Sir David Cannadine, a professor of history at Princeton University, has taught at the University of Cambridge and Columbia University. His most recent book, The Undivided Past: Humanity Beyond Our Differences, has just been published by Alfred A. Knopf.

When Saul Bellow was awarded the Nobel Prize in Literature, in 1976, he concluded his acceptance speech with these wise, generous, and tolerant words: "There is no simple choice between the children of light and the children of darkness." But a quarter of a century later, Bellow's fellow American, President George W. Bush, took a very different view, insisting that there was, indeed, such a straightforward choice between good and evil. "When I was coming up," he opined, "it was a dangerous world, and you knew exactly who they were. It was us versus them. Today we're not so sure who the they are, but we know they're still there." Here was a view of the world, of human association and of human nature, that assumes a polarized, Manichean division, built around collective identities that are internally coherent and homogeneous, and that are always latently or actually in conflict. The choice between them is, therefore, very simple and very clear.

Such a vision of a deeply sundered humanity has been urged and advocated throughout much of human history, by political leaders and public figures, clerics and religious leaders, pundits and commentators, and academics in many disciplines wedded to the importance of "difference," the significance of "identity," and the enduring existence of conflict. From this perspective, collective identities and confrontations are the key to understanding the past, explaining the present, and predicting the future.

In such claims, one particular collective identity—be it religion, nation, class, gender, race, civilization—is deemed more important than any or all others, and the construction of an affirming historical narrative of victimhood, struggle, and eventual triumph is seen as essential to constructing that identity. But the result is a view of the human condition that is partial and pessimistic, and more than a touch paranoid, and that gives insufficient attention to how people actually live out their lives, and what they have in common....