Louis Althusser was a major proponent of structural Marxism. He argued that Marx underwent an "epistemological break" where his early works were humanist but his later works like Capital advocated an objective, scientific approach. Althusser believed society consisted of a base of economic structures and a superstructure of political and ideological institutions that help reproduce capitalism. He defined the Repressive State Apparatus (RSA) that uses force and the Ideological State Apparatus (ISA) like education that promotes capitalist ideology through indoctrination. Althusser was influential in the 1960-70s but later faced criticism for being too abstract and deterministic.