Contemporary democratic theory is marked by two politically distinctive but epistemologically similar radicalisms: Deliberative and Platonist. Deliberative democrats seek to enhance the legitimacy and value of democratic outcomes by ensuring deeper, more discursive participation so as to approximate rational consensus around the self-evident public interest or to inculcate the ideal of public reasoning among citizens. Platonist democrats, responding to widespread evidence of public ignorance and irrationality, argue that participation should be limited to those who can do so from a position of expertise. What these radical positions have in common is an implied readiness to reject the fundamental democratic principle of minimal political equality for practically all citizens. In so doing, they risk subverting the desirable consequences of the institutional norms of today’s democracies: stability, anti-experimentalism and assumed non-contestability. Democracy’s main virtue – its tendency toward stability and resistance to revolution – is contingent upon the confidence that is placed in it by its citizens, which itself may be contingent upon the universal franchise. This thesis argues that theories of democracy are best understood in terms of their underlying presuppositions as to the scope – and potential scope – of human knowledge. It offers a new justification of democracy, suggesting specific consequentialist grounds while critiquing instrumental and deontic approaches to the problem. The thesis then turns to a consideration of the evidence for widespread public ignorance, and argues that such evidence cannot form a sound basis for Platonist, epistocratic arguments against the universal franchise. Deliberative democracy is similarly problematic, founded upon either the unattainable ideal of political consensus, or the badly-understood concept of ‘public reason’. Formal, demotic deliberation is intrinsically threatening to the democratic principle of political anonymity, and therefore, due to a host of well-documented social-psychological effects, to the universal franchise as well.