I have no problem with attempts to address serious externalities that arise from otherwise harmless personal activities. But if government does not bear a heavy burden of proof when justifying such intrusions into our lives, it can employ vague arguments about social harm to take away our basic freedoms. Francis Fukuyama would push us towards just such intrusions by erecting a powerful regulatory structure charged with ensuring the ethical and social desirability of future technologies.

Fukuyama is so suspicious of change in general and new technology in particular that he won't even acknowledge the desirability of allowing people to use safe and beneficial interventions that would almost certainly improve their lives. He will only admit that if a technology is "safe, cheap, effective, and highly desirable," government probably [my emphasis] should not try to stop it." If he won't even embrace technologies that meet this high threshold, he would never allow the far more problematic possibilities of the real world. But facing such possibilities is precisely what has improved our health and raised our standard of living so greatly during the past century.

Fukuyama speaks of safety, but his reluctance about even safe and highly desirable technologies suggests that his major concern is neither safety nor aberrant misuse. Moreover, he admits that these dangers are well covered by existing agencies and institutions. He makes his primary focus explicit in his book when he complains that the FDA is charged only with establishing "safety and efficacy," whereas we need institutions that can look at ethical consequences.

For the most part, Fukuyama is vague when it comes to precisely what we should prevent. This may be good strategy, because notions of safety, caution, and minimized externalities are so appealing. However, it is deceptive because it is in the details that the rubber meets the road.

In fairness, he is specific about banning human cloning, which in today's climate is about as risky as coming out for motherhood. However, his reasoning here is faulty. To liken a blanket ban on reproductive cloning to a ban on incest is not even fathomable if one considers the cloning of a deceased child or someone other than the parent. But as I said, cloning is a sideshow.

A more interesting situation is sex selection. I argued that in the U.S, such selection--which can be done by sorting sperm so that no embryos are destroyed--is innocuous. Sex selection does not harm children; indeed, it likely benefits them when a child of the "wrong" sex would seriously disappoint his or her parents. Fukuyama brings up the imbalance in sex ratios in China, but this does not justify regulating the practice here, where such imbalances do not arise from the practice. Moreover, the problem in China is hardly an argument for government regulation, since sex selection there has long been illegal. Indeed, government regulation in China - namely, its one-child policy - exacerbates the problem of gender balance by pushing parents who want a boy toward aborting a girl, since they can't try again. Fukuyama opposes sex selection here and has proposed the formation of a review board like the one in Britain that has barred this procedure, but does he have anything better to offer than a fear that the practice would be a step down a slippery slope? If he sees a serious externality to sex selection in the U.S., it would be worth hearing.

In response to my comments about the obvious appeal and benefit of future anti-aging medications, Fukuyama points out that "negative externalities can arise from individual choices to prolong life at the cost of a lower level of cognitive and physical functioning." This is true, but it is a frightening basis for legislation (as opposed to decisions regarding government-funding). I shudder to think about regulatory boards tasked with balancing the additional years that an individual seeks against the social cost of those years. To see the peril, we need only apply Fukuyama's logic to medicine generally.

If he does not want to allow interventions to slow the onset of aging and bring longer lives of relative health (though presumably not matching the vitality of youth itself), then why not block all treatments for the aged and debilitated? Their extra years are a net cost, and withholding medical treatment for those over 65 would work wonders on our ailing Social Security system. It isn't much of a step to go even further and block medical interventions that save accident victims who suffer crippling injuries.

Fukuyama no doubt feels that a sharp line between therapy and enhancement will avoid such perversions, but this distinction does not stand up to scrutiny. This line will increasingly blur in the years ahead. Anti-aging interventions, for example, fall in a large realm that is best labeled therapeutic enhancement. If we could gain an extra decade by strengthening our immune system or our anti-oxidation and cellular repair mechanisms, this would clearly be a human "enhancement." But it would also be a "preventive therapy," because it would delay cardiovascular disease, senile dementia, cancer, and other illnesses of aging, which we spend billions trying to treat.

Banning enhancement from sports competitions can obviously be justified as a violation of the agreed rules of the game. But neither Fukuyama nor our democratic political institutions have a recognized right to set the rules of life. Outlawing a whole realm of benefits that are not injuring others is not just impractical, it is tyranny. Enhancement is not wrong, and when such possibilities become safe and reliable, large numbers of people will seek them. Fukuyama is right about the ambiguities of "improvement," but I have not suggested some grandiose government project that seeks human perfection. I have spoken only of freely made parental choices, and I argue that such choices are likely to lead towards great diversity.

I do not argue that parents need no oversight in the use of advanced technology for the conception of children, just that it should be minimal, should address real rather than imagined problems, and should be concerned with the child's safety rather than social order or the personhood of embryos. When it comes to children, I trust the judgment of individual parents more than that of political or judicial panels. Most parents are deeply concerned about the welfare of their own children, whereas such panels are composed of individuals who are more oriented towards larger social and philosophical concerns than the well-being of particular individuals.