  In “The Study of the Negro Problems,” Du Bois predicates his analysis of Negro problems on his analysis of social problems as such; in another early essay, “The Conservation of Races” (1897a), he similarly predicates his answer to the question, “What is a Negro?” on an answer to a more fundamental question, “What is a race?” Du Bois turns to the human sciences to say what a race is, but also to account for the existence of spiritually distinct races. Du Bois’s historical-sociological definition of race overlaps his historical-sociological explanation of the existence of spiritually distinct races. To put the point more precisely, and in an idiom that is familiar to contemporary philosophers, Du Bois holds that the same sorts of historical and social factors construct race both constitutively and  causally.[7]