This paper examines how radical realism, a form of ideology critique grounded in epistemic rather than moral normativity, can illuminate the relationship between ideology and political power. The paper argues that radical realism can has both an evaluative and a diagnostic function. Drawing on reliabilist epistemology, the evaluative function shows how beliefs shaped by power differentials are often epistemically unwarranted, e.g. due to the influence of motivated reasoning and the suppression of critical scrutiny. The paper clarifies those mechanisms in order (...) to address some recent critiques of radical realism. The paper then builds on those clarifications to explore the how tracing the genealogy of legitimation stories can diagnose the distribution of power in society, even if ideology does not play a direct stabilising role. This diagnostic function creates a third position in the debate on ideology between culturalists and classical Marxists, and it can help reconciling aspects of structural and relational theories of power. (shrink)