David Sloan Wilson, over at the Huffington Post, has replied to my criticism of his previous essay on why the so-called “invisible hand” guiding financial markets is, as he puts it, “morally, ethically, spiritually, physically, positively, absolutely, undeniably and reliably dead.” David and I have a good working relationship (he is one of the infamous “Altenberg 16”) and mutual respect, so the following is meant to be in the spirit of an open minded debate between two scholars. David agrees, contrary to many of our colleagues, that it is good for the public to see scientists honestly argue their diverging positions in public, so here it goes.

First off, David claims that both conservative commentator Larry Arnhart and I “have objected to [David’s] declaration that the invisible hand is dead.” Arnhart has, I certainly have not. I completely agree that this pernicious idea has gone the way of the dodos in light of the events of recent years (at least from the Enron debacle on). I simply disagree that such a conclusion has anything whatsoever to do with hypotheses on the evolution of human morality and cognitive abilities.

Wilson challenges my claim that evolutionary psychology cannot tell us much, as a science, about the evolution of social human behavior. He rhetorically asks “Would [Massimo] make the same claim about astronomy, geology, and paleobiology? Past events leave traces in the present that can be pieced together to produce solid knowledge.”

Of course they do! I, like David, am an evolutionary biologist, and I am perfectly cognizant of the inferential power of historical research. But I am also well aware of its limitations. Astronomy, geology, paleobiology, as well as much of evolutionary biology, have plenty to say about historical events, and they are solid sciences. The case for the evolution of human cognitive (as opposed to physical) traits, however, is much more dicey.

David wants a full account of the reasons for my skepticism, and he can find them in Chapter 7 of my book with Jonathan Kaplan, Making Sense of Evolution. Briefly, the problem comes down to three accidents of history that make it particularly difficult (though I never used the word impossible) for scientists to test historical hypothesis about cognitive adaptations in humans:

a) We do not have a fossil record of the relevant behaviors (as opposed to, say, physical attributes like brain size);

b) we do not have enough closely related species for a statistically sound phylogenetic comparative method to apply;

c) it is irrelevant to measure natural selection on currently existing populations because the environmental conditions are radically different from those under which the traits of interest evolved.

These problems do not apply in the case of several other species of living organisms, where one or more of the above conditions are satisfied, and the testing of adaptive hypotheses can therefore proceed on firmer ground. None of this, of course, means that evolutionary psychologists are wrong in their theories, it just means that their suggestions ought to be taken with a huge grain of salt, as arguments from plausibility, not established science.

Wilson also mentions the fact that there are plenty of peer reviewed papers in evolutionary psychology, but I find this to be by far his weakest argument. Peer review is a necessary component of scientific practice, but it is only the beginning of the critical analysis of scientific claims, not the end. Plenty of wrong ideas (e.g., the ether theory) have succumbed despite once being published in peer reviewed journals, and I’m not even going so far as claiming that evo-psych’s ideas are wrong, just not firmly grounded in historical evidence!

David’s more interesting point is that “all theories of human behavior require assumptions about an underlying human nature ... asking where the assumed propensities come from, the only plausible answer (barring creationism) is to provide an evolutionary account.” As he knows very well, I do not subscribe to creationist ideas, so why exactly is he bringing this up? I submit that his premise his incorrect: we do not need a theory of the origin of “human nature” (a concept in itself fraught with philosophical and scientific problems) in order to study the behavior of human beings in modern societies.

I hasten to clarify that I am no simple-minded behaviorist, but I simply do not see what could possibly be added to modern cognitive science by speculations on whether certain behaviors evolved by natural selection. Whether they did or not (and as I pointed out above, it is exceedingly difficult to tell), we can quantify the behaviors, model them, and even make testable predictions about their consequences for individuals and societies.

Since the issue here, remember, is what one ought to do with respect to market regulation, any scenario based on a possible evolutionary historical path rather than another is simply not that relevant.

Finally, to the naturalistic fallacy (deriving an ought from an is), which I claimed both Wilson and Arnhart committed in their respective commentaries. David cites the extended comments of thinkmonkey on this blog to exonerate him from having committed the fallacy, stating that “I did not say that sustainable society is good because it evolved in our species.”

Okay, there clearly is plenty of room for subjective interpretation here, and if David says that’s not what he meant, I’ll take his word for it. But if that is the case, why then does he start his reply to me with “my main argument against the invisible hand is based on fundamental evolutionary principles ... If there is anything that we can say with confidence, it is that individual selfishness does not automatically lead to adaptive societies.”

Perhaps, but adaptation is a matter of biological fitness (survival and reproduction), which is not at all the same thing as morality and justice. If David doesn’t want to mix the two, why does he build an argument for a particular moral choice (we should regulate the markets so that they don’t wreak havoc on people’s lives) on the basis of a fact about the a-moral concept of biological adaptation? Once again, evolution does not have much to say about the current debate on Capitol Hill, and bringing it up doesn’t help either policy makers or the public at large.