03 Oct 2009

Manzi on Evolution

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Jim Manzi is by far my favorite writer on the nuts-and-bolts of the climate models. After reading relevant sections of the IPCC AR4, I thought I had a pretty good idea of how the simulations actually worked, but I wasn’t totally confident until reading this Manzi piece.

Anyway, I recently checked out his archives at The American Scene. If you have never read Manzi, I encourage you to skim his posts and see if anything grabs you. I was very pleasantly surprised to see that he has (perhaps foolishly for his credibility in our secular age) dived into the evolution debate. In particular, I really liked his response to evolutionary biologist Jerry Coyne, who (in a book review of somebody else) had given the grandiose claims about “thank goodness Darwin set those self-important Bible-thumpers straight!”

Now note that I’m not saying Manzi is 100% in the post linked above; I think at times he overreaches. But even so, he does a great job dismantling some of the more absurdly over-the-top claims that are often put forward by evolutionary biologists in this type of debate.

I had wanted to get hip-deep into these issues, with Coyne’s claims, Manzi’s proferred counterexample, my commentary, etc. But I have been so busy, I know that’s not going to happen anytime soon. Instead let me just give you Manzi’s concluding paragraph:

The theory of evolution, then, has not eliminated the problems of ultimate origins and ultimate purpose with respect to the development of organisms; it has ignored them. These problems are defined as non-scientific questions, not because we don’t care about the answers, but because attempting to solve them would impede practical progress. Accepting evolution, therefore, requires neither the denial of a Creator nor the loss of the idea of ultimate purpose. It resolves neither issue for us one way or the other. The field of philosophical speculation that does not contradict any valid scientific findings is much wider open to Wright [whose book was under review] than Coyne is willing to accept.

Incidentally, in making his case, Manzi discusses in some detail a “genetic algorithm.” I asked Silas Barta what he thought of Manzi’s case, since Silas knows a lot about information theory. (See this post on Intellectual Property, and Silas’ clever example, to see him deploy information theory in a different context.) Anyway, below is Silas’ response to Manzi’s column, and of course Silas does not necessarily agree with anything I am saying in the present post:

-I’m a bit disturbed by how Manzi didn’t discuss the local optimum problem, where a genome isn’t the best overall, but is better than all the other candidates and yet can’t be improved without radical revision. This means that a genetic algorithm, like all general optimizers, is not guaranteed to find the global optimum on an arbitrary problem. In the example of the 100 switches, it may reach the solution slower than randomly iterating through them, which often plagues those who have high expectations of GAs. This is mentioned in the link he give[s] to Talk Origins.

(GAs are way overrated, by the way; they don’t on average do better than the other optimization methods like simulated annealing, hill-climbing, etc.)

Because you’re probably wondering about it: yes, that means that evolution of earlier life by no means guaranteed humans evolving, or indeed any intelligent species capable of culture.

-Scientists do indeed claim that evolution has no long-term purpose, but…this just means that they don’t believe they gain in predictive power by assuming it works toward some long-term purpose. However, they claim that evolutionary processes have the effect of attempting to maximize the fraction of the gene pool that any given gene represents. Manzi is correct to note that the constantly-shifting fitness landscape (what’s optimal for animals living near wolves isn’t optimal for animals living near ducks, etc.) and massive multi-directional interplay of factors make it effectively impossible to say *which* genes will increase in frequency in advance.

-As for Manzi’s general theme about the purpose of the universe being outside the realm of science, I would say that under some circumstances, scientists would be able to identify a purpose, but the dynamics at play in the universe as we know it make it currently impossible for science to say one way or the other.

UPDATE: Oh I should also mention that another flaw in Coyne’s typical critique against medieval Christians, is that Coyne gets his timeline screwed up. Gene Callahan pointed out (in email) that it wasn’t Galileo but Kepler Copernicus [my dumb typo, not Gene’s–RPM] who had “announced” that the earth wasn’t the center of the universe. Furthermore, as reading Dante etc. indicates, medieval Christians didn’t think it was noble to be at the center of things; that’s where Hell was!! (Gene may have to clarify in the comments if I’ve botched his critique of Coyne.) So this standard debating ploy of “Christians can’t accept Darwin because of their fragile egos” is based on bogus Church history. Yes, it’s certainly true that modern Christians don’t like being told, “You’re not special, you serve no divine purpose, you are a statistical fluke,” but the ‘history’ given to buttress that charge is bogus.

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