The concept of ideology is often associated with the work of Friedrich Engels (1820–1895) and Karl Marx (1818–1883). In general, Marxists approach cultural forms as emerging from specific historical situations that serve particular socioeconomic interests and that carry out important social functions. For Marx and Engels, the cultural ideas of an epoch serve the interests of the ruling class by providing ideologies that legitimate class domination. "Ideology" is a critical term used in Marxist analysis that describes how the dominant ideas of a ruling class promote the interests of that class and help mask oppression and injustices. Marx and Engels argued that during the feudal period, piety, honor, valor, and military chivalry were the ruling ideas of the reigning aristocratic classes. During the capitalist era, values of individualism, profit, competition, and the market became the dominant ideology of the new bourgeois class, which was then consolidating its class power. Because ideologies appear natural and common-sensical, they often are invisible and elude criticism.
Marx and Engels began their critique of ideology by attempting to show how ruling ideas reproduce dominant societal interests and relations and serve to naturalize, idealize, and legitimate the existing society, its institutions, and its values. In a competitive and atomistic capitalist society, it appears natural to assert that human beings are primarily self-interested and competitive, just as in a communist society; it seems natural to assert that people are cooperative by nature. In fact, human beings and societies are extremely complex and contradictory. Ideology smoothes over contradictions, conflicts, and negative features, idealizing human or social traits like individuality and competition, which are then elevated into governing concepts and values.