It’s time to talk about what it means to be white in the United States. That’s what I was trying to do Saturday afternoon at the Politics and Prose bookstore in Northwest Washington when I was interrupted by a group of white nationalists. Ironically, the protesters’ chant — “This land is our land” — served only to reinforce my point. For too long, many white Americans have avoided this conversation, and we’ve done so for a reason: We don’t have to see the color white. Race scholars often argue that white privilege broadly means not needing to reflect on whiteness....