After the war, Selznick returned to Columbia, where he earned a Ph.D. in sociology in 1947. Two years later, he published “TVA and the Grass Roots,” a renowned sociological study of the Tennessee Valley Authority. In this work, Selznick found that a formal organization “is an adaptive social structure” facing problems independent of its creation. He noted that such organizations are shaped by forces separate from their stated structure and goals, and that individuals in the organization function as a “whole” with actions and alliances separate from the organization.