Two tragedies are apparent in the Trayvon Martin case. The first is obvious: A teenager—unarmed and committing no crime—was shot dead. Dressed in a "hoodie," a costume of menace, he crossed paths with a man on the hunt for precisely such clichés of menace. Added to this—and here is the rub—was the fact of his dark skin.

Maybe it was more the hood than the dark skin, but who could argue that the skin did not enhance the menace of the hood at night and in the eyes of someone watching...