This chapter examines how the EU's crises unfold in a functionally differentiated society, and shows that the pursuit of self-interests by rationally behaving actors, although originally introduced as part of an economic way of integration, developed into a general regulative principle that transcended the constitutive frameworks of functional differentiation. It argues that politics, economics and law in the EU have different potentials to arrive at more promising ways of crisis management, but not all of them are equally viable under conditions of functional differentiation and when taking seriously the different ambits and scopes of politics, economy and law. The chapter concludes by suggesting rethinking the 'motor of the integration process', not only but especially in light of the many crises the EU faces. It shows how the distinction can help one understand the implications of a crucial decision of the early years of European integration that continues to influence not only the integration process, but also the EU's crisis management.