The election of Barack Obama was supposed to be the bright new dawn of a post-racial America. His swearing in on the steps of Washington's Capitol building seemed to represent a historical watershed, a full stop at the end of a chapter in United States history that included segregation and slavery. So what has gone wrong with America since that frigid January day? Turn on the news now and we are assailed with reports of disgracefully racist placards being carried at anti-Obama rallies nominally billed as opposition to health-care reform. A virulent campaign by the so-called "Birthers" is being waged,...