Sept. 11, 2001, hangs over the American political scene like one of those mirrored disco balls, shining lights in every direction, its ultimate message hard to discern. No candidate can hope to be elected president without trying to focus one of those beams, finding a meaning to this day of tragedy that can make it part of a compelling narrative of American story.

But what part of the story should it be? A day that has changed everything, that means the United States' relationship to the rest of the world is forever altered? An aberrant event that, despite its huge cost in blood and dollars, should not dominate foreign and domestic policy? Something in between? Something else entirely?

That foundation for any such story will be the two iconic views of warfare that have dominated American political and social life for the last six decades. One comes from World War II. The other from Vietnam.

One is a triumphal story of good defeating evil. The other is a cautionary tale of avoiding the quagmire. Both provide compelling narratives for the post-Sept. 11 world that politicians will be drawing on as they tell their stories on the campaign trail.

As documentarian Ken Burns has so artfully reminded the country recently with his PBS series The War, World War II was special. For Americans, it began with an attack on unsuspecting soldiers and sailors. It ended with revelations of atrocities beyond anyone's imagination.

There was no doubt that it had to be fought. And there was absolutely no doubt that the United States was on the side of good and its opponents on the side of evil.

That might not have been that clear at the time, but it is now. "The vision of World War II as good vs. evil benefits from the collective memory," says Shawn Parry-Giles, a political scientist at the University of Maryland, College Park. "If you go back to the time period, it is not that clear-cut. Looking backward it is easy to have amnesia, to forget about the parts that were so complicated and complex."

The good-vs.-evil paradigm of World War II provided such a compelling narrative that it dominated the United States' approach to war, certainly for the next 25 years, and, it could be argued, up until today. This despite the fact that there might not have been another war in recorded history where that was as clear. That World War II is a historical outlier is rarely acknowledged.

Demonizing the enemy is as much a part of warfare as tactics and weapons. But traditionally, this was an ethnically based affair. The Germans wanted to beat up on the French, well, because they were French. No other reason was necessary. Certainly, the United States has invoked such feelings throughout its history.

"I think that we have had a more dramatic tendency than most countries to describe our enemies as evil, and have for a long time - certainly the yellow journalism of the Hearst papers did this in 1898, and both sides in the Civil War, and for a long time before that as well," says Ted Wid- mer, a historian who directs the John Carter Brown Library at Brown University.

In World War I, the Germans were painted as the brutal violators of Belgium, though most of the propaganda tales turned out not to be true. That led to skepticism about similar claims at the start of World War II. It was easier to demonize the Japanese, as it always has been for those not of European ancestry, including, to some extent, those Americans of Japanese ancestry interned for the duration of the conflict.

But the United States is, at its base, a nation founded not on ethnicity but on ideas. What gives the World War II paradigm its power is that the evil was in the form of an ideology - Nazism - not an ethnicity.

Though we visited incredible death and destruction on the civilian populations of Germany and Japan, soon enough the message was that the Germans and Japanese were our friends - our enemies were the Nazis and militarists who had led them astray. The war was thus a fight on our turf, not between people, but between ideas.

Never was that more apparent than in 1985 when President Ronald Reagan visited the German military cemetery in Bitburg that included graves of members of the Hitler's elite SS. Reagan said that day, "We can mourn the German war dead today as human beings, crushed by a vicious ideology." The soldiers buried in that cemetery, many of whom had tried their best to kill Americans, some of whom had certainly persecuted and perhaps killed Jews, were not the enemies, but fellow victims of ideology.

"The moral clarity of World War II, while nice at the time, was unhelpful in the long run because it led us to the comfortable but inaccurate thought that most wars have a similar moral clarity," Widmer says.

The World War II paradigm morphed seamlessly into the Cold War. It was again a fight between good and evil fought on the battlefield of ideas. Capitalism vs. Communism. Freedom vs. Slavery. Democracy vs. Totalitarianism. Take your pick. The line was drawn. It was light vs. darkness. The Russian people were not our enemy, they were fellow victims of communism.

"At the heart of this is, I think, the fact that World War II appeals to a more universalist view of the world," says David Hogan, a historian at the U.S. Army Center of Military History. "It is a view that says we are all really the same, deep down, that there are certain standards in the world, standards of good and evil, that we need to uphold.

"What that says is that we can go into Germany and Japan and appeal to their better instincts and institute democracy and in the end, they will love us for it," says Hogan, who is a lecturer in the honors program at the University of Maryland, College Park.

This vision survived the Korean War, despite blunders that led the U.S. citizenry to tire of the fight, as it was an obvious incursion by the communist North into the capitalist South. But the paradigm bogged down in Vietnam.

It began with the World War II model - stop them early in a small fight or we will be in a big war. The political class of the country was dominated by World War II veterans and the lesson they remembered was that Adolf Hitler should never have been allowed to take the Sudetenland, that part of Czechoslovakia that Germany was given in a 1938 conference in Munich, leading British Prime Minister Neville Chamberlain to brag that he had achieved "peace in our time." Of course, the opposite was the case. If, the theory goes, the Western powers had just stood up to Hitler then and there, World War II would have been avoided.

But, as the fighting in Vietnam dragged on, the World War II-era black-vs.-white picture began to develop shades of gray. Was Ho Chi Minh an evil communist or a nationalist fighting the continuation of rule by outside powers, the French, the Japanese, the United States? Was it a fight against invading armies from the north, or against rebels who lived in the south? And even if it was armies from the north, didn't they have more right to be there than troops from the United States? And what about those canceled 1956 elections? Would the domino theory really come to pass, would other Southeast Asian countries really fall to the communists if the north prevailed in Vietnam? And so on.

Eventually, Vietnam came to be seen as a mistake by a majority of Americans. The World War II-Cold War paradigm was in trouble. Now, foreign wars were complex events, difficult to read, full of pitfalls. Caution was the new order of the day. There were quick hits, such as Grenada and Panama, and proxy wars, such as Afghanistan. And there were all-out retreats, such as Beirut, Lebanon, after the bombing of a Marine barracks. And there were negotiations, not invasions, as in Iran during the hostage crisis.

"Vietnam lends itself to a more relativistic view of the world," Hogan says. "This says that, yes, we are different and there are a lot of differences we can't understand. It makes us ask, who are we to determine what is right or wrong in the world, what is good or evil? It gets away from the crusading mentality."

In 1991, when Iraq under Saddam Hussein invaded Kuwait, the presence of the two paradigms was apparent. The president was George Bush, a veteran of World War II. For him, it was clear. Kuwait was something like the Sudetenland. To let Hussein have Kuwait would only invite him to further mischief, just as it did for Hitler in 1938.

But for those with the Vietnam paradigm at the forefront, war with Iraq was a tricky prospect, a fight on unfamiliar terrain and among unfamiliar cultures that could ensnare American troops and foreign policy for years, maybe decades, to come. Perhaps negotiations would be a better idea.

In the end, Bush played it down the middle, freeing Kuwait from Iraqi occupation, but stopping there, not heading into that country to topple the dictator as American and Soviet troops did in Germany in World War II. But the first Gulf War marked the return of the World War II paradigm to dominance in the American political scene.

Soon, many were saying that Vietnam was not a mistake, it was the right thing to do. And the United States would have won had not the politicians in Washington lost their nerve, the domestic equivalent of blaming bad ideology.

Also important was the fact that two years before that first Gulf War, the Cold War had ended with the collapse of the Berlin Wall. "I think victory in the Cold War revived a sense of American exceptionalism," Hogan says. "In the end, America figured it out and emerged victorious in the big global struggle.

"In that view, Vietnam, instead of being a major wake-up call, becomes a minor setback," he says.

When the attacks came on Sept. 11, they fit perfectly into the World War II model, which was then being lionized in 50th- and 60th-anniversary celebrations, in books like Tom Brokaw's The Greatest Generation, published in 1998, and in movies like Stephen Spielberg's Saving Private Ryan, which came out the same year.

The World Trade Center and Pentagon attacks were immediately likened to Pearl Harbor. The United States was clearly an innocent victim, as were the 3,000 killed that day. The battle was one of ideas, of freedom vs. tyranny and intolerance. There was, as in World War II, no doubt who was right and who was wrong.

That is a very seductive model that fit the facts of that day quite nicely. But it has been clouded by ensuing events, specifically by the invasion and occupation of Iraq. President Bush went into that war with World War II images dominant in his rhetoric. Hussein was the Hitler figure. The Iraqi people were not our enemy, just their leaders with their twisted ideology. Remove them, as we did Hitler and Japanese Premier Hideki Tojo and Italian dictator Benito Mussolini, and freedom will flourish, as it does in Germany and Japan and Italy.

But events of the ensuing years have made the new dominant paradigm that of Vietnam. Once again, the United States was lured into a complex quagmire by the illusion of fighting pure evil.

Parry-Giles says that the right model for the war on terror might be the Cold War. "I think there is a great parallel between the Cold War and what is going on now," she says, pointing out that this will be a long struggle with periods of war and peace.

"A lot of people argue that war and militarism have become a large part of the United States' identity, especially in the 20th century," Parry-Giles says. "It is part of our public face to the world, but couched in benevolent terms, as in most cases war is framed as helping out those who can't help themselves."

Politically, the World War II model is very appealing. Who does not like to be told that they are good and are fighting evil? And no one has any doubt that there was evil behind the Sept. 11 attacks. So, few politicians will totally abandon that.

Some will keep it at the forefront, saying that no matter how or why we got into Iraq, we are now fighting the type of people who were responsible for Sept. 11 and that fight must be won. And, maybe, when it's won there, it must be won in Iran.

Others will fudge it, saying that the evil we saw on Sept. 11, 2001, must be fought -the World War II model - but that that is not what is taking place in Iraq. Instead, they will conjure up the Vietnam model, characterizing Iraq as a fight that is actually helping those on the side of evil by damaging our reputation in the world and aiding recruiting by groups such as al-Qaida.

So the country will, as F. Scott Fitzgerald once wrote, be borne back ceaselessly into the past, re-fighting the wars of decades ago as we stumble into an uncertain future.

michael.hill@baltsun.com