Sumner, William Graham (1840-1910), was an American sociologist known for his study of popular traditions and customs. Social groups unconsciously develop ways of doing things that are handed down from generation to generation. Such customs, which Sumner called folkways, include rules of etiquette and standards of personal grooming. Sumner used the Latin word mores for folkways that reflect ideas of morality, and that a society considers vital to its welfare. Mores include remaining loyal to one’s country and preventing close relatives from intermarrying.
Sumner pointed out that folkways vary from society to society. Each society believes its own are the best and most natural. He called this attitude ethnocentrism.
Sumner was born in Paterson, N.J. He taught at Yale University for many years. Sumner introduced the ideas of folkways, mores, and ethnocentrism in his book Folkways (1906).