Because most philosophies that frown on reproduction don't survive.

Tuesday, June 19, 2007

The Edge Between Evolution and... What?

One of the more positive reviews of Michael Behe's new book The Edge of Evolution: The Search for the Limits of Darwinism appeared in Crisis Magazine, and was authored by senior Discovery Center fellow Benjamin Wiker. (His author bio on the review itself doesn't mention his Discovery Center affiliation, but he's listed on the DI site here.)

I'll admit that I'm not rushing to make time to read Behe's newest effort. I've not been terribly impressed with what he and the ID crowd have had to say in the past, and my "to read" pile is pretty deep right now. So this cannot pretend to be a critique of the book itself. However, one of the underlying assumptions of the review struck me as very interesting, and I'd like to look at it for a moment here.

In his first paragraph, Wiker says:
Function, for Darwinism, is the true test. If a particular trait doesn’t contribute to survival, it won’t be selected by nature, and hence won’t be preserved in the organism and passed on to future generations. But since Darwinism posits the gradual building up of complexity piece by minute piece, it is demonstrably impossible for it to provide several well-matching parts at once. Therefore, Darwinism fails, and having failed, it must cede its place in explanation to the default position, Intelligent Design.
Two interesting things go on in this paragraph.

First there is an incorrect statement of how selection acts upon traits in a population. Wiker states that if a trait doesn't contribute to survival, it won't be selected and thus won't be preserved in future generations. It's easy to see what he's thinking of here, but his mis-understanding (or failure to express himself clearly) is actually rather key. I have straight, dark hair, but there is no reason to believe that this trait is being selected for in me. And yet, my daughters also have straight dark (though not as yet quite as dark) hair. This trait has been passed down to the next generation even though it has no selection advantage. Some traits are even passed down which are actively dis-advantageous. For instance, both my parents had to wear glasses, and so do my sister and I. Clearly, poor eyesight is being passed down in our family -- and so there's a decent chance that some of my children will suffer from the same defect. However, poor eyesight has done little to detract from our chances of procreation, and so the trait is merrily passed on to successive generations. This may seem like a relatively minor point, but it's actually a very important distinction between the school book explanation of evolutionary theory and reality. It is not the case that any trait which crops up in a population must be actively advantageous in order to be passed on and remain in the population. It just has to not be sufficiently dis-advantageous under current selective pressures to be weeded out. This allows for much more variation within a population than Wiker seems to be allowing for.

The second interesting thing going on in this quoted section is his comment "Darwinism fails, and having failed, it must cede its place in explanation to the default position, Intelligent Design". Perhaps this seemed like an easy sell to a conservative, Catholic audience. ID usually gets pretty softball treatment in conservative publications because it's proponents tend to be conservative Christians themselves. However, one does well to look a little more closely at Wiker's statement here.

At first blush, he seems to be saying something almost silly: "Either something is explained by Darwinism or it's explained by Intelligent Design." And yet clearly, there are a host of things which are explained neither by 'Darwinism' nor by Intelligent Design. Which of these two is responsible for gravity? Nuclear fission? Tornadoes?

However, I think that probably Wiker was simply using a bit of shorthand here, and meant either to restrict himself to speaking only of change within and between species, or perhaps instead to assert a more general principle that everything is the result either of intelligent design or of what might be termed "purely naturalistic forces". And yet, it he means to say the first of these, he's engaging in the rather sloppy debating tactic of "Either you are right, or I am right. You are wrong, and therefore I am clearly right." Unless one gives any strong reason for believing that the point in question is binary, this is not cricket. If he means the latter (which is, the best I can made of the matter) then we have something even odder.

I realize that Intelligent Design makes a great point of saying that it does not purport to know anything about the designer which it posits. And yet let's be honest here: The point of interest to both me and Wiker (and Behe for that matter) is whether God's hand can be seen in the world. And yet what exactly does it mean to say that something is the result either of natural forces or intelligent design? Isn't that to suggest that "natural forces" are somehow not the workings of God's will, and that the workings of God's will are sufficiently sudden and inexplicable to defy "natural" explanation?

It seems to me that there is some very bad thinking that has been going on since the Enlightenment (I often think that the discovery of Newtonian mechanics may have been one of the inciting ideas in this regard) to which many modern Christians are all to ready to fall prey.

The understanding of nature which was held by St. Thomas Aquinas, and which allowed the Catholic Church to nurture much of early science, is that God's will is a rational and ordering principle guiding the universe. It is thus because of God's ordered nature that object in the universe move in ways that can be calculated and predicted mathematically, and because of God's will that creatures descend from each other via methods that are explicable to reason. The Christian worldview has traditionally held that the world is explicable to reason because God, the creator of the world, is Himself reasonable.

However, ID proponents seems to have latched onto a far more modern understanding of "nature vs. God" and thus feel that in order to feel confident that God is the creator of the universe, there must be clearly identifiable points at which "natural" laws and processes explicable to reason do not appear to apply.

This seems to be what Wiker is moving towards with the conclusion to his piece:
Evolution happened, and Behe has no problem with sharing ancestors with apes. The question is not whether evolution happened, but whether mere random mutation and natural selection can explain it. Since it cannot, then the vast panorama of life must be explained by nonrandom—that is, intelligently guided, or at least front-loaded—evolution.
He is clearly ready to concede evolution and common descent (whatever exactly that is taken to mean in the situation he is describing here) but feels it important that there be signs of divine tweeking in the process. And yet, if God created the processes by which creatures vary and are selected, would it not be reasonable to believe that His handiwork would be consistent throughout? If we are right in our worldview, things do not trundle along their natural way without God's help. Rather, what we see as natural laws and processes are the working out in nature of God's constant and rational will.


John Farrell said...

Well said, Brendan. I think I would fall off my chair if there was a positive review of an ID book that wasn't penned by someone on the DI's payroll.

Having said that, Jason Rosenhouse makes a good point on his blog that Jerry Coyne's savage review of Behe's book was counterproductive to say the least.

Razib Khan said...

Function, for Darwinism, is the true test. If a particular trait doesn’t contribute to survival, it won’t be selected by nature, and hence won’t be preserved in the organism and passed on to future generations.

on the molecular level a lot of neutrality or near neutrality seems operant. as for traits, if the selective value is neutral, the likely of loss is high over time, but if most traits are neutral then you'd have a consistent turning over of neutral traits over time.

Steve Bodio said...

I'm going to try the new Ayala book Darwin's Gift: to Science and Religion). NON ID reconciliation between religion and science, and from the reviews an amusing criticism of "design" over such imperfect structures as the human pelvis 9for birth) and back. (Would designed features be imperfect?)

CMinor said...

Only had time to skim tonight--but I wanted to say I thought your explanation of the heritability of non-advantageous traits was well said. I've tried, on occsasion, to explain that it's not survival of the fittest, it's propagation of the adequate!

From one reproductively adequate myopic to another.

Arimathean said...

Yeah, the ID folks implicitly assume a mutual exclusivity of the natural and the supernatural - that you can't get more of one without getting less of the other. Thus, they look for gaps in nature where they can posit the presence of the supernatural.

But the god of the gaps is not the God of Christianity. And I don't see how one could reconcile the mutual exclusivity of the natural and supernatural with the Incarnation: If Christ was both fully God and fully man, then it would seem that the supernatural can be present in the physical world without displacing or precluding the natural.

The Opinionated Homeschooler said...

My vague recollection of BIO 302 is that natural selection no longer applies to humans; thus we see the passing on of undesirable traits, the existence of genuine biological altruism (e.g. choosing celibacy to devote one's life to the children of other people), etc. Culture and consciousness were the culprits, if I recall.

However there are several species of birds in which the females prefer--for unclear reasons--certain traits in choosing a male that are so disadvantageous as to bring the species near extinction (I think there was one species mentioned that had already been driven into extinction by the females' preference for large, weighty, purposeless tailfeathers that made it impossible for the males to escape predators).

Now one could say that the disadvantageous traits were still advantageous for survival, since the females would only breed with males showing those traits; but that seems to bring one close to begging the question.

Darwin said...

Opinionated Homeschooler,

Well, it depends. There are some famous instances where natural selection does apply: such as the higher incidence of sickle cell anemia in populations frequently suffering from malaria.

Generally speaking, many natural selection factors are mitigated by human itelligence and culture, but I don't think one would say that it doesn't apply any more.