Promising new solutions or risking unprecedented harms, science and its technological affordances are increasingly portrayed as matters of global concern, requiring in-kind responses. In a wide range of recent discourses and global initiatives, from the International Summits on Human Gene Editing to the Intergovernmental Panel on Climate Change, experts and policymakers routinely invoke cosmopolitan aims. The common rhetoric of a shared human future or of one humanity, however, does not always correspond to practice. Global inequality and a lack of accountability within most institutional contexts of international governance render these cosmopolitan proclamations of ‘one human community’ incoherent and even harmful. More generally, there exists no shared normative standard for the cosmopolitan governance of science, with which such global initiatives could be evaluated. Taking a broadly philosophical perspective, the present paper aims to better understand this problem situation, identifying three high-level challenges global governance of technoscience: problematic ideals of technology and science, the unjust formation of “global” concerns, and the limitations of cosmopolitan theory. By holistically engaging these jointly empirical and normative sites of inquiry, scholars can better support humanity’s re-imagination of technoscientific practices within and beyond the nation-state.