The growing literature on cosmopolitanism represents a major advance in political theory, as well as an effort to address the new circumstances of politics usually thought of as “globalization.” While this literature aims to reconstruct a political ethic, it mostly leaves out the unreflected elements of the social imaginary which must ground the solidarity necessary for popular allegiance to new ethico-political demands. This essay argues that the expansion of political horizons associated with the rise of territorial sovereignty in 18th Century Europe presented similar issues. I explore how, through the otherwise unsatisfactory notion of a civil religion, Rousseau sought to address the problem of solidarity.