If there is no god, it is still the height or hubris to see "survival of the fittest" and take upon yourself the judgment of who is fit. If you believe that natural selection is a self-correcting mechanism, why interfere? Things will shake out as they should. As they have to. For people who believe in evolution, as I do, the only sane solution is to leave it the hell alone.
Eugenics has always been rife with assumptions -- about the "lower races" with their vices and weaknesses, and built around how we can make more of us and fewer of them. Eugenics is not a problem with evolution. It's a problem with people who think they can game the system.
“If you believe that natural selection is a self-correcting mechanism, why interfere? Things will shake out as they should. As they have to. For people who believe in evolution, as I do, the only sane solution is to leave it the hell alone.”
The problem with this is that you are making a moral judgement - that “interfering” with natural selection is “wrong”. Why is it wrong?
Even if it could be demonstrated that Darwin was against eugenics, if there is no God, then so what if he was against it? Without God there are no moral absolutes - only personal preferences created by our own whims.
As to the original question, what does Darwin teach that would prohibit the practice of eugenics on human beings?
Is it simply because he says “natural” selection? Does that phrase eradicate the very idea of science utilizing this “natural” process themselves?
My point is that Darwinian theory lends itself to eugenics while violence and atrocities committed in the name of Jesus have no basis of support from anything He taught (or of any New Testament writers for that matter).