Human beings have the unique ability to view the world in a detached way: We can think about the world in terms that transcend our own experience or interest, and consider the world from a vantage point that is, in Nagel's words, "nowhere in particular." At the same time, each of us is a particular person in a particular place, each with his own "personal" view of the world, a view that we can recognize as just one aspect of the whole. How do we reconcile...