from having no eyes in one generation to having fully formed eyes in the next generation. Each step in the process is obtainable from the previous one by a small, chance genetic variation. Natural selection then steps into assure that the initial stages of the organ are preserved over time. Thus, the interactions of chance (random genetic variations) and law (natural selection) can, given enough time, craft even very complex systems.
But if the system does not function unless all of its parts are in place, then it would seem that it could not have evolved gradually. Natural selection can't look to the future and say it is going to maintain a half-formed system simply because it will eventually become something good. It needs functionality in the present, which an "irreducibly complex" system can not have.
Thus, according to Behe, evolution requires a series of functional intermediates bridging the gap between no eyes and eyes -- but the reality of irreducible complexity makes such a series impossible. Note that this is an "in principle" argument. According to Behe, if you find irreducible complexity, then you can dismiss out of hand any thought that the machine evolved gradually.
Scientists offered two main kinds of arguments in reply. First, they pointed out that Behe's logic was simply wrong. That every part is needed in the present does not imply that the system could not have formed gradually in the past. You can see the basic principle in everyday life. Desktop computers are absolutely indispensable to everyday life today. But in the '70s and early '80s they were a luxury. Their indispensability evolved gradually over time. Likewise in biology. You could have a situation where some part that was not essential when it first appeared later became essential after further evolutionary changes.
Another example is a suspension bridge. While it is being constructed, a bridge can not support itself. It got built because there was a scaffolding supporting its weight. After the construction is completed, the scaffolding gets removed. Thus, looking at a system in the present tells you nothing about possible support structures that existed in the past.
There are biological analogues of both of these processes. So the first line of response to Behe was to point out that there are a variety of well-known, observable biological mechanisms through which a supposedly irreducibly complex system could nonetheless have evolved gradually. Since Behe was the one making grand claims about what was possible and what was not, it was for him to explain why these scenarios, which were, after all, drawn from actual scientific research, were not practical.
The second line of response was to point to specific biochemical systems, some of Behe's favorite examples among them, and point to actual professional research explaining how they evolved. There is a huge literature on the subject of blood clotting evolution, or immune system evolution, or eye evolution, to pick a few famous examples. The scientists who specialize in the study of these systems, the people who really know what they are talking about, do not see evidence of intelligent design in the systems they are studying. They see clear evidence of evolution. So it is not just that Darwinism can, in principle, explain complex systems (though that alone would be enough to refute Behe's argument), it is that Darwinism has done so repeatedly in practice.
In discussing the response to Behe's argument, Woodward lists three different approaches scientists have taken towards Behe's argument. First, he chides scientists for attacking an analogy Behe has used in describing irreducible complexity. Behe has used a mousetrap as an illustration of irreducible complexity, and scientists have pointed out that this is a bad analogy. Scientists have pointed this out, and rightly so, but this is hardly the main criticism of Behe's work.
Second, he says that scientists have resorted to the "unexplained does not mean unexplainable" defense. That is, Woodward is saying that scientists effectively agree that the systems to which Behe points are not currently explained, but that this is no reason to give up on the problem. Now, scientists do make this point. There are certainly many complex systems that have not yet been explained, simply because there are more complex systems in nature than there are biologists to study them. But this is not one of the major lines of response to Behe's arguments.
Thus, Woodward devotes the first 6-1/2 pages of his discussion to points that are not central to the case against Behe, and which are rhetorically weaker than the main arguments against Behe. In so doing he effectively creates a straw man, making it appear that scientists have focused on ancillary issues, rather than on the main thrust of Behe's argument.
It is only in his third part that Woodward mentions some of the main arguments raised by scientists against Behe, and here I'm afraid he does a thoroughly inept job of it. He gives no clear explanation of the arguments scientists are making. Worse, he bases his writing entirely on popular-level treatments of these subjects. That is, he does not reference the professional literature on these subjects, but relies instead on short essays published in venues intended to be readable by nonscientists, and even here he gives a badly distorted view of what is being argued. That simply will not do. If you are going to run around the country telling people that scientists have no idea how complex systems evolve, you really ought to do your homework first. Reading a few book reviews or a handful of exchanges on the Internet is not going to cut it.
Woodward also devotes a chapter to a book by Jonathan Wells titled Icons of Evolution, in which Wells attempted to show that many of the standard textbook examples used in discussions of evolution were false or misleading in important ways. Wells chose 10 examples. Scientists responded in the most direct way imaginable. They showed at length that in every case it was Wells' version of things that was wildly inaccurate, and that any charges of fraud were far more plausibly leveled at him than at scientists. I would refer you to an especially thorough, scholarly refutation of Wells' points, written by paleontologist Alan Gishlick, available here: www.ncseweb.org/icons.
But Woodward does not reference this discussion, widely known to people interested in this subject as one of the most thorough debunkings around. Instead he relies almost entirely on short book reviews that appeared in popular-level venues.
So once again he gives a false impression of what scientists have been saying. He makes it appear that scientists have responded with anger and vitriol without really addressing Wells' arguments. That is not true.
And when Woodward does discuss the actual science, he usually gets it wrong in very serious ways. For example, on Pages 103-104 of his book, Woodward discusses the Cambrian explosion. The Cambrian refers to one of the most ancient levels of rocks known on planet Earth. These rocks contain fossils of the earliest living creatures to inhabit the Earth.
As Woodward tells the story, the critters we find there show phylum-level differences. A phylum is one of the highest levels in the taxonomic hierarchy. When biologists categorize animals, they begin at the species level, grouping together animals capable of interbreeding. Closely related species are grouped into a genus. Closely related genera are grouped into classes and so on. The upshot is that if two animals are placed in different phyla, then they have wildly different morphological features. Humans, oysters and spiders are all in different phyla.
In stressing these phylum-level differences, Woodward wants to convey the impression that the animals found in the Cambrian fossils were as wildly different from each other as, say, humans and spiders are today. If this were true, it would be a serious problem for evolutionists. According to Darwinism, animals with wildly different physical attributes arise as the result of a long period of evolution. If huge differences are appearing at the earliest stages of evolution, then this would be very difficult to explain via the conventional theory.
Happily for evolution, Woodward has simply garbled a fairly basic point of taxonomy. Phyla are classifications used for modern organisms. Today, if you say two modern animals are in different phyla, then you are saying they are wildly different anatomically. But that does not mean that ancient organisms placed in the same phyla show the same level of difference.
When paleontologists place Cambrian fossil X in one phylum and Cambrian fossil Y in a different phylum, they are not saying that X and Y are as different from one another as humans and spiders. They are saying simply that X shows some feature that in modern organisms is associated with one phylum while Y shows some feature that is today associated with a different phylum.
The simple fact is that the Cambrian fossils do not show such wildly different anatomical features. Moreover, and contrary to what Woodward says, there are actually a fair number of Precambrian fossils that are clearly intermediate between the Cambrian life forms and more primitive creatures. Add to that the fact that this so called "explosion" took place over a period of some 50-million years, and you quickly see how empty Woodward's argument really is. The Cambrian explosion is a problem for evolutionists only in the sense that there are many possible explanations for it, but too little data for coming to a firm conclusion. This is not surprising, since we are trying to reconstruct something that happened around 600-million years ago. But the question is not whether we can give a definitive account of what happened during the explosion. The question is whether anything we have discovered to date seems to require the intervention of an intelligent designer.
The answer to that question is no.
I have barely scratched the surface of all that is wrong with Woodward's book. It is safe to say that you could open his book to almost any page and find gross scientific errors.
There is a reason people like Woodward do not spend much time making their case in front of scientists, preferring instead to speak to school boards and lay audiences. It is because scientists have the expertise to see through his fallacious arguments. Tell a room full of biochemists that no one has the faintest idea how complex biochemical systems evolve, and they will simply laugh. Lecture a group of paleontologists about how the Cambrian fossils show enormous, phylum-level differences, and they will know immediately that you have never studied their subject in any serious way.
On and on it goes. Woodward makes much of the fact that scientists frequently use strong rhetoric in describing the arguments of ID folks. Of course they do. ID folks run around the country effectively accusing scientists of the crassest sort of ignorance and incompetence. ID literature asserts that the common wisdom in every branch of the life sciences, whether in genetics, evolution, paleontology, anatomy, biochemistry and so on, is simply wrong. People study for years to become experts in any one of these disciplines, and then they have to put up with people with an obvious religious or political agenda completely distorting everything about their subject. Are you surprised that they respond with a bit of anger?
There is a simple fact that must be explained here. Every biology department in the country either has a department devoted to evolutionary studies, or has a significant division within its biology department dedicated to evolution. There is not a single one outside the most conservative Christian colleges that wants anything to with ID or creationism. Virtually every major scientific organization in the country has issued statements condemning ID and creationism and endorsing the importance of evolution in their disciplines. Not a single one wants anything to do with ID.
This needs to be explained. You can argue, as ID folks do, that this uniformity of opinion reflects a vast atheistic conspiracy that just won't let a group of hardworking free thinkers catch a break. Or you can consider the possibility that just maybe scientists know what they are talking about, and that their support for evolution and condemnation of ID reflects the consistent success of the former against the bankruptcy of the latter.
Which do you find more likely?
[Last modified October 20, 2007, 19:36:41]
[an error occurred while processing this directive]