This article argues that a distinction between the public and the private is both desirable and feasible in times of global governance, at least as a regulative idea. The confusion surrounding this distinction originates in different understandings of the relationship between state and society in liberalism and republicanism. Discourse theory with its idea of the co-origin of democracy and human rights reconceptualises the relationship between state and society in a way that does justice to both liberal and republican approaches. Accordingly, the public/private distinction is crucial for the realisation of democracy and freedom. Classifying an act as public or private determines what kind of legitimacy it requires. The article then recalibrates discourse theory to face the challenges of global governance, shifting its focus from hard law to a broader notion of authority, and from the state to a pluralistic, cosmopolitan world order composed of multiple overlapping communities. A community is characterised by communicative action and a common identity. In such a setting, public authority is the authority exercised on behalf of a community in relation to its members. In relation to non-members, the same act may constitute an exercise of private authority. It is a different question whether such authority is legitimate. Some examples illustrate the approach.