The Current Discussion: The slaughter last week of Kikuyus and Luos in Kenya reminded us that this is a world of tribes. How should wise governments deal with the reality of tribal loyalties and tribal violence?

A lot of what appears on PostGlobal is critical of the United States, and quite properly. But on this question of tribal violence, I think the U.S. of A. actually has something to teach the world. America's gift in the 21st century is that we have learned how to make a diverse, multicultural society work.

That wasn't always the case. It took America many decades to grapple with the legacy of slavery, which the sociologist Gunnar Myrdal called our "original sin." But nobody who knows America can deny that we are a different country today in terms of racial relations than we were 40 years ago. This was a painful process of change, sometimes marked by violence. But if you want to see the harvest of good that we have reaped, just watch Barack Obama on the campaign trail. If an African-American can win the Democratic primary in the white-bread state of Iowa, then we've come a long way.

America's ability to absorb Latino immigrants is being tested now, because of the huge influx of illegal immigrants. But still, this is basically a success story. Hispanic Americans are an increasingly prosperous and dynamic community.

This is America's gift: We bring together hard-working, talented people from around the world. We give them a chance to compete and prosper. Our multi-cultural society manages the tricky balance of assimilating people to certain common values, while at the same time allowing them to be faithful to their ethnic roots. We do a lot of things wrong, but this is a case where America has it right.