Imagine, for a moment, that you are out walking, and come across a child obviously drowning in a pond.

There is no one else around. You know the pond is not deep enough to drown you and that there are no dangerous things, like alligators, in the water. The only small cost to you is that you might ruin a good pair of shoes, and your clothes will need dry cleaning.

Would it be wrong of you, reflecting on your shoes and clothes, to say "No, I'm not going to go and save that child"?

It is a question philosopher, professor and bioethicist Peter Singer has been putting to his classes at Princeton University and to audiences in other places for years, and which he posed again to several hundred people gathered at the Martha's Vineyard Hebrew Center on Wednesday night.

He did not ask for their responses this time, but he assured his listeners that whenever he has, the overwhelming response is that it would be wrong.

Then he related the hypothetical case to a global question. What is the difference between the person who does not rescue the drowning child and the position of people in affluent nations who allow 27,000 children to die every day in the world from easily preventable causes?

And he answered it. There is no morally relevant difference.

Ten million children die each year from easily preventable causes - lack of sanitation, clean water, treatment for diseases which can be simply cured - a mind-boggling, shamefully large number.

And yet, Mr. Singer said, according to calculations by Columbia University economist Jeffrey Sachs, many of those deaths could be avoided and the one billion poorest people in the world could have their standard of living drastically improved for about $124 billion a year.

Which also seems a stunningly large number, yet it is only a little more than Americans spend on alcohol each year, or about six times the amount spent on bottled water. As a proportion of the income of the 22 wealthy nations that belong to a subcommittee of the Organization for Economic Cooperation and Development, Mr. Singer said, it comes to 60 cents in every $100 earned.

It is also, according to figures provided by Charles Harff, an attorney, businessman, philanthropist and Vineyard summer resident who was the other speaker at the Hebrew Center Summer Institute presentation, less than half the $260 billion Americans gave last year to various philanthropic causes.

And those comparisons make $124 billion - or even several times that amount, assuming the estimate is too low - seem much more achievable.

Yet the two speakers differed. Mr. Singer was there to argue not only that there was not enough philanthropy, but that it was misdirected. The amelioration of the absolute poverty of one billion of the world's people should take precedence over giving to other causes - an overriding obligation, he called it.

"We are in an emergency, where 27,000 children are dying every day of preventable causes. Frankly there seems to be something obscene about being concerned about whether the opera is able to stage lavish productions," Mr. Singer said.

Mr. Harff took what he conceded was a more hard-hearted view.

"While I'm sorry that 27,000 children die every day I think it may be part of the price we pay to preserve what is essentially our civilization," Mr. Harff said. "It is not just the opera, it is the symphonies, the ballets, the universities."

Perhaps they were badly-chosen examples. Elsewhere Mr. Harff argued in terms of more defensible charitable causes closer to home like schools, hospitals and affordable housing.

There were any number of worthy causes, he suggested, and said Mr. Singer was unrealistic in advocating that people on annual incomes of around $40,000 a year should forgo "new cars, new clothes, redecorating their homes, vacations . . . and should devote those resources to alleviating dire poverty in the world." He continued:

"I don't think it's a choice that ought to be suggested to people broadly, because I think it's setting a standard that's unrealistic."

Mr. Harff enumerated past failures. He said aid is too often diverted into the pockets of corrupt officials in the poorest nations.

He also answered some of his own criticisms. He lauded the success of Muhammad Yunus, who won the Nobel Peace Prize last year for founding the Grameen bank to provide micro-loans - average size $123 - to the poor to start small businesses.

"It is estimated by 2015, it will reduce poverty by 50 per cent in Bangladesh," Mr. Harff said.

And he commended the Gates Foundation and billionaire philanthropist Warren Buffet, before ending with a quote from Aristotle: "To give away money is an easy matter in any man's power. But to decide to whom to give it and how large and when and for what purpose and how is neither in every man's power nor an easy matter."

There is simply not enough money to do all Professor Singer advocated.

But Professor Singer marshalled a comprehensive, statistics-based argument.

While it is true Americans give fairly generously to philanthropic causes compared with other developed nations, he noted, they do not give a lot to foreign aid.

"They believe that they give a lot, but that's a myth," he said.

He offered results of several surveys which showed Americans thought between 15 and 20 per cent of the federal budget went to foreign aid. When asked how much they thought should go to foreign aid, the respondents thought it should have been lower - between five and 10 per cent.

They were, he said, "totally deluded." In fact, the United States gives around one per cent.

The interesting thing is, people wanted the government to give more than it actually did. The fact that the country does not, Mr. Singer said, represents a failure of American leadership.

"America's political leaders do not enlighten the public about how little foreign aid is actually being given . . . and do not take a leadership in encouraging more to be given," he said.

As a percentage of the gross national product, government aid equated to just .22 per cent.

Private philanthropy for foreign aid might add fifty per cent to that total, rasing it to one third of one per cent of national earnings.

"That seems to me to be a very stingy figure for a very wealthy nation," he said.

And even that gave an exaggerated picture of America's generosity, for most of the money was given for what he termed geo-political purposes, to middle-income nations, not to help the poorest of the poor.

"Essentially only a quarter of U.S. foreign aid goes to the least developed countries or low income countries," he said.

He compared the amount the United States gave to the poorest nations with the philanthropy of Norway, which gave .94 per cent of gross national product in government aid, although probably a little less than the United States in private philanthropy. All told, Mr. Singer said, Norway gave around one per cent of itsgross national product, or at least three times what the United States did. And twice as much of that money went to the poorest nations.

Mr. Singer was asked about the most effective way to give. He suggested the better administered nongovernment agencies like Oxfam, in which he is active, which bypass corrupt officialdom or inefficient bureaucracy.

He was asked if such charity might not lead to overpopulation and further pressure on the earth's resources and greater future misery. He noted that education, particularly of girls, is the key factor in reducing fertility rates.

He was asked if there was a defined percentage people should give. Mr. Singer said for people who are "reasonably comfortably off" (like most in his audience), the traditional tithe is 10 per cent, while someone earning a million a year could easily give 20 or 30 per cent of it.

And by the end, some in the audience appeared to be fiddling uncomfortably with their jewelry.