Class instinct is subjective and spontaneous. ... To arrive at proletarian class positions, the class instinct of proletarians only needs to be educa… - Louis Althusser

For you and for me, the category of the subject is a primary ‘obviousness’ (obviousnesses are always primary): it is clear that you and I are subjects (free, ethical, etc.). Like all obviousnesses, including those that make a word ‘name a thing’ or ‘have a meaning’ (therefore including the obviousness of the ‘transparency’ of language), the ‘obviousness’ that you and I are subjects – and that that does not cause any problems – is an ideological effect, the elementary ideological effect. It is indeed a peculiarity of ideology that it imposes (without appearing to do so, since these are ‘obviousnesses’) obviousnesses as obviousnesses.

All ideology hails or interpellates concrete individuals as concrete subjects, by the functioning of the category of the subject. ... ideology ‘acts’ or ‘functions’ in such a way that it ‘recruits’ subjects among the individuals (it recruits them all), or ‘transforms’ the individuals into subjects (it transforms them all) by that very precise operation which I have called interpellation or hailing, and which can be imagined along the lines of the most commonplace everyday police (or other) hailing: ‘Hey, you there!’

The class (or class alliance) in power cannot lay down the law in the ISAs as easily as it can in the )repressive) State apparatus, not only because the former ruling classes are able to retain strong positions there for a long time, but also because the resistance of the exploited classes is able to finds find means and occasions to express itself there, either by the utilization of their contradictions, or by conquering combat positions in struggle.