Tackling global injustice requires appropriate and effective institutions as well as cosmopolitan solidarity. This paper assumes that the ‘constitutionalized world society’ theorized by Habermas offers a viable proposal to make the protection and promotion of human rights more feasible. His account of solidarity, however, reveals a conundrum: If strong forms of solidarity grow out of shared political institutions and a related collective identity, but it is precisely those institutions that we need to enhance at the global level, then how can (...) we build sufficient solidarity to support this process? Habermas relies on a global consensus on human rights, but I argue that his version of cosmopolitan solidarity is too weak to motivate the measures needed to fully realize economic, social and cultural rights and the package of institutional reforms that he proposes. We thus need a narrative of the human condition that can lend additional support to the idea of human rights and cosmopolitan duties. I find the seeds of such a position, which I call cosmocommonism, in the work of Nancy. Having shown how this can motivate cosmopolitanism and support for human rights, I then consider in the conclusion its compatibility with the political institutions that Habermas proposes. (shrink)