Much traditional political philosophy asks whether a given belief, norm or institutional arrangement is actually justified or true, on its own philosophical merits. Critical theory, developed substantially by twentieth-century philosophers associated with what's often called the Frankfurt School, adds a genuinely different question alongside that one: whose interests does a given widely accepted idea, norm or institution actually serve in practice, and how might it help sustain existing relationships of power and domination, regardless of how rationally justified or self-evidently natural it might otherwise appear to those who accept it?
Ideas can serve power even when nobody involved is consciously scheming
Critical theory's central insight is that dominant ideas within a society aren't necessarily accepted purely because they're independently, objectively true or rationally compelling — they can also become widely and durably accepted, at least in part, because accepting them happens to serve the interests of those who already hold disproportionate social, economic or political power, whether or not any specific individual is consciously and deliberately promoting the idea for exactly that self-interested reason. An idea that portrays existing social arrangements as natural, inevitable or simply the way things have always been done can, on this view, function to discourage people from questioning or challenging those existing arrangements, whatever the idea's own explicit, surface-level content actually says, and regardless of whether anyone actually promoting the idea has any conscious intention along those lines at all.
Critique means uncovering assumptions a society's own common sense doesn't examine
Because this kind of power-sustaining function can operate entirely without conscious intent, critical theory places heavy emphasis on critique: actively examining and questioning a society's own widely shared, generally unexamined common-sense assumptions, specifically to uncover whose interests those assumptions might actually be serving beneath their surface, everyday plausibility. This critical stance is precisely what distinguishes critical theory from more traditional philosophical approaches that primarily ask whether a given belief is true or a given norm is justified on its own stated terms — critical theory instead asks a further, distinct question about the belief's actual social function and its relationship to existing power, treating that as a genuinely separate and equally important line of inquiry, not one that traditional truth-and-justification-focused philosophical analysis, on its own, is well equipped to answer.
What we're still unsure about
Critical theory's basic method and its historical development through the Frankfurt School are well documented in the history of twentieth-century philosophy. What remains genuinely, actively debated, both within critical theory and among its critics, is how reliably this kind of critique can actually be carried out without simply projecting the critic's own prior assumptions about power onto whatever idea is being examined — critics of the approach have long raised the concern that critical theory's own framework risks becoming difficult to falsify in practice, since any idea can, in principle, be argued to serve some existing power interest or another, a genuinely contested methodological question critical theorists themselves continue to grapple with rather than one the field treats as fully settled.
This sits inside Power, Domination & Critical Theory, one of seven topics in Political Philosophy, one of five domains in Philosophy, one of seventeen subjects the app can quiz you on.