You would never guess it from the news, but we're living in a peculiarly tranquil world. The new edition of "Peace and Conflict," a biennial global survey being published next week by the University of Maryland, shows that the number and intensity of wars and armed conflicts have fallen once again, continuing a steady 15-year decline that has halved the amount of organized violence around the world. Those statistics are no solace for mourners in Iraq and Darfur. But so many other people are now living in peace that you don't have be a dreamer like John Lennon to take...