Author Robert Wright explains "non-zero-sumness," a game-theory term describing how players with linked fortunes tend to cooperate for mutual benefit. This dynamic has guided our biological and cultural evolution, he says -- but our unwillingness to understand one another, as in the clash between the Muslim world and the West, will lead to all of us losing the "game." Once we recognize that life is a non-zero-sum game, in which we all must cooperate to succeed, it will force us to see that moral progress -- a move toward empathy -- is our only hope.