The Integrity of the Single Market. The Cosmopolitan Case Against Differentiation

The European Union does not permit states to participate in only a part of the Single Market. Its position is that differentiated integration would undermine the integrity of the Single Market. Why this is so, and what it is that keeps the Single Market intact, is not yet clear, however. In this article I explain the position of the EU and offer a justification for it. I argue that Single Market justice, which I reconstruct as a form of Kant's cosmopolitan justice, holds the Single Market together. Single Market justice is the equal distribution of market rights among the nationals of Single Market states. Partial participation in the Single Market entails that market rights are distributed unequally; their distribution comes to depend on the nationality and residency of Single Market state nationals, which conflicts with Single Market justice. I argue that it is not undemocratic to reject a proposal for partial participation in the Single Market.