U.S. sociologist and economist, prolific publicist of Social Darwinism.

Like the British philosopher Herbert Spencer, Sumner, who taught at Yale from 1872 to 1909, expounded in many essays his firm belief in laissez-faire, individual liberty, and the innate inequalities among men. He viewed competition for property and social status as resulting in a beneficent elimination of the ill adapted and the preservation of racial soundness and cultural vigour. For him the middle-class Protestant ethic of hard work, thrift, and sobriety was conducive to wholesome family life and sound public morality. Foreseeing the drift toward the welfare state, but considering poverty the natural result of inherent inferiorities, he opposed all reform proposals that smacked of paternalism because they would impose excessive economic burdens on the middle class, his “forgotten man.” In his best known work, Folkways (1907), he stated that customs and morals originate in instinctive responses to the stimuli of hunger, sex, vanity, and fear. He emphasized the irrationality of folk customs and their resistance to reform. Sumner's notes became the basis of The Science of Society, 4 vol. (1927–28), edited by Albert G. Keller.