To be a cosmopolitan--i.e., a citizen of the world first and only secondarily a member of a particular nation--is an ideal that has a long history. It dates back to the ancient Greek philosopher Diogenes of Sinope in the third century BCE. If someone asked him where he came from, he would only reply, "I am a citizen of the world."In this overview of the cosmopolitan ideal, philosopher Peter Kemp argues that in the twenty-first century cosmopolitanism...