Talking about racism won't end these problems. Our cities are saturated with militarized law enforcement officers. An extraordinarily high number of American civilians are killed by police each year. The U.S. prison population is the largest in the world. And we are only beginning to understand why. In recent years, scholars such as Naomi Murakawa and Marie Gottschalk and activists in the Black Lives Matter movement have broken from the civil rights generation's obeisance to the Democratic Party, and from the left's reflexive assumption that "law and order" Republicans are exclusively to...