WASHINGTON—Almost any form of political incorrectness has a seductive quality about it, even if what is said or written is downright outrageous. But when it actually sheds light on some important truths, and when the person uttering them has a wide audience, it takes on a subversive significance. Such was the case of the speech on race given by Barack Obama in Philadelphia on March 18.

I eulogize that speech with the proviso that I don’t share many of Obama’s ideas on the role of government. Like so many liberals, he fails to see the contradiction between denouncing the government’s intrusion into one’s body, one’s bedroom or one’s conscience and advocating approaches to social ills that entail spending—and therefore taxing—more of the people’s money and limiting their free choice.

In any case, the speech did more than provide historical context and nuance—it went to the heart of racial tensions in America.

Political correctness mandates that we talk about African-Americans purely as victims of white society. Yet there are internal reasons that also explain the relative failure of many African-Americans to prosper in recent decades. They have to do with the politics of victimhood and of transferring the responsibility for one’s condition to forces beyond one’s control. This kind of politics fails to take into account the achievements of African-Americans in business, the arts, sports and other pursuits.

The fact that—as Obama stated in his speech while criticizing the Rev. Jeremiah Wright’s outdated vision—many blacks have made progress in the United States attests to the opportunities for social mobility that contemporary institutions offer to the children and grandchildren of slavery.

Political correctness mandates that self-styled spokesmen for minorities don’t trumpet “white” values because by doing so, they betray their people—the reason why much abuse has been hurled at Bill Cosby for criticizing the social mores of the ghetto. Obama cut not only through the racial but also the ideological divide when he praised the value of “self-help” and referred to it as “conservative”—meaning he had no qualm in finding value in what is a cornerstone of the social vision espoused by the adversaries of liberalism.

Political correctness mandates that we do not acknowledge fear of one another because violence feeds on that primeval instinct. But suppressing fear in speech, which is what political correctness does, is not the same as overcoming it—it merely makes sure, as Obama put it, that “that anger (is not) expressed in public, in front of white co-workers or white friends. But it does find voice in the barbershop or the beauty shop or around the kitchen table.”

Some have taken Obama to task for equating different forms of racial mistrust in the most personal segment of his speech. Referring to the Wright, Obama said, “I can no more disown him than I can my white grandmother—a woman who helped raise me, a woman who sacrificed again and again for me...but a woman who once confessed her fear of black men who passed by her on the street.”

As Christopher Caldwell, a senior editor at The Weekly Standard, not exactly a liberal publication, recently wrote in the Financial Times, “This is actually where the subtlety of Mr. Obama’s argument lies.” The foundation of his policies on race, he goes on to say, has been that black progress means, in Obama’s own words, “binding our particular grievances—for better health care, and better schools, and better jobs—to the larger aspirations of all Americans.”

The speech induces us to believe that this can only happen on two conditions—that blacks stop seeing themselves as a defensive enclave within the larger American society and that whites stop masking their yet unresolved prejudices against blacks in the euphemisms of political correctness.

I happen to think that only the blending and transformative powers of a free society—politically, economically and morally free—will dissolve fear and mutual grievances into something approaching a colorblind environment. That means, in my view, that some of the protectionist and interventionist policies that Obama advocates will not achieve the end he eloquently defined. But the mere fact that a man with a real shot at the presidency was willing to address these truths turned this presidential campaign, for one brief moment, into something very meaningful.

His personal narrative and oral gifts made him uniquely positioned to give that speech. It is commendable that, having so much to lose, he chose to do so.