Business is booming for Robin DiAngelo, a retired sociologist and the author of White Fragility: Why It’s So Hard for White People to Talk about Racism. Since resigning from Westfield State University three years ago, DiAngelo has become a full-time “writer and presenter.” What she writes about is the pathological inability of white people to understand their passive complicity in America’s “white supremacist culture,” and whom she presents it to is white people looking for lessons in how to overcome it. “Now breathe,” she instructs her readers. “I am not saying that you are immoral. If you can remain open...