The ongoing theme of this column will be the gap between the ideals of American foreign policy and the messy realities of American involvement in the world. That a gap exists is obvious to anyone who has studied history or, for that matter, ever watched the news. But the forces that create it are more interesting than most people assume, and more fundamental than is true in many other countries.

Are Americans hypocrites when they extol democracy but prop up dictators? When they can’t stand a communist ruler in Cuba but raise toasts to communist rulers in Beijing? When they send troops to depose a tyrant in Iraq but plead helplessness to intervene against tyrants and genocide in a dozen other less strategically placed countries?

Of course they are—as is obvious to many Americans and to most people outside the country. But that’s hardly a revelation. Any country will give primacy to its national interest, even those small, social-democratic states that define national interest as setting a moral example for others. What makes the United States unusual is the built-in tension—the inescapable hypocrisy—in its approach to the world. China’s foreign policy may be harsh but is rarely hypocritical. It says it will look out for its own commercial and strategic interests and minimise other involvement, and that is what it does. American leaders and diplomats are constantly saying one thing and doing another; and they are bound to keep behaving that way.

The tension between principle and practicality has been present since even before the North American colonies had formed a United States. In 1776, the Declaration of Independence was addressed to a worldwide audience and proclaimed the universal rights of mankind. Twenty years later, as he prepared to leave office, George Washington issued his famous warning against entangling the nascent American “peace and prosperity in the toils of European”—that is foreign—“ambition, rivalship, interest, humour, or caprice.”

In that 20-year cycle is the story of American policy, repeated by the 43 presidents who have come after Washington. Whenever one of them has become too practical minded and overtly motivated by the coarsest kind of national interest, his successor has declared the need to lift America’s sights, restore the nation’s vision, and resume America’s ‘real’ place and beacon of liberty to the world. And whenever a president has become too high minded, theoretical and indifferent to the practicalities of military and economic competition, his successor has promised a return to common sense, hard-headed realism and a determination to fight hard for tangible American welfare rather than airy international goals. The American public wants it both ways—to be admired for its principles, and to be feared and powerful and rich. Without an ideal to stand for, America does not feel like itself. With too many ideals, it feels naive.

Thus the constant alternation. After Richard Nixon proved too crass even to stay in office, the public embraced the overtly pious Jimmy Carter. In retrospect he’s seen as a failure; but at the time, during his rise (I was working for him, as a speechwriter), his patent idealism was the basis of his appeal. After Carter appeared to be overwhelmed by the avalanche of problems of the late 1970s—OPEC, the Ayatollah in Iran, the Soviets in Afghanistan, a prime interest rate of 21 per cent—the public turned to Ronald Reagan with his promise to stop the theorising and make America strong and proud again. With unglamorous practicality, George H.W. Bush put together the vast anti-Iraq coalition of the first Gulf War. He was pushed from office by the then-idealistic seeming and vigorous young challenger Bill Clinton, who blasted Bush for betraying American values by consorting with the “butchers of Beijing” after their crackdown in Tiananmen Square. As a candidate in 2000, a plain-spoken (to put it politely) George W. Bush mocked Al Gore for his high-mindedness about international cooperation on climate change and similar issues. As a re-elected president in 2005, Bush struck an idealistic note that exceeded in sweep anything Jimmy Carter or even Woodrow Wilson had ever said. He proclaimed in his second inaugural address that the tawdry business of balancing principle against practicality was at an end, since “America’s vital interests and our deepest beliefs are now one.” Thus the United States could undertake a policy of “ending tyranny in the world.”

In its doomed ambition, Bush’s speech was practically an invitation to charges of hypocrisy. How did the latest scandal of the Karzai government reflect America’s deepest beliefs? What about Saudi beheadings and strictures on women under religious law? But this was merely an extreme instance of the more general problem: Americans wanting to think well of themselves for their idealism, but also wanting to get all the practical advantages they can. This is the tension to be explored in upcoming columns: about America’s evolving policies in China, in the Middle East, through the former Soviet empire, and elsewhere.

A parallel question is whether another route might be available: instead of the repeated swings back and forth, a more consistent and sustainable policy that encompassed both parts of these contending national impulses. For all his reputation as a moraliser, Jimmy Carter made a serious attempt to describe such a policy. In a speech at Notre Dame in 1977 that was his major statement as president on human rights, Carter said, in contrast to G.W. Bush, “We live in a world that is imperfect, and which will always be imperfect.” Yet despite the certainty of imperfection and likely failure, he said, it was important to press on: “It is a mistake to undervalue the power of words, and of the ideas that words embody.”

If such rhetoric sounds strangely contemporary, it is because it resembles the major speeches of Barack Obama. In his most influential and carefully analysed addresses—about race in America, when running for office, and about relations with the Islamic world and the potential for nuclear disarmament, in his time as president—Obama has presented a strikingly modest form of idealism. He is aware of obstacles and the tragedies of human nature. Yet he has argued for slow but continued steps ahead. We’ll see how long he can sustain that vision, and whether it can reduce the ideals/reality gap.