I think you're right that providing the Darwinian rationale for a self-help regime can sometimes inspire compliance with it. There is something about a grand unified theory of human nature that lends power to advice even when grasping the theory isn't a logical prerequisite for following the advice. And the grand unified theory underlying Mean Genes has the additional advantage, as they say, of being true.
But Slate's editors would be very annoyed if we dwelt on our areas of agreement, rather than bickering. So let me stubbornly persist on this theme of how in some cases, at least, knowing thyself doesn't yield a very clear path to self-improvement. And let me suggest that these cases are a bit more common than one would gather from reading your book.
One standard misconception about modern Darwinism that you have no doubt encountered is the fallacy of conscious calculation: Evolutionary psychology, some people think, holds that humans are designed by natural selection to go around consciously, rationally, thinking about how to get their genes into the next generation. Uninformed critics of the field, such as the British scholar Roy Porter, point out triumphantly that people enjoy sex even when they're using contraception—so how could sexual psychology be about spreading genes? The answer, of course, is that in the ancestral environment there was no contraception, so genes that made sex pleasurable thrived. Those genes are still at work today, oblivious to contraceptive technology.
This, I think, helps explain why conscious, rational Darwinian self-understanding doesn't easily translate into self-control: Our genes' agenda isn't being pursued at the conscious, rational level in the first place; instead, the genes impose their hidden logic largely by governing our feelings (and by covertly biasing our thoughts and perceptions in ways I'll come to). Go explain to some unfaithful, contraception-using husband or wife that their lust is absurd—it was designed to pass on their genes, which it's now failing to do. They'll reply: Well, maybe, but knowing about the absurdity doesn't make the urge any less strong, any easier to resist. Or go to some young man spending his spare time downloading pornography rather than dating real, live women, and explain the Darwinian absurdity of his behavior. He'll say, "Thanks for sharing that. Could you pass the Kleenex?"
So too with road rage, the demonizing of professional rivals, and on and on: I know the underlying impulses were designed for the purpose of genetic proliferation; I know that in the modern world they're not succeeding even on that score—and that, more to the point, in most cases they're not making me happy. But, though this knowledge may help a bit, these feelings remain pretty stubborn.
I realize you're aware of this general problem. For example, mindful of the slippery slopes via which our genes pull us into trouble, you and Jay Phelan suggest that married men might avoid having even an innocent-seeming lunch alone with a woman. (Billy Graham, by the way, made this an ironclad rule, which is one reason he didn't turn into Jim Bakker or Jimmy Swaggert.) Indeed, if you asked me the question I asked you—what good does it do people to know about Darwinism—I'd defend your book as follows: Understanding that our impulses are truly animal in strength helps us realize that extreme measures, such as the Billy Graham rule, may be required to win the battle. I agree with you that sometimes, at least, our genetically based desires should be thought of as "the enemy," and a very tough enemy.
Still, I do think you sometimes underestimate the enemy's subtlety. Consider the closing words in your chapter on infidelity: As a marriage wears on, a man or woman should imagine his or her spouse "at a cocktail party, enchanted by the witty, smart, vibrant person across the plate of hors d'oeuvres. Is that charmer you? At some point it was. And as long as we remain interesting dynamos, there will be no conflict between monogamy and our infidelity-promoting mean genes."
This strikes me as a bit too simple. Thanks to human nature, marriages face unfortunate asymmetries. One, as your book notes, is that men find youth a particularly central part of sexual attractiveness. Another is that husbands are still fertile, and accordingly lustful, in late middle age, whereas wives typically aren't. Together, these give an aging couple a mismatch of interests that won't be resolved simply by the wife's remaining an "interesting dynamo" (even assuming she considered hanging on to her husband worth the trouble).
Will the husband's understanding of Darwinism help keep him from straying? Conceivably. But, this Darwinian self-knowledge should include something your book doesn't much explore in this particular context: that our genes impose quite subtle biases on our "rational" thought. If a husband's genes "want" him to cheat on or even leave his wife, they may lead him to concoct elaborate excuses. (As may the wife's in the reverse situation.) For example: He'll convince himself that his wife isn't the "interesting dynamo" she once was—whether or not, in objective reality, she is.
As I've said, I think Mean Genes has a lot of very good advice, especially about how to manage our animal impulses. But do you agree with me that the problem of human nature goes well beyond the obviously animal impulses—that our genes bias our perceptions and our "rational" thought and even our moral intuitions in subtle and often pernicious ways?