Many Americans today feel a sense of personal vulnerability they have never felt before, even during the Second World War. Terrorism, undeterred and very likely intensified by our victory in Iraq, has given a new and scary dimension to war.

The vast majority of us agree on the objective of eradicating terrorism, but we sometimes disagree on the best means of attaining that objective. The idea is spreading that, when mortal danger threatens, we must suspend discussion and debate, rally 'round the flag, and allow the president to be the unquestioned single voice of a nation.

This belief raises a couple of questions I believe history might help us answer. First: Do a democratic people have a moral obligation to cease debate and dissent in times of war? Second: Did our ancestors abstain from debate and dissent when their government took them to war? These two questions presuppose a third: What is the true nature of patriotism anyway?

The answer to the first question is that going to war does not abrogate freedom of conscience, thought and speech. In the midst of World War II, the Supreme Court held that compelling kids in public schools to salute the flag and recite the Pledge of Allegiance violated the First Amendment and was therefore unconstitutional. This decision, handed down on Flag Day 1943, was considered then to be a pretty good statement of why we were fighting.

The role of dissent in the run-up to war is crucial. Before sending young Americans to kill and die in foreign lands, a democracy has a sacred obligation to permit full and searching discussion of the issues. There is no obligation to bow down before a reloaded imperial presidency.

Nor does the actuality of war change the situation. As Theodore Roosevelt said in 1918 during the First World War, "To announce that there must be no criticism of the president... is not only unpatriotic and servile, but is morally treasonable to the American public."

Sen. Robert A. Taft, a much revered Republican leader, went a step further when he declared after Pearl Harbor that, "Too many people desire to suppress criticism simply because they think it will give some comfort to the enemy... . If that comfort makes the enemy feel better for a few moments, they are welcome to it ... because the maintenance of the right to criticism in the long run will do the country maintaining it a great deal more good than it will do the enemy."

There is little more insolent or despicable than public officials, like the attorney general of the United States, who cry that those who dare question their acts are giving aid and comfort to the terrorists.

As for the second question, the historical record shows that Americans have never refrained from dissent or criticism in wartime. Even in the American Revolution, a third of the colonists opposed the drive toward independence. From the War of 1812 through the Mexican War and the Civil War to the wars in Korea and Vietnam, criticism of the White House has thrived.

Historically, there is nothing sacrosanct about presidents in wartime. Indeed, no president has any right to send young Americans to kill and die in foreign lands without the most frank and uninhibited discussion and debate. This is all the more the case when a fundamental transformation in the strategy of national security promises a vista of presidential wars stretching far into the future, and this very transformation has taken place recently in our country.

For more than 40 years after the Second World War, our national strategy was based on containment and deterrence. This strategy enabled the democracies to win the Cold War peacefully. Had the occasional voices calling for preventive war against the Soviet Union been heeded, few of us would be here today.

Now our president has proclaimed a new doctrine of "anticipatory self-defense," which is simply a fancy term for preventive war. In fact, the policy of anticipatory self-defense is the same policy that imperial Japan employed in its attack on Pearl Harbor on a date that still lives in infamy. Today, it is we Americans who live in infamy. The global wave of sympathy that engulfed the United States after 9/11 has given way to a global wave of fear and hatred of American arrogance.

Should America serve as the world's initiator of preventive war, its self-appointed judge, jury and executioner? As we struggle to make this decision, I would ask Americans to reflect on the words uttered by a president whom I had the honor and good luck to serve in the White House.

"We must face the fact," President John F. Kennedy said 42 years ago at the University of Washington, "that the United States is neither omnipotent nor omniscient... that we cannot right every wrong or reverse each adversity — and that therefore there cannot be an American solution to every world problem."

As to my third question: What is the nature of patriotism anyway?

True patriotism, I propose, consists of living up to the nation's highest ideals. Carl Schurz, a German emigrant who became an influential figure in 19th-century America, defined the true meaning of patriotism when he said: "Our country, right or wrong. When right, to be kept right; when wrong, to be put right."

Pulitzer Prize-winning historian and social critic Arthur M. Schlesinger Jr. was special assistant to President John F. Kennedy. This commentary was adapted from Schlesinger's 2003 commencement address Sunday at Whitman College, where he received an honorary doctorate of human letters. The entire text can be found at www.whitman.edu