To understand Althusser’s essay you must first have a grasp on Marx. Marx created a theory for understanding how Western society functions according to class. He argued that the superstructure was an umbrella-like, overarching body of rule. It includes direct forms of government and also ideology, such as, religion and law. Below the superstructure is the economic base. According to Marx changes can be made relatively easily to the economic base. However, he argues that it is much more difficult to impact the superstructure. This is why it is very hard to influence society as a whole.
Althusser builds off of Marx’s theory by expanding on how ideology functions. He breaks down ideology into two parts. The first is the ideological state apparatus. This accounts for intangible places of thought creation and reproduction. For example, family, church, television, sports, and politics are all sites of the ideological state apparatus. The ideological state apparatus is diverse and expansive. It comes from all angles and works persuasively.
Conversely, state apparatuses are more obvious, very tangible spaces of ideology. For example, police and prisons are agencies of the state apparatus. Althusser believes that the state apparatus is differentiated in its more apparent and direct use of violence and force. In addition, the state apparatus is invasive and has access to the private lives of citizens. For example, the police can enter our homes with a search warrant. He believes that the state apparatus targets the working class due to their vulnerabilities. While the state apparatus uses force, the ideological state apparatus requires buy in from the public. This was a ground-breaking theory because it highlights the two ways in which the state has influence. One is obvious, while the other is more covert but pervasive.