For much of history, most of the people an individual might interact with daily were familiar members of their own group. An individual in a major city today, however, might interact with more strangers than a hunter-gather met in a lifespan. Our populations and societies are now significantly larger. Knowing about lives elsewhere, and having the ability to affect them, means having responsibility to those lives. Our ideas and institutions have been shaped by living in local groups, but we must adapt to being part of a “global tribe” (xiii).

Appiah proposes the term cosmopolitanism. He traces the history of the term, which originated with the Cynics in the fourth century BC, for whom “citizen of the cosmos” meant skepticism toward a traditional loyalty to one’s polis, or city (xiv). Appiah follows the idea as developed by the Stoics through to Christian thought and Enlightenment thinking. He identifies two important strands to modern cosmopolitanism: (1) we have obligations to other people, even if they are not members of our immediate community; and (2) we respect the particular and distinctive practices between communities as part of the value of human lives.

Some who favor cosmopolitanism argue that no national, local, or even personal allegiances should ever hold us.