They call it American exceptionalism. It holds that America is culturally superior to the rest of the world, a beacon to the rest of the world, and has an evangelical mission to spread American values to the rest of the world.

President Barack Obama and his Republican challenger Mitt Romney paid due lip service to it in the last of this election’s three Presidential debates, the one dedicated to discussion of foreign policy.

Obama said America remains the world’s one indispensible nation. Romney promised to maintain the United States as “the hope of the earth.”

But the interesting thing about the debate was the tacit acknowledgement — more on the part of Obama than Romney, to be sure, but by the challenger too — that the way America projects itself to the world has to change.

The traditional way for America to do that of course, is by force. As the great satirist Tom Lehrer once sang: “When in doubt, send the marines.”

SAUL LOEB/AFP/Getty Images

US President Barack Obama (L) greets Republican presidential candidate Mitt Romney (R) following the third and final presidential debate at Lynn University in Boca Raton, Florida, October 22, 2012.

In fact one of the standout characteristics of American exceptionalism, right from the start, is its martial nature.

Since it became independent — through war — the United States has engaged in literally hundreds of foreign military interventions of one kind or another.

Back in April this year, the web site Upworthy ran a striking graphic representation showing how many years America had been at war and how many at peace since 1776. The score was: war years, 214; peace years, 21.

Very few countries in the world are as devoted to their militaries as the United States. According to World Bank statistics, in 2011, the US spent 4.7 per cent of its GDP on the military. Only Israel, Oman, Iraq, Saudi Arabia and Azerbaijan spent higher proportions of their national incomes on the military. Australia spent 1.9 per cent of its GDP.

American military spending — let’s not call it defence spending, for it is arguable how much of it is truly defensive — accounted for almost 43 per cent of the total for the world in 2010.

It was close to six times the spending of the number two country, China, and well over 10 times that of Russia. Indeed, as Obama pointed out during the debate, the US spends more on its military than the next 10 countries combined.

War is a business for the US. America accounts for more than three-quarters of the global arms trade, and had a record year in 2011, with USD66 billion in sales.

Thus the manufacture and sale of products designed to kill people was one of the few growth industries in the flat US economy.

And that kind of makes the real point here: these days, the things that make the United States exceptional are often not things to be proud of, as Scott Shane pointed out in an opinion piece in The New York Times recently, entitled “The Opiate of Exceptionalism”.

He noted the US ranked 34th out of 35 developed countries in child poverty rates, 28th in the number of four-year-olds attending preschool, 14th on higher education, 49th for infant mortality, and well down the list on measures of social mobility.

There are some areas where America is still a world leader, of course. Economic size, for one, although that won’t be the case for much longer. Also for the number of its people who are imprisoned (grossly disproportionately racial minorities). And gun ownership. And obesity.

So to the debate, which was held, as the moderator — Bob Schieffer, of CBS — pointed out, on the 50th anniversary of President Kennedy’s revelation that soviet missiles being installed in Cuba.

What was interesting about it was how un-bellicose both candidates were, by traditional American standards.

Right off the bat, Romney surveyed the difficulties posed by the Arab spring in the Middle East and north Africa and declared: “We can’t kill our way out of this mess.”

And while the candidates sparred about whose policy was better, and talked tough about trade sanctions and embargoes and supplying weapons to allies and maybe a little targeted killing of al-Qaeda types, they were at pains to eschew any commitment to major force.

No, they both said, we don’t want US forces in Syria. We don’t want war with Iran. We want forces out of Afghanistan by 2014. We must continue to engage with the government of Pakistan, even if we don’t like them.

It was quite extraordinary. There was Mitt Romney, carrier of the Republican torch previously held by George W. Bush and Dick Cheney, conceding you could not defeat extremists by starting wars.

“We don’t want another Iraq,” he said. “We don’t want another Afghanistan. That’s not the right course for us.”

The right course, he suggested, was “to get the Muslim world to be able to reject extremism on its own”.

It was to extend more foreign aid, more trade, to encourage better education, gender equality, the rule of law, the institutions of civil society.

But from a distance, not by invasion.

Of course Romney had to throw a bone to the war buffs who make up such a large part of his party’s base, by saying he would spend more on the military. Now, you might think this a bit crazy. Why increase military spending by another trillion dollars when you already have the biggest armed forces in the world, by far? But if you think that, you’re not a true Republican patriot.

Anyway, the essence of it was that the candidates made debating points, but really the event was an agree-a-thon. On foreign affairs, that is.

The real debate was not about foreign affairs, however. It was about domestic policy, to the point where moderator Schieffer kept having to intervene to pull the candidates back to the supposed focus of the debate.

But they found cunning ways to circumvent him. Obama, for example, began to talk about the futility of US efforts at nation building abroad, and segued into the need for nation building at home.

“And we’ve neglected, for example, developing our own economy, our own energy sectors, our own education system,” he said.

“And it’s very hard for us to project leadership around the world when we’re not doing what we need to do here.”

Romney did likewise, arguing that “for us to be able to promote those principles of peace requires us to be strong, and that begins with a strong economy here at home…”

He cited Iran’s president Mahmoud Ahmadinejad, who “says that our debt makes us not a great country, that’s a frightening thing. The former chief of — chief of the Joints Chief of Staff said that — Admiral Mullen — said that our debt is the biggest national security threat we face.”

There are plenty more examples, but you get the point. Having fought two protracted wars on credit, and having put itself in the poorhouse as a result, America is now tired of foreign adventurism.

And Romney and Obama know that.

This election cycle, for the first time in a very long time, there is no great advantage to be found in the expression of martial sentiment.

It was clearest at the end, as the candidates gave their closing statements.

Obama talked about the economic damage done by Iraq and Afganistan, about the need for a more equal society, for the return of manufacturing jobs, about energy independence, and “nation building here at home”. He did at least talk about the need to provide better care for returning troops, which sort-of related to foreign policy.

Romney didn’t even try to relate his closing remarks to foreign policy, unless you count a vague reference to promoting “principles of peace”. His pitch was about national debt, falling pay, unemployment.

All considered, this was the most inward-looking debate on “foreign policy” I can ever recall.

It was truly a bit of exceptional Americanism.