altruism, concept in philosophy and psychology that holds that the interests of others, rather than of the self, can motivate an individual. The term was invented in the 19th cent. by the French philosopher Auguste Comte, who devised it as the opposite of egoism. Herbert Spencer and John Stuart Mill, English contemporaries of Comte, accepted the worth of altruism but argued that the true moral aim should be the welfare of society, rather than that of individuals.