History is drenched in bloodshed unleashed by human conflict. Nor is there much evidence that humanity’s violent inclinations are decreasing. World wars, human rights abuses, ethnic cleansing, and genocide characterized much of the twentieth century. There is no assurance that the twenty-first century will be better, but if moral improvement is to take place, the philosopher Kwame Anthony Appiah believes that a revival of an ancient ideal, cosmopolitanism, will be essential in that process.

Appiah’s project is to identify and defend an ethical outlook that can work in what the subtitle of Cosmopolitanism calls “a world of strangers.” The twenty-first century world is both the same and different from the world of the fourth century b.c.e., when ancient philosophers coined the term “cosmopolitan,” using it to refer to a “citizen of the cosmos.” Then and in contemporary life as well, one has normally been a citizen of a particular placecity, state, or countrynot of the universe. Then and in contemporary life as well, the world has been full of strangers, people with whom one has contact but who are not members of one’s family or particular community. In the twenty-first century, however, the world’s population is approaching nine billion. In space and time, people live closer than ever, but never have there been so many potentially hostile strangers.

Amid these similarities and differences, while immense changes in the world have taken place and indeed partly because of them, a long-standing tradition has grown over the centuries: a person could and should be a citizen of the world. Cosmopolitanism is an idea with links to a variety of significant and long-standing ideals, including the view that all human beings are members of one family, the conviction that there are universal human rights and obligations, and the hope that there can be a cooperating league of nations that advances goals that are beneficial for humankind. On a personal level, cosmopolitanism embodies much needed virtues that include respect for people who are different from ourselves, resistance against discrimination and prejudice, and hospitality toward strangers.

Appealing though these ideals may be, Appiah recognizes that the history of cosmopolitanism has its problems. How, for example, does this outlook fit with the fact that human life is always lived in specific times, places, and cultures, which require loyalties that are particular and local? The cosmopolitan person, it could be argued, will be rootless, which is scarcely a desirable way to live. Such people may profess impartiality or allegiance to “humanity” but care too little for individual persons and communities. Another problem is that cosmopolitanism may not be as universal as it sounds. Values, it seems, are relative to particular times and places. No individuals or groups, not even philosophers, have a privileged access to absolute and objective truth. In fact, cosmopolitanism may be cultural or national imperialism in disguise. Furthermore, the objections continue, cosmopolitanism is simply unrealistic because differences between human groups are too strong. In the twenty-first century a clash of civilizations, reflected especially in terrorism and a war against it, has eclipsed cosmopolitan dreams. Yes, there is talk about “globalization,” but that concept is really about international economic competition that may be intensifying differences and inequalities even as it homogenizes the world’s products and dominant patterns of communication and consumption. There is talk about “multiculturalism,” but it is not clear that its often superficial acknowledgment of cultural and ethnic differences has produced the respect for others that is needed to reform the deeply entrenched social structures in which poverty and injustice dwell.

Appiah recognizes the force of these objections, but far from taking them to be fatal, he thinks that they can lead to a reaffirmation of cosmopolitanism’s importance. Rootlessness is no virtue, but that bleak condition is not what Appiah’s cosmopolitanism entails. To the contrary, his ethics in a world of strangers underscores that differences between people and particularities about them are crucial for meaningful lives. It follows that life cannot be lived well in conditions where differences and particularities are not respected. Cosmopolitanism affirms the importance of respect for differences and particularities. This respect, however, cannot be practiced by one person or group and ignored by others. The ethical logic of cosmopolitanism insists that the respect must be...

(The entire section is 1901 words.)