In Marxist philosophy, the term dominant ideology denotes the attitudes, beliefs, values, and morals shared by the majority of the people in a given society.
In Book 3 (414e–15c) of The Republic, Plato presents the Noble Lie (gennaion pseudos, γενναῖον ψεῦδος) in a fictional tale, wherein Socrates establishes and justifies the origin of the socially stratified society: ... the earth, as being their mother, delivered them, and now, as if their land were their mother and their nurse, they ought to take thought for her and defend her against any attack, and regard the other citizens as their brothers and children of the self-same earth...
While all of you, in the city, are brothers, we will say in our tale, yet god, in fashioning those of you who are fitted to hold rule, mingled gold in their generation, for which reason they are the most precious—but in the helpers, silver, and iron and brass in the farmers and other craftsmen.
So that the first and chief injunction that the god lays upon the rulers is that of nothing else are they to be such careful guardians, and so intently observant as of the intermixture of these metals in the souls of their offspring, and if sons are born to them with an infusion of brass or iron they shall by no means give way to pity in their treatment of them, but shall assign to each the status due to his nature and thrust them out among the artisans or the farmers.
Based upon their experiences of societal life, the men and women of each social class (upper, middle, lower) construct their intellectual understanding of the society, and, because their societal experiences are primarily of capitalist social relations, the shared (dominant) ideology tends to reflect the norms of a capitalist society.
In other words, Marxist critiques of the dominant ideology of capitalism are not normally crude rejections of their content, but rather of their limiting, capitalist form.