Truth-subversion practices, which populist leaders utilize for political domination, are a significant source of current pressure on the Liberal International Order (LIO). Truth-subversion practices include false speak (flagrant lying to subvert the concept of facts), double speak (intentional internal contradictions in speech to erode reason), and flooding (the emission of many messages into the public domain to create confusion). Aiming to destroy liberal truth ideals and practices, truth subversion weakens epistemological security; that is, the experience of orderliness and safety that results from people's and institutions’ shared understandings of their common-sense reality. It privileges baseless claims over fact-based opinions, thus creating communities of the like-minded between which communication becomes impossible. Truth subversion challenges the LIO's three key institutions: democracy, markets, and multilateralism. If truth-subversion practices prevail, societal polarization, inaccurate information, and emotional inflaming strain democracy and human rights protections. Markets that depend for their functioning on accurate information can falter, and multilateralism that relies on communication and reasoned consensus can decay. International relations (IR) scholarship has recognized knowledge production practices as a key feature underlying the LIO, but has not yet identified challenges to those practices as a threat for the LIO. We discuss what the discipline can do to alleviate its blind spots.