The problem is not exclusive to this issue or this conference. Similar criticisms can be made of the gun control movement, in which black people, who are the most likely to be affected by gun violence, generally have supporting roles as grieving parents but rarely take center stage as advocates for new legislation. Former New York mayor Michael Bloomberg’s decision to plow millions into the cause is welcome. But however large a check Bloomberg writes, the poster boy for stop-and-frisk is not going to get much traction in the urban areas where gun violence is most prevalent.

Nor is this a new problem. It’s a longstanding, endemic and entrenched feature of what purports to be the American left and the causes with which it identifies. It is difficult to imagine a progressive American movement that does not have the interests of minorities and the poor at its heart—whom else would it exist for? As Karl Marx noted in Capital: “Labor cannot emancipate itself in the white skin where in the black it is branded.” And yet the physical presence of those groups in the spaces created by the “left” all too often appear as an afterthought, if indeed they appear at all.

“However rebellious children may be, they have their parents’ genes,” wrote Andrew Kopkind in 1968. “American radicals are Americans. They cannot easily cross class lines to organize groups above or below their own station. They are caught in the same status traps as everyone else, even if they react self-consciously.”

This ought to be a civil conversation among friends. Those born white and wealthy should not be slammed for developing a social conscience, becoming activists and trying to make the world a better place. But neither should the nature of their involvement be above critique. When their aim is to fight alongside low-income people and people of color as brothers and sisters, real advances are possible. But when they look down on these people as younger stepbrothers and stepsisters to be brought along for the ride, precious few gains are made.