  Over the course of his career, Du Bois’s social philosophy comprised contributions to social ontology, social theory, the philosophy of the human and social sciences, and the diagnosis of social  problems.[1] His analysis of the nature of a social problem and, specifically, his diagnosis of the Negro problem; his social constructionist accounts of race and racial differences; his ongoing reflection on the methods, purposes, and sometimes moral significance of social inquiry; and his elaboration of the claim that the concept of race, operating as a mechanism of power, structures relations of social domination, all played a critical role in what he ultimately came to call his “evolving program for Negro freedom” (1944, 31). The present section bears on Du Bois’s analysis of the Negro problem and his contributions to the philosophy of race. Section 3, below, focuses on his contributions to the philosophy of the social sciences.