Those who are in ideology believe themselves by definition outside ideology: one of the effects of ideology is the practical denegation of the ideolo… - Louis Althusser

But someone is bound to question ... by what right I regard as Ideological State Apparatuses, institutions which for the most part do not possess public status, but are quite simply private institutions. As a conscious Marxist, Gramsci already forestalled this objection in one sentence. The distinction between the public and the private is a distinction internal to bourgeois law, and valid in the (subordinate) domains in which bourgeois law exercises its ‘authority’. The domain of the State escapes it because the latter is ‘above the law’: the State, which is the State of the ruling class, is neither public nor private; on the contrary, it is the precondition for any distinction between public and private. The same thing can be said from the starting-point of our State Ideological Apparatuses. It is unimportant whether the institutions in which they are realized are ‘public’ or ‘private’. What matters is how they function.

Like every 'intellectual', a philosophy teacher is a petty bourgeois. When he opens his mouth, it is petty-bourgeois ideology that speaks: its resources and ruses are infinite.

Class instinct is subjective and spontaneous. ... To arrive at proletarian class positions, the class instinct of proletarians only needs to be educated; the class instinct of the petty bourgeoisie, and hence of intellectuals, has, on the contrary, to be revolutionized.