13 February 2010

Signature in the Cell: Chapters 4 and 5 - major themes

Chapter 4 is called "Signature in the Cell." It's an important chapter for two reasons. First, along with chapter 5 ("The Molecular Labyrinth") it lays out Meyer's central question by pointing to the specific features of cellular information systems in need of explanation. Second, it exemplifies an aspect of ID thought that I want to highlight. I'll discuss these two themes here, then add some further critiques in a second post.

1. Meyer's central question Each chapter can be summarized in a short paragraph. Chapter 4 asserts, correctly, that cellular information systems (DNA most notably) exhibit "specified complexity," by virtue of containing "specified information," which is information that is "specifically arranged to perform a function." (Definition is on page 107.) Chapter 5 asserts, correctly, that the information in DNA requires an information-processing system in order to be usable. This information-processing system is itself encoded by DNA, and so any explanation of the origin of cellular information systems faces a chicken-and-egg problem. The DNA is necessary for encoding the blueprint for making the information-processing system, but the code is worthless without the information-processing system. So which came first, the DNA or the processing system? How could either have arisen alone, given that neither can exist without the other?

Both chapters include engaging accounts of the efforts to describe and understand molecular genetics in the epochal years just before and after Watson and Crick announced their model for DNA structure. As I've mentioned before, one can read all of this elsewhere, but Meyer's treatment is interesting and – as far as I can tell – accurate. And Meyer is right when he says that these extraordinary phenomena require explanation. He's right when he says that the origin of integrated complexity of cellular information systems (and all other cellular systems) seems very difficult to explain. He's right about specified complexity, and his emphasis on the difference between mere complexity and specified complexity is important, even crucial. This is the key point of Chapter 4.

Chapter 4 begins with a brief introduction to the nature of information, discussing Shannon's theory of information. Meyer makes the distinction between "information-carrying capacity," which can be measured using Shannon's ideas, and "information content," which can't. These strike me as very basic concepts and distinctions, but they're important: we can't make sense out of claims about "information" until we know what it is we're talking about. And that is likely to be a problem as we continue examining this book. Because according to Jeffrey Shallit, the notion of "specified complexity" doesn't exist in information theory. It's a commonsense claim about "function" or perhaps "meaning" that is used almost exclusively by ID theorists, and critics of ID note correctly that the shifting between mathematically-rigorous concepts of information and folk notions of "specified information" leads inevitably to confusion and to, well, misinformation.

Now, I'm a biologist and not an expert on information theory, so I'm willing to give ID thinkers a bit of a break on this one. I don't mean that I will overlook misleading rhetoric or overt errors; I do mean that I think there's value in identifying those aspects of genetic information that give it the appearance of design. Design, after all, is the question. We do need concepts like "specified complexity" in order to identify that which we seek to explain. This is the point that Richard Dawkins makes so forcefully in The Blind Watchmaker, and I think it's a big mistake to under-emphasize the reality of biological design. Design is the question! In other words, I think that the ill-defined concept of "specified complexity" is useful for defining what we mean by "design," and that its nebulousness is something we'll all have to live with for now. I have to live with it. So does Meyer, and he will have to be careful to make it clear that he has not rigorously or mathematically defined that concept. (Side note: I think that fans of ID probably underestimate the potential for serious confusion that arises when precise mathematical or scientific terms and concepts are mixed with "common sense" or "intuition." The result is almost always folk science, and by far the biggest challenge for ID theorists is to convert their currently useless folk science into actual explanatory theory.)

So anyway, chapters 4 and 5 tell us what Meyer wants to explain.

2. ID and the "oh wow" factor I've previously discussed a habit that ID thinkers exhibit that I believe is both a key problem for the movement and a clear aspect of its psychology. Meyer includes detailed descriptions of biochemical processes and structures, descriptions that do not contribute to his case. He enthuses about the structure and function of RNA polymerase in detail, and adds textbook descriptions of ribosomes, aminoacyl-tRNA synthetases, and the roles of ATP in powering biochemical reactions. There's nothing wrong with geeking out about biochemistry (I can play this game as well as anyone), but there's something fishy about these performances, especially when they're played out for laypeople. At some point, the heaping on of gory details looks like an attempt to overwhelm the layperson with the sheer complexity of cell biology, until the poor reader, repeatedly gasping "oh wow," just surrenders to the impulse urged from the beginning by our pattern-recognition-obsessed brains: "Dang. It can't just happen."

Some will find this obnoxious, but I think that's the basis of the appeal of ID in the first place: our understandable human impulse to identify – even seek – agency. We want to see design; it's completely natural. One way to get us there is to just keep pushing, and pushing, and pushing, with examples of the spectacular complexity of biological structures. Richard Dawkins tried to meet this challenge head-on in The Blind Watchmaker. It's the whole point of the book. Yes, the biological world is amazing, exhibiting design and optimization that can and should boggle the mind. But that incredulity should not supplant explanation; our ignorance, even our awe, must not lead us to abandon our secondary urge to understand and to explain. Readers of Signature in the Cell, like readers of Michael Denton's Nature's Destiny and of Behe's books, should beware of this ploy. Awe and wonder are God-given human capacities that we should all exercise and celebrate; when they mutate into unimpeachable personal incredulity, they spawn cancers of ignorance.

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