The concept of Ideological State Apparatus (ISA) is coined by French Marxist philosopher Louis Althusser. This concept mainly refers to what is known in contemporary political discourse as ‘soft power’, i.e. the form of power that operates by means of ideological persuasion rather than violent, physical coercion. The latter ‘hard power’ form is referred to as the Repressive State Apparatus (RSA). Ideology, for Althusser, is an essential part of the smooth running of any form of government, even the most violent and repressive governments, because without the active support of at least a portion of the general population it cannot hope to succeed.
Power, Althusser argues, does not only come out of the barrel of a gun but must also be crystallized in the minds of individual subjects. In so saying, Althusser separates the state from the apparatuses the state requires in order to maintain itself, his implication being that revolutionaries not only need to take power, they also need to control the apparatuses of power. The Ideological State Apparatus is not unified like the RSA but consists rather of a loose coalition of largely private or non-governmental entities such as churches, schools, universities, trade unions, the media, and even the family. Each of these entities is semi-autonomous, which is to say they have their own area of efficacy and are not necessarily subordinated in any direct way to a higher authority. In order to explain this collective but independent acting together, Althusser constructed the notion of structural causality. Despite their diversity, all ISAs contribute to a single result, namely the reproduction of the relations of production.