Much of the discussion on cosmopolitanism and nationalism has focused on their different normative views. The purpose of this article is to shift the attention away from the normative debate to the metatheoretical argument about how we determine moral and political principles independently of each other. I argue that the discussion among proponents of cosmopolitanism and contextualist models boils down to latent methodological and metatheoretical assumptions about what selection of facts are considered politically relevant. In the article, I explore what I call ‘the indeterminacy failure’ of moral cosmopolitanism, that is, the view according to which moral principles fail to determine what political-institutional level might be preferable; and the ‘indeterminacy failure’ of liberal nationalism, that is, the view according to which national identity fails to determine moral principles. In opposition to dichotomist cosmopolitan models (including various nonideal types of moral cosmopolitanism) and alternative contextualist approaches (including the practice-dependence thesis and liberal nationalism), I promote a ‘split-level’ model that is set to avoid the difficulties in the other approaches. The split-level corrects the indeterminacy failures of cosmopolitanism and contextualism by distinguishing clearly between the level of moral theorising and the level of political theorising.