President Barack Obama eloquently described the agony experienced among African-Americans from the slaying of Trayvon Martin. He called for a more thoughtful “conversation” on race, convened not by politicians, but among families, in churches and workplaces. He suggested modest steps to provide greater training on racial profiling with police, greater efforts to figure out how to do a “better job helping young African-American men feel that they’re a full part of this society and that they’ve got pathways and avenues to succeed.” The president’s courageous comments merit praise and consideration. But we’ve had a long conversation about race in America. …