Many Americans might not know the more polemical side of race writing in our history. The canon of African-American literature is well established. Zora Neale Hurston, Richard Wright, James Baldwin are familiar figures. Far less so is Samuel Morton (champion of the obsolete theory of polygenesis) or Thomas Dixon (author of novels romanticizing Klan violence). It is tempting to think that the influence of those dusty polemics ebbed as the dust accumulated. But their legacy persists, freshly shaping much of our racial discourse.