Eliezer S. Yudkowsky, <firstname.lastname@example.org>, writes:
> Let's ask the question this way: Most people would say that we don't have the
> right to modify a genome, or perform neurosurgery, to increase intelligence.
> Suppose a mutation arises naturally containing that modification. Should he
> be prevented from having children? Can his genes be inserted artificially?
> Can an improved version be engineered de novo?
In this case there is an important extra piece of information: a subject who already has experienced some form of alteration or enhancement, and likes it. He wants to pass it on to his offspring, which will tend to happen naturally if it is genetically based, and could be arranged to happen artificially in any case.
Perhaps we can generalize and say that modifications of unborn children are OK as long as most people who had received such modifications were happy about it. This is not a perfect generalization, in that there might be a situation where someone liked a trait and wanted his kids to have it, but most people with that trait hated it. In that case we might question the wisdom of passing it on.
This does not help much when we propose to impose a modification for the first time, since there are no others we can poll who have the mod. In that case we might adopt a policy of gradualism, combined with consensual physical modifications. Let's see a population of people satisfied to have their legs surgically removed before we decide to have children born without them.
Gradualism will be more difficult in some cases, like turning feet into hands, or John Clark's human bags of hydrogen gas living on Jupiter (giving new meaning to "fire in the belly"?). Even then it may be possible to make the changes incremental by using some imagination.
BTW I always try to split this kind of question up into two parts. The first is, is it wise and proper to make modifications to your unborn children in this way? In other words, if someone came to you and asked your advice about whether they should do it, would you say that it is a good idea. We approach the question on an individual level and try to decide what approaches would be best, from a moral and ethical perspective.
Once that is done, you can pull back and look at it from society's point of view. Should coercion be used to enforce this morality? Think of murder, which most people agree is wrong on a personal level, and they are so sure of their feelings that they feel comfortable enforcing this prohibition on everyone.
It seems to me that cases where the proper path is fuzzy or unclear at the individual level should be the last ones where society decides to employ coercion. If I don't know what is the right thing to do, I certainly shouldn't be telling you what to do. So it is important to analyze the individual case carefully in order to both decide what is the ethically proper course, and also how much certainty we can have about it.