Hardt and Negri (2001, p. 354) once remarked that 'political philosophy forces us to enter the terrain of ontology'. At a time when democracy's very future seems to be at stake, this statement assumes a renewed urgency. For, if the democratic project is once more under existential threat, rethinking the foundations of political thought and action is perhaps no longer the exclusive preoccupation of radical political thinkers but becomes the central task of contemporary democratic theory more broadly.Political ontologists have persuasively argued that our fundamental assumptions about the meaning and nature of our being in the world, about politics as a collective activity, and about the purpose of political philosophy are deeply interwoven; thinking and acting politically, as Arendt taught us, are inseparable. Philosophy is not simply an external discourse of knowledge that produces a scientific or 'objective' account of political life, separate from the actual practices, habits and affective commitments of individual or collective agents; nor can political life simply be reduced to procedures of validation based on intersubjective rules of communication.Yet, even if the so-called 'ontological turn' in political theory has rendered the liberal search for ontological neutrality or the Habermasian call for communicative 1 This Critical Exchange is the result of two workshops held at the University of Edinburgh and the University of St. Andrews in November 2016. We thank the commentators at these events -Nathan Coombs, Patrick Hayden, Tony Lang and Nick Rengger -for their helpful feedback on the presentations. For institutional support, we owe gratitude to our home universities and Edinburgh University Press. Finally, we are grateful to Andrew Schaap for inviting us to edit the papers for this journal. The five contributions included in this exchange draw on a variety of ontological approaches to the political, reflecting a broad range of concerns, both friendly and critical, to the much-analysed 'ontological turn' in political theory. In what follows, we shall draw out two themes that all contributions speak to, and suggest areas where a common ground is emerging, as well as domains where instructive divergences remain.The first theme concerns the translatability of fundamental ontology to the realm of politics. How straightforward or uninterrupted, in other words, is the transition from ontology to the political? The strong case for an ontology of the political is put forward in Oliver Marchart's contribution as part of his wider claim about the political nature of (social) being. Building on the Heideggerian distinction between the ontological and the ontic, Marchart argues that the added value of political ontology rests on the recognition that social order (or the social) is traversed by antagonism and that the different ontic ontologies of conflict, power, exclusion, subordination as well as their opposite ontologies of peace, harmony, association and pluralisation, are all expressions of the political, i.e...