The interpretation of Marxist philosophy, as a part of Marxist studies, has been an important topic discussed by academics. Althusser's interpretation mainly reflected in attempting to define the attribute of Marxist philosophy. For early Althusser, Marxist philosophy is "the theory of theoretical practice"; and for late Althusser, Marxist philosophy is the "class struggle in the field of theory". This shift was closely related to his self-criticism since 1967.