Moishe Postone in a 2006 paper states that post-modernism ontologises indeterminacy, so does the notion of overdetermination employed by Althusserians.
To the degree we choose to use “indeterminacy” as a critical social category, then, it should be as a goal of social and political action rather than as an ontological characteristic of social life. (The latter is how it tends to be presented in poststructuralist thought, which can be regarded as a reified response to a reified understanding of historical necessity.) Positions that ontologize historical indeterminacy emphasize that freedom and contingency are related. However, they overlook the constraints on contingency exerted by capital as a structuring form of social life and are, for this reason, ultimately inadequate as critical theories of the present. Within the framework I am presenting, the notion of historical indeterminacy can be reappropriated as that which becomes possible when the constraints exerted by capital are overcome. Social democracy would then refer to attempts to ameliorate inequality within the framework of the necessity imposed structurally by capital. Although indeterminate, a postcapitalist social form of life could arise only as a historically determinate possibility generated by the internal tensions of capital, not as a “tiger’s leap” out of history.
“History and Helplessness: Mass Mobilization and Contemporary Forms of Anticapitalism”
Beyond Capital 