[yummyfajitas]

I was under the impression that communism was centered around the notion that people are all equal and highly malleable, not that there were intrinsic and immutable differences between human groups.

But assuming you are actually referring to nationalists (who probably rank #2 on the list of "worst things humans have done to each other"), I'll just quote a blog post Bryan Caplan wrote today:

We've learned so much from human genetic research. But when I read Fisher, I understand why the subject terrifies so many people. Hereditarianism combined with inane, half-baked moral philosophy does indeed logically imply Nazi-style homicidal mania. But don't blame the facts of human genetics. Blame the inane, half-baked moral philosophy.

http://econlog.econlib.org/archives/2012/01/the_demented_pa....

[MartinCron]

Wasn't referring to nationalists specifically. I was thinking of the broad ranger range of things like slavery, genocide, segregation, apartheid, etc.

If you think that communism is worse, that's fine by me. It doesn't change the fact that history is littered with cautionary examples of group-based determinism gone terribly wrong. It's naive to pretend otherwise.

[yummyfajitas]

History is also littered with cautionary examples of [belief in] equality and malleability gone terribly wrong.

"Meaningful variations between groups" does not logically imply that concentration camps are good policy, just as a belief in equality does not imply that gulags are.

Supposing that Jews are only half as smart as Aryans, it doesn't imply that they should be killed. Similarly, if I'm twice as smart as my maid, it doesn't follow that I should murder her. In both cases, you need some intrinsic moral belief that killing is acceptable - and that's where the real problem lies.

Also, need I point out that you are employing the logical fallacy of "appeal to consequences"?

[MartinCron]

I'm not even sure what the argument is here. I gave an honest and legitimate reply to the question "Why is it so hard to imagine that maybe there are meaningful group variations within the human species?"

I'm not saying it should be so hard. If we had a greater understanding of differences, that would probably be great. But it is hard, and it helps to be honest about that.