Prior to and through World War II, 1939-1945, Althusser was involved in the Roman Catholic youth movement and advocated some of the church's more conservative teachings. During the Nazi occupation of France his thinking underwent a radical transformation, as he along with many others embraced Marxist ideologies. During this time he found himself involved with the French Resistance and attracted to one of its more prominent activists, Helene Legotier, eight years his senior and a member of the French Communist Party (PCF). In 1948 Althusser also joined the party. After the war Legotier continued her activism, while Althusser spent most of his time in academia. His lectures and writings became very influential and he was seen by many to be the party's most outstanding intellectual.
Althusser attempted to reconcile the views of French structuralism with those of Marxism by denying the primary role of the individual subject in the face of historically unfolding social structures. His most important works are For Marx (1965), Lenin and Philosophy (1969), and his contributions to a book of essays called Reading Capital, all of which were popular with student revolutionaries during the decade of social upheaval in the 1960s.
While many Marxists were looking for a more "humane" alternative to the totalitarianism unfolding in the Soviet Union and a way to resolve the split caused by the Chinese revolution, Althusser, taking the opposite tack, proposed a purely scientific approach, one he ascribed to the maturing Marx himself in For Marx, (1970). In Reading Capital and in Lenin and Philosophy and Other Essays (1971) he aimed at an objective account of how the total society works from its technological top down, generating the classes that run and do the work of a society. In the latter collection he described how such a structure operates through the languages we speak in common. These, he said, tend to instill in people their sense of reality and of themselves and their social roles, all in the interest of perpetuating the order of the given society: this is the thought-controlling use of language called "ideology."
Althusser sketched the underlying fabric of a society with the help of French "structuralist" theory. This led to the development of a comprehensive and intricate Marxist model for society as a whole, although access to the model is made difficult by Althusser's style and terminology.
In the structuralist view society cannot be understood through the subjective experience of individuals seen as in some way differentiated from the unfolding processes in which they are enmeshed. A society functions as a single organism in a manner determined by its technology and its modes of production. Every individual action is solely determined by its role in relation to that technology. Althusser's critique was partly in reaction to prevailing individualistic philosophies, as well as the increasingly embarrassing historical degenerations of the Marxist system under Stalin. Critics of Altusser's thinking largely objected to the extreme austerity of a system which denies the primacy of the subjective experience, insisting that a system which so entirely subordinates the individual to the "total" structure can never hope to sustain itself in any realm other than the theoretical.
The Chinese experience reminded Marxists that "contradictions" were the essence of their world view; unity is achieved only through the play of opposites, and all "wholes" contain and even consist of the struggles internal to them. As an organism breaks down food to build up nourishment, the state takes life to protect itself. Later disciples of Althusser would point out that both language and personality reveal inherent tensions in the makeup of the self. These as oppositions can be counted on to result in change and progress as they are products of the internalization of "idealistic" structures in the society as a whole. Marxists who preferred to see change as brought on from "the bottom up" (the oppressed, the working class) criticized Althusser for this scheme of resistance from "the inside out" (the repressed inside any group, body, or system: in the economic system, workers). Others found this to be one of his most fruitful new turns of thought.