This Element explores the uncertain future of public policy practice and scholarship in an age of radical disruption. Building on foundational ideas in policy sciences, we argue that an anachronistic instrumental rationalism underlies contemporary policy logic and limits efforts to understand new policy challenges. We consider whether the policy sciences framework can be reframed to facilitate deeper understandings of this anachronistic epistemic, in anticipation of a research agenda about epistemic destabilization and contestation. The Element applies this theoretical provocation to environmental policy and sustainability, issues about which policymaking proceeds amid unpredictable contexts and rising sociopolitical turbulence that portend a liminal state in the transition from one way of thinking to another. The Element concludes by contemplating the fate of policy's epistemic instability, anticipating what policy understandings will emerge in a new system, and questioning the degree to which either presages a seismic shift in the relationship between policy and society.