Born Oct. 30, 1840, in Pa-terson, N.J.; died Apr. 12, 1910, in Englewood, N.J. American sociologist, economist, and publicist. Representative of social Darwinism. Professor of political and social science at Yale University.

Sumner, whose ideas developed primarily under the influence of H. Spencer, defended two main principles: the universality of natural selection, which he interpreted to include the idea that selection and the struggle for existence are natural in society, and the concept of the automatic, unchanging character of social evolution. Taking these principles as his point of departure, Sumner regarded social inequality as a natural and essential condition for the existence of civilization, advocated laissez-faire in social development, and opposed government regulation and attempts at social reform and especially revolution. His views expressed the interests of the middle strata of the American bourgeoisie, who, confronted by the intensification of state-monopoly tendencies, were demanding favorable conditions for free competition.

In Folkways (1906), which is based on an analysis of extensive ethnographic sources, Sumner developed the concepts of the “in-group,” the “out-group,” and “ethnocentrism” in “primitive” societies and the initial stages of human history. He characterized relations within the in-group as cohesive and relations between the in-group and the out-group as hostile. According to Sumner, hostility is associated with ethnocentrism, or man’s proclivity for appraising the environment through the prism of the cultural notions of his social (ethnic) group. Folkways is important in the history of social psychology and ethnopsychology not for its author’s social Darwinist principles but for its analysis of normative aspects of social life, certain features of customs, and other phenomena.