Serious scholars still debate whether the Civil War was necessary, never mind the more obvious "wars of choice" such as World War I, the War of 1812, the Spanish-American War, the Korean War, wars in Vietnam and Kosovo, and the Persian Gulf War. To a certain brand of American isolationist, even World War II was unnecessary and counterproductive. So there is nothing remarkable about polls showing Americans wondering whether the recent Iraq war was "worth it." It is a great American myth, voiced by John Kerry last year, that the nation goes to war only when there is no question...