(CNN)Many historians have pointed out that we live in unprecedented times. The period since 1945 has been marked by the absence of war between the world's major powers. Most of prior human history is a tale of economic mercantilism, political conflict and repeated war. Since 1945, we have lived in what John Lewis Gaddis dubbed the "Long Peace." Through the Long Peace we have also had decades of rising incomes, living standards and health throughout the world, especially in the United States.
Trump is changing the international order
When Roosevelt was beginning to design his system, he was the dissenter. The dominant foreign policy ideas in America at the time were represented by a movement called "America First." Nativist, isolationist and anti-Semitic, the movement held that an outward-oriented America was a policy for suckers. It took Hitler and World War II to make Americans recognize that, for a country of America's size and scale, isolation and narrow self-interest would lead to global insecurity and disaster. One wonders what it will take to make today's America Firsters relearn that same lesson.