LOUIS ALTHUSSER builds on the work of Jacques Lacan to understand the way ideology functions in society. He thus moves away from the earlier Marxist understanding of ideology. In the earlier model, ideology was believed to create what was termed "false consciousness," a false understanding of the way the world functioned (for example, the suppression of the fact that the products we purchase on the open market are, in fact, the result of the exploitation of laborers). Althusser explains that for Marx "Ideology is [...] thought as an imaginary construction whose status is exactly like the theoretical status of the dream among writers before Freud. For those writers, the dream was the purely imaginary, i.e. null, result of the 'day's residues'" (Lenin 108). Althusser, by contrast, approximates ideology to Lacan's understanding of "reality," the world we construct around us after our entrance into the symbolic order. (See the Lacan module on the structure of the psyche.) For Althusser, as for Lacan, it is impossible to access the "Real conditions of existence" due to our reliance on language; however, through a rigorous"scientific" approach to society, economics, and history, we can come close to perceiving if not those "Real conditions" at least the ways that we are inscribed in ideology by complex processes of recognition. Althusser's understanding of ideology has in turn influenced a number of important Marxist thinkers, including Chantalle Mouffe, Ernesto Laclau, Slavoj Zizek, and Fredric Jameson. (See, for comparison, the Jameson module on ideology.)

Althusser posits a series of hypotheses that he explores to clarify his understanding of ideology:

1) "Ideology represents the imaginary relationship of individuals to their real conditions of existence" (Lenin 109). The traditional way of thinking of ideology led Marxists to show how ideologies are false by pointing to the real world hidden by ideology (for example, the "real" economic base for ideology). According to Althusser, by contrast, ideology does not "reflect" the real world but "represents" the "imaginary relationship of individuals" to the real world; the thing ideology (mis)represents is itself already at one remove from the real. In this, Althusser follows the Lacanian understanding of the imaginary order, which is itself at one step removed from the Lacanian Real. In other words, we are always within ideology because of our reliance on language to establish our "reality"; different ideologies are but different representations of our social and imaginary "reality" not a representation of the Real itself.

2) "Ideology has a material existence" (Lenin 112). Althusser contends that ideology has a material existence because "an ideology always exists in an apparatus, and its practice, or practices" (Lenin 112). Ideology always manifests itself through actions, which are "inserted into practices" (Lenin 114), for example, rituals, conventional behavior, and so on. Indeed, Althusser goes so far as to adopt Pascal's formula for belief: "Pascal says more or less: 'Kneel down, move your lips in prayer, and you will believe'" (Lenin 114). It is our performance of our relation to others and to social institutions that continually instantiates us as subjects. Judith Butler's understanding of performativity could be said to be strongly influenced by this way of thinking about ideology.

3) "all ideology hails or interpellates concrete individuals as concrete subjects" (Lenin 115). According to Althusser, the main purpose of ideology is in "'constituting' concrete individuals as subjects" (Lenin 116). So pervasive is ideology in its constitution of subjects that it forms our very reality and thus appears to us as "true" or "obvious." Althusser gives the example of the "hello" on a street: "the rituals of ideological recognition [...] guarantee for us that we are indeed concrete, individual, distinguishable and (naturally) irreplaceable subjects" (Lenin 117). Through "interpellation," individuals are turned into subjects (which are always ideological). Althusser's example is the hail from a police officer: "'Hey, you there!'" (Lenin 118): "Assuming that the theoretical scene I have imagined takes place in the street, the hailed individual will turn round. By this mere one-hundred-and-eighty-degree physical conversion, he becomes a subject" (Lenin 118). The very fact that we do not recognize this interaction as ideological speaks to the power of ideology:

what thus seems to take place outside ideology (to be precise, in the street), in reality takes place in ideology [....] That is why those who are in ideology believe themselves by definition outside ideology: one of the effects of ideology is the practical denegation of the ideological character of ideology by ideology: ideology never says, "I am ideological." (Lenin 118)

4) "individuals are always-already subjects" (Lenin 119). Although he presents his example of interpellation in a temporal form (I am interpellated and thus I become a subject, I enter ideology), Althusser makes it clear that the "becoming-subject" happens even before we are born. "This proposition might seem paradoxical" (Lenin 119), Althusser admits; nevertheless, "That an individual is always-already a subject, even before he is born, is [...] the plain reality, accessible to everyone and not a paradox at all" (Lenin 119). Even before the child is born, "it is certain in advance that it will bear its Father's Name, and will therefore have an identity and be irreplaceable. Before its birth, the child is therefore always-already a subject, appointed as a subject in and by the specific familial ideological configuration in which it is 'expected' once it has been conceived" (Lenin 119). Althusser thus once again invokes Lacan's ideas, in this case Lacan's understanding of the "Name-of-the-Father."

Most subjects accept their ideological self-constitution as "reality" or "nature" and thus rarely run afoul of the repressive State apparatus, which is designed to punish anyone who rejects the dominant ideology. Hegemony is thus reliant less on such repressive State apparatuses as the police than it is on those Ideological State Apparatuses (ISAs) by which ideology is inculcated in all subjects. (See the next module for an explanation of ISAs.) As Althusser puts it, "the individual is interpellated as a (free) subject in order that he shall submit freely to the commandments of the Subject, i.e. in order that he shall (freely) accept his subjection, i.e. in order that he shall make the gestures and actions of his subjection 'all by himself'" (Lenin 123).