In the established church of foreign policy, no creed currently commands greater devotion than democratic pacifism: democracies share a form of government that prevents war between them. The idea is not new. Its academic champions credit a 1795 essay by Immanuel Kant, but the basic points had already been made by Jean-Jacques Rousseau and Thomas Paine and criticized, as familiar folk theory, by Alexander Hamilton. Enthusiasm grew in the 1980s and 1990s, when the brilliant Kant-revival essays of Michael Doyle were followed by a worldwide outbreak of democracy. Today scholars often ask why democracy is mutually pacific, but rarely whether it is. Endorsed by some members of the George H. W. Bush’s administration, democratic pacifism drove the Clinton Doctrine of peace and security through a crusade for democracy. “The best strategy to ensure our security and to build a durable peace,” President Clinton said in his 1994 State of the Union address, “is to support the advance of democracy elsewhere. Democracies don’t attack each other.” So far president George W. Bush has preached more cautiously, but from the same text, his caution directed less at the effects of democracy than at the efficacy of democratization.