every american old enough can remember what he was doing, and thinking, when he first heard of the attack on Pearl Harbor, the assassination of John F. Kennedy, and the attacks on September 11. These may not have been the most momentous events of recent American history, but they were the most shocking, for they were the most unexpected. Before Pearl Harbor, Americans feared German submarine attacks in the North Atlantic or a Japanese attack on the Philippines would lead to war; no one expected Pearl Harbor to be the target. Americans had experience of war-weary presidents–Lincoln and Roosevelt–dying at the moment of victory; but no one expected the death of the youthful Kennedy in the middle of his first term.

In the America of Sept. 10, 2001, there were some in the foreign policy elite worried about a future confrontation with China, others uncertain how we would get on with a not totally reformed Russia, others concerned about developments in the Third World. But no one imagined that Islamist fanatics would send airliners crashing into the World Trade Center, the Pentagon, and (if the heroes of United Airlines Flight 93 had not prevailed) possibly the Capitol or the White House.

These disasters punctured the American idea that this is a country specially graced by providence. We have had, mostly, a happy history. American colonists in the 18th century were already, by the standards of protein consumption, the most affluent people in the world. The American Revolution produced not the tyranny of the French Revolution but a stable republic, of government both popular and limited, with guaranteed rights and a system of law that permitted unparalleled economic prosperity. Most Americans are inclined to share the view, held by Washington, Lincoln, both Roosevelts, and Reagan, that this is a specially blessed land, a city on a hill with a mission to teach the world how to build societies of liberty and order, conscience, and affluence.

Pearl Harbor, the Kennedy assassination, and September 11 each reintroduced us to the tragedy of history. They showed us that there is such a thing as evil and that we are not immune to its attacks. We should have known this from the one evil strain in our own history, the subordination of one race to another, an evil that thrust us into civil war and with which we grapple still.

Now we must grapple with and defeat those who attacked us on September 11 and their allies as we grappled with and defeated those who attacked us at Pearl Harbor and their Axis partners some 60 years ago. It is a different task and perhaps a more difficult one. But if the identity of the enemy is less clear and his citadels more difficult to locate, the heart of the threat is just as clear: a set of totalitarian ideas and beliefs that are antithetical to the ideas of liberty and order, which are the heart of American nationhood.

Sixty years ago, the ideas that threatened us were Nazism and Japanese imperialism. They were not just the ideas of a few fanatics but were the fervent beliefs of millions of people. That meant there was no alternative but war–an industrial era war, waged with huge armies and great masses of industrial-era machines to the point of unconditional surrender. And beyond: America's postwar governance of Germany and Japan extirpated evil ideas and established enduring liberal democracies. What we are waging now is a postindustrial war: a war that will be won by high-skill special forces and high-tech sophisticated machines. But it will not finally be won until we change not only regimes but minds.

This is a task pressed on us by history. For we Americans have been entrusted by circumstance with the duty of defending and advancing ideas that can free and enrich people around the world. The shock of Pearl Harbor told us that we must defeat specific nations in the thrall of evil ideas, and we did. The shock of the Kennedy assassination made us feel that the world was disordered and unpredictable, and for a time we floundered. The shock of September 11 showed us that we must break the power of ideas that threaten our civilization–and we must prevail again.