The July 16 arrest of Harvard professor Henry Louis Gates at his own home in Cambridge, Mass., and the resulting media commotion tell us that race in America is not a settled issue.

President Barack Obama is referred to as "African-American," but he is half-white. Who benefits from this labeling? African-Americans should, as they now have a role model who looks more African than any president so far. But it was the media that started it. Were they looking to stir up racial controversy in the name of entertainment?

Anthropologists tell us that race is a phony concept. Geneticists say that humans share such an enormous proportion of the genome that it is trivial to talk about differences. Historians tell us that "white" was a product of pre-Constitution wrangling to drum up political support for America's rich white (male) landowners. It seemed pretty clear that the actual interests of poor whites were more aligned with those of black slaves than with those of rich whites.

Then there's the Rev. Jeremiah Wright. If you happened to hear his speech to the Detroit NAACP convention on April 27, 2008, you heard him hammer on a revolutionary, inflammatory, divisive message: Different is not deficient. "Tell it to your neighbor," he shouted, "Different is not deficient!" If you only heard the pundits talk about the speech, you might think he had mortally insulted all white people and crippled Barack Obama's campaign for his own selfish purposes. And that was just CNN!

What he said was that no one should believe that African-Americans are not "as good as" others, or are worthy of our fear and loathing. What he said was that people who are different from the majority are still people.

He could have used Dr. Seuss's story about the sneetches on beaches - some had "stars on thars," some didn't. As time rolled on, first those with stars were dominant, then those without. Enterprising entrepreneurs, meanwhile, made fortunes tattooing and then removing stars.

Anyone who has ever attended a predominantly black Christian church would not be startled or offended by the Rev. Wright. Nor should it be controversial that African-Americans have suffered greatly, that pastors would empathize with and encourage their congregations, or that prominent black professionals would be outraged at being accused of breaking into their own homes.

Prejudice goes in all directions, alas. Recently the Rev. Wright was heard to comment about "them Jews" who wouldn't let him talk with the president, and he spoke of "genocide" on the West Bank - harsh language indeed for Jews whose families were wiped out in the Nazi genocide. Nevertheless, it is true that Palestinians are suffering and dying at the hands of Israel; and yes, the reverse is also true. Violent hatred on one side does not justify it on another side. The Rev. Wright gets it about the West Bank; he doesn't get it about the Jews.

In Detroit, the Rev. Wright had them rolling in the aisles, and me too, when he announced the biggest difference between white and black people. Whites, it seems, clap in time on the first and third beats: "ON-ward CHRIS-tian SOL-diers …," but blacks clap in time on the second and fourth beats: "on-WARD Chris-TIAN sol-(CLAP)-diers (CLAP)…." Listen to the music with roots in black America - gospel, blues, rock 'n' roll, rap, hip-hop - and you'll know he nailed it.

Wright is clearly out of step with America's desire for self-deception (we're not racist; Palestinians aren't suffering; black people have no reason to feel like victims). And he is definitely out of line with the biased, defamatory, even nasty language he too often uses.

But extremists can articulate truths that no one wants to acknowledge, even if they do so in language that the majority cannot accept. From studies of social movements, we learn that extremist voices typically push the vast middle out of their comfort zones, toward acceptance of more moderate voices for beneficial change. That isn't so bad.