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Coyne vs. Nelson [EvolutionBlog]
Jerry Coyne has an interesting post up reporting on an e-mail he received from Paul Nelson. Nelson is a prominent young-Earth creationist, though he also circulates freely among the ID folks. Nelson, annoyed by Coyne’s emphasis on the importance of natural selection in evolution, sent Coyne an e-mail, part of which I now reproduce:
Skepticism about the efficacy of natural selection is widespread within evolutionary biology (see below). Jim Shapiro is hardly alone in this regard. So when you tell your WEIT audience that natural selection is the only game in town for building complex adaptations, you can expect two consequences:
1. Readers who already know about the thinking of workers such as Eric Davidson, Michael Lynch, Andreas Wagner, John Gerhart & Marc Kirschner, or Scott Gilbert (all of whom, among many others, have recently expressed frank doubts about selection) must discount what you say about the centrality of natural selection to evolutionary theory — because they know that just isn’t so.
2. Readers who do not already know about Davidson, Lynch, etc. — upon coming across their ideas — must wonder why you told them that natural selection is the sine qua non of evolutionary explanation.
Either outcome is bad.
Now, it just so happens that Jerry personally knows all of the folks whose names Nelson so gamely dropped. So he sent out an e-mail, letting them know that their work was being used in support of anti-evolution arguments. You can find their replies in Jerry’s posts. I’ll let you go to Jerry’s blog to read them, but I’m sure you can guess how things went.
Nelson could not have been more clear that he was talking about the ability of natural selection to account for complex adaptations. And, as is equally clear from Jerry’s reporting, none of the gentlemen Nelson cites challenge the ability of natural selection to craft such adaptations. They might challenge this or that esoteric aspect of modern theory, but when it comes to the points at which anti-evolutionists direct their fire they are in agreement with traditional theory. Complex adaptations arise gradually under the auspices of natural selection.
In some cases what is being challenged is “adapationism.” That is, someone might agree that natural selection accounts for adaptions, but also believe that much of evolution is non-adaptive. In that sense they might be downplaying the centrality of natural selection. In other cases people are suggesting that modern genetics is revealing that variation is a more complex phenomenon than traditional theory allows. However, regardless of the origins of the variations, they must still pass through the sieve of natural selection. Still others are pointing to the renewed emphasis on development (embryology) in evolution, which had largely been ignored by the founders of the Modern Synthesis. But, again, this is an enrichment of textbook theory, not a repudiation of it.
Nelson showed up in the comments thread of Jerry’s post, and an interesting discussion ensued. I recommend browsing through it; it won’t be hard to distinguish the interesting comments from the standard ranting. Nelson produces various quotes from the authors he cites, while others explain patiently why those quotes don’t say what Nelson needs them to say. Throughout the discussion, two points became clear to me.
The first is that, in light of the responses given to Jerry by the scholars whose work Nelson cites, it is clear that they do not at all challenge either the efficacy of natural selection in crafting complex adaptations, or the centrality of selection in evolution in any sense that would be helpful to anti-evolutionists. Any attempt to use their words to make it seem they are saying otherwise must, therefore, be a misrepresentation.
The other point, however, is that it is simply bizarre for an anti-evolutionist to use these authors in the manner Nelson attempts to do. You see, to the extent that they are challenging textbook theory, it is in the direction of saying that the Modern Synthesis unreasonably limited its explanatory options. They are not saying that there are fundamental problems that modern theory can’t explain, and that we must consequently grope around for some new theory. They are saying instead that the palette of evolutionary explanations includes more than the architects of the synthesis realized.
I am not qualified to judge the merits of their claims in that regard, but if they are right that is far worse for ID and creationism than it is for evolution. If the critics are right then natural explanations are even more fecund and productive than previously thought. Accepting all of their arguments does not at all suggest we must resort to the invocation of a designer to account for biological complexity. Quite the opposite in fact.
Moving on, the e-mail Nelson sent to Jerry also includes a link to a talk Nelson recently gave at Rick Warren’s Saddleback Church. I have now listened to that talk (the video did not seem to be working, so I had to settle just for the audio.) Nelson opens with some bravado about how he is going to present completely incontrovertible evidence of design in nature. In light of the confidence of this opening, it is surprising that he provides only a single scientific argument. He argues that natural selection cannot account for the fundamentally different body plans we see in nature.
Early in the talk he refers to worms, flies and sea urchins as examples of fundamentally different body plans, and says specifically that it is very difficult to “interconvert” between them. His basis for this assertion is that the basic body plans are laid down early in development, meaning that, to alter them, natural selection would need to work on mutations affecting early development. But, as studied in modern organisms, such mutations are nearly always fatal, because their effects cascade throughout the process. Mutations affecting the later stages of development might change incidental characteristics of the organism, but the fundamental body plans will not be altered.
Now, let us leave aside the philosophical dubiousness of presenting a single challenge to one aspect of modern theory as clear evidence for design. Regarding the argument itself, it sure seems to me that Nelson has overlooked something simple. No evolutionist is talking about “interconverting” one modern organism into another. No one is trying to change a fly into a sea urchin. Obviously, if you have a modern, highly complex, organism and start messing with its early development, it’s going to be very difficult to make a beneficial change. But that’s not at all what evolutionists need for the theory to work.
The fundamental body plans were laid down very early in the evolutionary process, and those first mutations that set flies down their paths and sea urchins down theirs would not have looked like dramatic macromutations at the time. In fact, they would have been hard to recognize, at that time, as mutations of fundamental importance. So I don’t see how Nelson’s argument provides much reason for doubting the ability of evolution to account for the various different body plans. Once these plans are in place, fundamental change becomes difficult and evolution inevitably gets channeled into just a few directions. But even large transitions, like those between land-dwelling quadrupeds and whales, or between reptiles and mammals, both well-documented in the fossil record, do not require changes in the fundamental body plans.
Nelson’s talk features a second argument. Early on, Nelson quotes Bertrand Russell as saying that there was insufficient evidence for believing in God. The audience chuckles at Russell, fancying themselves more clever than he. But this leaves the question of why it is that so many really smart, savvy scientists, people who really know their subject, do not find Nelson’s evidence for design to be persuasive. They could all be wrong, but they can’t all be crazy or stupid.
Nelson argues that the commitment of science to methodological naturalism (MN) blinds scientists to what is put so plainly before them. It is a requirement of their profession that only naturalistic explanations are acceptable, you see. We are to believe, apparently, that this requirement is so blinding that they are unable to see things that are obvious to Nelson’s more clear-thinking audience.
This is the standard ID explanation for the popularity of evolution among scientists. It is, sadly, a ridiculous argument. As I explain in Chapter 20 of Among the Creationists, I have my problems with some of the rhetoric people on my side have used in defense of MN. But even if we accept Nelson’s characterization of it as a hard and fast rule, the fact remains that there is no requirement that scientists slavishly accept any old naturalistic explanation that comes along. It’s perfectly acceptable to say we don’t have a scientific explanation for the origin of species.
Moreover, being a scientist is not the entirety of anyone’s life. Scientists could agree that when practicing their profession they accept the constraints of certain conventions, and that invocations of supernatural intelligent designers are not part of their professional lives, while also believing that the evidence points strongly to an intelligent designer. But that is not what is happening. Scientists are not all mopey and dejected because their profession requires them to accept evolution when privately they think it’s a weak theory. Instead it is defended enthusiastically by virtually everyone in the relevant areas of science, while Nelson’s arguments are dismissed angrily not just as unscientific, but as totally worthless on the merits.
There is, I would think, also a theological problem with Nelson’s argument. On the one hand, he claims that the evidence for God’s existence is so overwhelming and unambiguous that anyone who has not been blinded by ideological prejudice can see it clearly. But the fact remains that the evidence Nelson cites is not thought to be persuasive by the vast majority of professional scientists, the folks, mind you, who really understand this subject backward and forward. This includes a great many Christian biologists who, while certainly not laboring under an anti-supernatural bias, nonetheless think the evidence Nelson presents is a poor reason for believing in God.
So what is God playing at? Does He want His existence to be completely obvious or not? If He does, then why does He leave clues that are, for the most part, persuasive only to people who know little about science? And if He does not, perhaps so that we may be said to have a free choice about coming to faith, then why does He leave such powerful clues at all. In his talk, Nelson suggests that all evidence gets filtered through the biases of the person interpreting it, so that mere quantity of evidence is not really what matters. This is fatuous, of course. Yes, we all suffer under the weight of our biases and preconceptions, but most people are not so dogmatic in their beliefs that absolutely nothing can change their minds. Prior to Darwin, most scientists accepted Paley’s design argument as entirely convincing. The evidence presented by Darwin and his successors caused most people to change their minds. If God wants His existence to be completely obvious, I have no doubt he could manifest Himself in ways that would convince virtually everyone. He would not need to rely on clues that are compelling only to those who do not know what they are talking about.
2012-12-19 01:40:08
Source: http://scienceblogs.com/evolutionblog/2012/12/19/coyne-vs-nelson/
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