> So when a white person gets a high-paying job, it's because of history of slavery. If a black person gets a high-paying job, it's because they worked hard. Did I get that right?

Not quite. I said "led to", not "because", and everything that happens today was "led to" by history, including a black person getting a high-paying job. Remember this was all in response to this rather amazing comment:

> My ancestors were thousands of miles away from US territory when slavery happened ... and yet you're saying I'm supposed to pay the price for your crimes just because of my skin color.

You're using "my" and "we" to mean "me and my particular ancestors" and "you and your ancestors", whereas the person you were replying to was very clearly using "we" to mean "the history of all of humanity". The latter acknowledges reality as it is right now and the events leading up to it, and the former relies on some magical inheritance of responsibilities depending on your blood ancestors.

> So Genghis Khan has nothing to do with that. But slavery has everything to do with that.

Again you're ignoring the point. Both of these events led to the world as it is today, and neither of us is more responsible for them than the other. Your ancestors, my ancestors: that has nothing to do with it. And you're the one who started out assigning blame and "why should I pay!?" based on whose ancestors are whose. Affirmative action proponents are not doing that. They're looking at the situation as it currently exists right now and trying to make it better. We can debate whether their particular approach works or not, but we can not say "it's not my problem because of who my ancestors are".

(That's not even mentioning the fact that Genghis Khan died in 1227 and there are people alive today whose grandparents were born slaves.)

> To me "optimal" is the minimum amount of effort that leads to maximum results. E.g. if you get enough resumes by posting a job on your website you don't need to put extra effort to find more candidates.

So your definition of "optimal" is wrong, in any reasonably complex situation. What if your job posting was written poorly and all your applicants thought the job was something a little different? They could literally all be mis-qualified for the job, and you'd never have the opportunity to realize there are much better candidates out there. That's an example of "systemic bias" that prevents optimal outcomes. If you suddenly realize your job posting was crap and your candidate pool is sub-par because of it, you should take some affirmative actions to fix it, rather than spend "the minimum amount of effort."

Can we think of any other systemic biases like that, that prevent optimal outcomes? Any at all? Like, oh, I don't know, race discrimination?

> 1. How should countries with homogenous skin color deal with history of slavery?

By learning about it and understanding its effects on their society today? The same way I'm suggesting the U.S. does?

> 2. Should we exclude Nigerian Americans from DIE / affirmative action policies, because they are doing better than average American?

I don't agree with all the ways DIE / affirmative action are practiced today. I agree with many of the criticisms levied against it in this comment thread. Many other criticisms sound like they're rooted in the fundamental idea of "racism is natural/historical/OK and I'm racist for saying so, you're racist for disagreeing". I'd rather have DIE / affirmative action as we have right now than nothing, and certainly than whatever world you imagine where we (humanity) can essentially bully another group of humans for centuries, and then when we realize that actually doesn't lead to optimal outcomes in society, we shove them back down again anyway in some sunk-cost fallacy in order to avoid those nasty uncomfortable feelings of shame, regret, and blame (which have nothing to do with it anyway).