I know post colonial studies which is a critical theory began with Orientalism which uses Foucault's concept of discourse. But also Frankfurt School is widely credited with finding critical theory since they wanted to reform marxism and change it from its singular focus on class to showing how western society in general perpetuated power hierarchies aka critical theory ? Whereas postmodernists use genealogies to show that all "Truths" are usually only dominant because of their contribution to re-affirming power. For eg. the universality of representative bourgeois democracy helps perpetuate patriarchy and majority rule.
-
I think the modern term critical theory coalesced from many parallel currents of thought in philosophy and social science. When you ask where specifically critical theory came from, it sounds somewhat like you think there was a specific theory written by a specific group of people, but I think it emerged in culture in general in many places and was the result of interactions of various theories. According to Wikipedia the term did originate from the Frankfurt School, but I don't know at what point people began mixing theories of the "postmodern" with ideas from "critical theory".– Peter ElbertJul 3, 2022 at 12:43