As prosperous superpower, what does US owe the world?

Delivering a commencement address at Boston University, Afghan President Hamid Karzai said this about US involvement with his country before 9/11: "The United States and other countries that had the power, and hence the responsibility, did not see it compatible with their national interests to address the plight of the Afghan people then."

It was that little "hence" that gave me pause. If one is powerful enough to help, is one morally obliged to help?

"With great power comes great responsibility" is a classic cliche, indeed the very slogan of Tobey Maguire's "Spider-Man."

But great responsibility also brings with it great resentment on the part of those for whom one is responsible, which is rational and inevitable.

The fact that you are responsible for your children, for example, is a justification for your power over them. But they cannot throw off your authority - as eventually they must - without throwing off your responsibility for them, including the fact that you pay for their car insurance or their groceries.

This is one reason why so much of the world has a deeply ambivalent relationship with the United States at the moment. They need us in order to rise out of poverty. But if they enlist our aid to rise out of poverty, their gratitude is a form of dependence and a source of resentment.

As a general matter, the question of the connection of power to responsibility is something we face all the time, and it is extraordinarily complex.

Does being wealthy make acts of charity a moral obligation? Does ability to offer a better life mean the United States should throw open its borders to immigrants? Does the fact that I can afford to contribute money to my daughter's school entail my contributing to schools that serve the poor?

In fact, some school districts will not permit you to contribute to your child's school because funds must be allocated according to certain formulas.

This immediately reveals certain complexities: Over whom is my power, and to whom is my responsibility? And whatever someone's conception of my responsibilities, should I be forced to discharge them?

The connection of power to responsibility is a theme of international diplomacy, of national policy, of community formation, and of personal relationships. It's a theme that cries out for a general and systematic treatment. At the least, we might generate some observations.

"The power, and hence the responsibility": One problem is that the "hence" runs the other way as well. If you have responsibility for someone, it follows that you have power over them.

In the context of foreign affairs, charity is a traditional form of oppression. Even at its best, as in the British Empire's control of Afghanistan, for example, colonialism was justified by the responsibility conferred by wealth and power - the "white man's burden," as the great British imperialist Rudyard Kiplingput it. And by many measures, one supposes that life in Afghanistan improved under British rule.

In a way, the transaction is less damaging if it's less straightforwardly charitable. Mr. Karzai seems to understand that as well, because immediately after urging purity of motivation - urging Boston University's graduates to relieve poverty only for the sake of the poor - he argued that world poverty undermines US prosperity and security.

Sadly, it is not perfectly clear that US prosperity does not depend on world poverty.

And I'm not certain that a more prosperous North Korea or Syria would improve our security, either.

In fact, nothing about this whole issue - either specifically as it relates to Afghanistan policy or as it plays out in the lives of all of us - is perfectly clear. It is an abysmal thought that charity is wrong and that you should never ease people's suffering lest you render them dependent.

But whose suffering are you obliged to ease? And how? And for how long? And why, really, are you doing it - for them or for yourself? Are you expressing your generosity or your authority?

The difficulty is that these things are inextricable.

• Crispin Sartwell teaches political philosophy at Dickinson College in Carlisle, Pa. © 2005 Los Angeles Times