The past is another country
A while back, on my old blog, I triggered a lot of anger by pointing out that if you applied the same standards to Victorian America as the "Arab culture is rotten to the core" folks do to the Middle East, the revered pioneer ancestors who built America suddenly turn into . . . a bunch of sick monsters whose culture was rotten to the core.
Now Bryan Caplan is poking the same hornet's nest:
Critics of multi-culturalism often mock its proponents for (a) cultural relativism and (b) disrepecting Columbus. The problem, as I've explained before, is that Columbus was a pioneer of slavery and barbarism. The only way to excuse his behavior is to say "Oh, you can't judge Columbus by our standards. In those days, people thought that slavery was OK. Everyone was doing it."
If that excuse makes sense to you, you're a cultural relativist. Change your heroes, or change your meta-ethics!
This cuts both ways, of course: you cannot, as some leftists do, simultaneously argue that pre-1960s Western culture was rotten with sexism, racism, etc., and also that you cannot judge people living in non-Western cultures by our own standards. If the equality of all men and women really is such a universal truth that it is reasonable to demand that Victorians should have divined it, then it is also reasonable to expect the tribes of Papua New Guinea have done the same.
Myself, I'm an unabashed cultural relativist. I don't think it's reasonable to hold either our ancestors, or our brethren abroad, to our cultural standards. But I think its especially unreasonable to apply those standards only to select groups of people I already have reason to dislike.