America also benefits from its distinctive political ideology and institutions. Founded on Enlightenment ideals rather than a conqueror's battle lines or a monarch's bloodlines, they distributed power among the states and branches of the federal government. Along with a dissident religious tradition, this has meant that in peacetime the United State is in an almost constant state of turmoil, which is evident even when it ventures abroad. "Americans, in foreign policy, are torn," writes Robert Kagan, an American historian. "Reluctant, then aggressive; asleep at the switch, then quick on the trigger; indifferent, then obsessed, then indifferent again. They are a revolutionary power, but think they are a status-quo power."
-as excerpted from this essay in The Economist