I think we can have the idea of improving genetics in a high-tech way without all of the Nazi baggage like Social Darwinism, racism, etc. that comes with 'eugenics'.
The thing is, "Social Darwinism" et al demonstrate that the instant we even thought we might have this power, the Powers That Be instantly started doing things with it that other people found reprehensible, including (using it to justify) wholesale slaughter.
If you think people have morally become greatly advanced in the past 100 years, then this might not bother you. But you would also be operating in a regime of aggressively blind faith, because the evidence for that claim is exactly inverted.
If, on the other hand, you don't believe that, you might spare some thought for the last time this was popular.
And, I mean this entirely seriously, you should seriously take a moment to wonder whether you will be deemed undesirable in any exciting new order of these sorts of things. There is ABSOLUTELY NO NATURAL LAW that your ideological allies will be the ones who get this power. Not even being part of the dominant ideology today shields you from being on the dominant ideology's shit list 20 years from now. To a great extent, it is rational to make sure nobody gets these ideas because you, personally, ilaksh (and jerf) may well discover that you are on the receiving end of the 21st century nastiness. (How many of the 20th century's victims were individually actually on the government's side, right up until they were being slaughtered?)
Some country somewhere is going to legalize this. Their citizens will have IQs several standard deviations higher than ours. Dr. Steven Hsu seems to think IQs far higher than 180 (before renorming) are very possible. All countries will be forced to allow (or even subsidize) genetic intelligence augmentation. This is the nature of the incentives that will develop. We have very little choice in the matter. Any country with reservations will become a cognitive backwater, whose intellectuals will be routinely out-performed by grade-school children.
From my perspective, it is tragic that some children are born with brains that cannot understand basic arithmetic. It is equally tragic that most are born with brains that cannot understand advanced physics. This technology will allow us to remedy a good portion of our ignorance. It should be embraced. Iodizing salt increased average IQ in many regions by a standard deviation. Reducing lead pollution about 8 more on top of this. Were these great evils? Why is removing deleterious mutations?
Or we accept that the net good that will happen is so great that it's okay even for my ideological enemies to have this power, just so long as SOMEONE does. Lots of people would admit this of space travel. Eugenics is closer to the border line.
You're begging the question. We have no great assurance that the net will be good, for any given definition of good, including yours, and certainly not for all of them simultaneously.
