This well-known reflection by the seventeenth century English poet John Donne is a timeless expression of the idea we should feel solidarity not just with our immediate relatives, clan or nation, but with the whole human family. These ideas have a philosophical formulation in the idea of cosmopolitanism. Yet what is the basis of the idea that we should feel care for and responsibilities towards all human beings? Is it not right that our responsibility should be restricted to those closest to us, our family and friends or perhaps to our village, city or nation? These questions are central to discussions of ethics more broadly, but have come to the fore with the increasing prominence of debates around the concept of ‘citizenship’ in recent years. Citizenship has become a focal point for a variety of reasons, including the increasingly diverse nature of many formerly homogeneous societies through migration, debates over the granting of official residents’ rights to undocumented workers, as well as disillusionment with the conventional political processes and institutions and the consequent decline in voter turnout in some countries.