Yesterday, shortly after I filed the first installment in our exchange, I tuned in to CNN and saw Ted Williams' daughter complaining that her half-brother has frozen Williams' body and hopes to sell his DNA. That seemed so eerie that I started to see your side of this issue: Maybe reproductive cloning should be banned outright. But then I thought, wait a second—just because something makes you briefly nauseous doesn't mean it's wrong. So I started to try to articulate a good, rational argument against selling Williams' DNA to women who want a son with 20-10 eyesight and quick wrists. So far I haven't gotten very far. (How different is this act of female reproductive choice from the act of choosing an athletic husband with whom to procreate? OK, pretty different, I guess—but what exactly is bad about the way it's different?)
Anyway, it occurs to me that this is one big difference between you and me: You seem to think that if something feels viscerally wrong, that by itself is good evidence that it's immoral. Or, at any rate, you attach a degree of validity to our moral intuitions that I don't. According to evolutionary psychology, some of our moral intuitions—e.g., that retribution is good in and of itself—are with us simply by virtue of the fact that in the past they helped our ancestors get genes into the next generation. This is hardly a ringing endorsement of them, especially given that this is something they seem to share with, say, the urge to murder or rape under some circumstances.
Your deep respect for the natural order comes through in Our Posthuman Future in passages like this: "The moral reasons [to ban cloning] have to do with the fact that cloning is a highly unnatural form of reproduction that will establish equally unnatural relationships between parents and children." As if the natural dynamics between parents and children couldn't be improved on! According to evolutionary theory, the Darwinian interests of parents and children naturally clash, and this can lead to much unpleasant psychodrama. It may be in some sense "natural" for a man to leave his post-menopausal wife for greener pastures, even if that leaves his kids eternally bitter. Surely you don't denounce lifelong monogamy—as you do cloning—on grounds that it violates the "natural" order.
When we move from cloning to genetic engineering, and for that matter psychopharmacology, your book's respect for the "natural" still strikes me as problematic. It's in some sense "natural" to hate people, to manipulate people, to deceive people—and to deceive ourselves in order to deceive others better. I walk around fairly conscious of these lamentable proclivities—yet I still find them hard to surmount. If a pill, or a transplanted gene, could make me a better human being, I'm not sure on what grounds I'd refrain from it.
Of course, when you warn that human nature is complicated and meddling with it will have unintended consequences, I'm with you. Also, in my experience, just about every pill has a downside that's at least equal to its upside. Still, I don't object in principle to using biotechnology to make us better people, whereas you seem to.
Much of our disagreement gets back to the "naturalistic fallacy"—using nature as a moral paragon, inferring "ought" from "is." You deny that this Philosophy 101 fallacy is in fact fallacious. But that's one we're not going to solve in the brief time and space allotted here, so I'll just direct philosophy buffs to your book for elaboration, register my skepticism, and move on.
On to the Extropians! You deny that the theoretical island-nation of Extropia could defeat the purpose of a national cloning ban by providing a cloning salon for rich Americans. And it's true that a few investment bankers Xeroxing themselves wouldn't be a big deal in the scheme of things. But suppose we change the subject from cloning to genetic engineering. There the scariest long-run scenario, for my money, is precisely that rich people will have designer babies and others won't—so we could see the eventual evolution of a race of super-healthy, super-smart humans (as if rich people, given their awesome capacity to circumvent the meritocracy, needed actual merit!). Wouldn't you agree that a genetically distinct elite class is a harrowing prospect even if—maybe especially if—the class is pretty small? Ergo, that any international regulation of germ-line engineering that fell short of fully global regulation would be woefully inadequate? (Presumably the prospect of the Extropians breeding a super-race that could take over the world gives you pause, given their tendency to trash copies of your book.)
Speaking of genetic engineering: Much of your argument against reproductive cloning seems to be that it could set a precedent, putting us on a slippery slope that would lead to things like germ-line engineering. Well, OK, then what's wrong with germ-line engineering? I myself have doubts about it—a primary one being the sharp-genetic-stratification scenario outlined above. But, since I'm a utilitarian, my doubts boil down to fears that it could lead in various ways to unhappiness—and pretty much everyone, even non-utilitarians, accepts the premise that happiness, all other things being equal, is better than unhappiness. Your moral qualms seem more elusive. On the one hand, you're not appealing directly to religious authority. But you are appealing to moral absolutes that go beyond the minimal utilitarian assertion that happiness is a moral good. Can you spell those bedrock values out? In other words, which of your core moral intuitions do we have to share if we are to agree with you that there is something wrong in principle with parents choosing to have offspring who are "better than natural"—instinctively less prone to hatred and intolerance and violence than the typical human?