Toby Ord counts himself among the world's wealthiest men, but don't be surprised if you have never heard of him.

He makes $52,000 a year as a philosophy researcher at the University of Oxford, so he is no tycoon. Yet that relatively modest salary places him in the top 1 percent of earners on a planet where 800 million people go to bed hungry every night.

It is a troubling income bracket for a man who spends his days thinking about ethics.

So a little over a year ago, Mr. Ord founded Giving What We Can, a philanthropic collective with two primary rules to guide its largely academic membership: Give generously, and give effectively.

"I'm not a natural leader by any means," says Mr. Ord, a 31-year-old Australian who investigates moral questions at Oxford's Balliol College. "But no one else was going to do this, so I picked it up and ran with it."

He quickly recruited some big names for the group, people like Peter Singer, the Princeton University bioethicist whose book The Life You Can Save is a call to arms for the global antipoverty movement, and Thomas Pogge, the Yale University political philosopher whose World Poverty and Human Rights argues that the West's trade policies make it complicit in the extreme poverty that haunts the developing world.

The collective's 80 members promise to donate at least 10 percent of their annual pretax income to charities that fight global poverty. Together they have pledged more than $25-million.

Mr. Ord believes that most people, with high goals and a little discipline, find they can afford to donate more than they otherwise would—in his case, much more. He has promised to donate all of his earnings above $28,000 a year after taxes. Over the course of his working life, he expects to give away about $1.6-million, by his estimate about two-thirds of all the money he'll ever make.

When Giving What We Can went public, in November 2009, British newspapers cast Mr. Ord as the embodiment of its austere principles. Articles described how he and his physician wife, Bernadette Young, occupied a sparsely furnished college rental, eschewed such luxuries as fashionable clothes, a television, and a car, and limited their dining out to coffee once or twice a week and dinner once every other week. In photos, Mr. Ord is the poster child of frugal living, his clothes hanging loosely from his lean frame.

The story rubbed some readers the wrong way, drawing speculation in the posted comments that Mr. Ord and Ms. Young were either naïve or anticipated a large inheritance. (They don't.)

"What a pair of freaks," wrote a reader named Penelope last year in the Daily Mail. Another reader, commenting under the name "Shoe Addict," wrote, "It is much easier to adopt these kind of ideals if you are a childless couple and only have yourselves to worry about."

Mr. Ord says such comments didn't surprise him, considering reporters' overdrawn caricatures of his life. "They typically want me to say that it's really arduous, that I give up all these things. I don't think that's particularly true."

For starters, he was very recently a graduate student, living on far less than he does today, so he doesn't miss the money that now goes to charity. (Making the same point, graduate students at Rutgers University recently founded the first American chapter of Giving What We Can.)

In addition, Ms. Young's personal-allowance ceiling is higher than her husband's: She donates everything above about $40,000, meaning the couple still has more to spend than most British households gross. The two don't spend frivolously, but neither are they particularly miserly. Mr. Ord is happy not to have the hassle of keeping a car running, and he doesn't miss television. "A lot of young people watch DVD's on their computers," he points out.

Ms. Young and Mr. Ord take advantage of Oxford's cultural offerings. They enjoy reading books and spending time with each other. They sock away savings for the house they will one day buy, and they travel: to England's Lake District, to continental Europe, and, every other year, back to their native Australia.

"Don't they look lovely," clucked another of the commenters on the Daily Mail's profile of the couple. "Wouldn't want to sit in a pub with them telling how wonderful they are."

Luxury vs. Lives

The intellectual origins of Mr. Ord's group date to an essay that Mr. Singer, the bioethicist, wrote 40 years ago for the first issue of the journal Philosophy and Public Affairs. "It is morally indefensible to live in abundance while others starve," he says. In that 1972 paper, "Famine, Affluence, and Morality," he likened the West's ethical obligation to feed Bangladesh to a neighbor's responsibility to save a child from drowning in a shallow pool of water.

Six years ago, Mr. Ord cited the same metaphor in his own paper on the topic: "Ought I to forgo some luxury whenever [doing so] can thereby enable someone else's life to be saved?" he wrote. The answer, he concluded, was yes, and he began sketching out a proposal for Giving What We Can.

Key to his project was making sure members' generosity would make a real difference.

The group's Web site steers donors to cost-effective charities like Deworm the World, which focuses on neglected tropical diseases in 26 developing countries. In India, for example, a child can be treated for parasites for as little as 12 cents a dose. Mr. Ord points to a calculator on his group's Web site showing that his own pledge could save as many as 2,100 lives, because money simply goes further in the developing world.

"Most people just aren't aware of what the disparity is in how effectively you can help by giving to people far away," he says. "Where you give can be more important than whether you give."

For as little as $3.41, less than the price of a pint, a donor can save one year of a person's healthy life in India, Mr. Ord says. But he knows the flip side, too, recalling a day early on when he became paralyzed with indecision over the seemingly mundane choice of whether to spend a few pennies extra for a more desirable breakfast cereal.

"To try to approach every single action in that way, it's not sensible," he says. "It requires a lot more mental energy."

Nowadays he assesses the impact of his donations annually and weighs whether he should have given more. Giving What We Can clearly has an approach different from those of many other antipoverty groups. Its Web site carries no photos of fly-covered children with distended stomachs. Guilt-inducing statistics are few. Instead it has ample links to authoritative resources like the United Nations' Human Development Reports, a straightforward series of responses to eight "persistent myths" about aid, and a list of U.N. estimates on what it would cost to provide basic education for all ($6-billion), clean water ($9-billion), and basic health care ($13-billion).

Thomas Pogge, the Yale philosopher, has this to say: "The world poverty problem is much, much larger than you think, in human terms. The suffering is much greater." But "the economic magnitude of the problem is much, much smaller than anybody believes."

The poorer 50 percent of the world's population earns less than 3 percent of global household income, he says. "If they had 5 percent instead of 3, poverty would be history."

Mr. Pogge says he donates as much as $40,000 a year to charities in the developing world. Lately he's been experimenting with direct giving, a personalized approach that could serve as a philanthropic model for other scholars with international contacts. In one situation, he underwrote the purchase of 13 carabaos—a type of water buffalo—to help the Iraya Mangyan people, on the Philippine island of Mindoro, become self-sufficient. Fatima Alvarez Castillo, a professor of politics and research at the University of the Philippines at Manila, had been studying the islanders, who told her they needed the animals to pull their plows and haul agricultural goods to market. Aside from the fatal illness of one of the animals, Mr. Pogge says, the project has been a success.

"The economic and socials benefits have been positive," he says. "The people feel great pride."

Among Giving What We Can's other members are Michael Kremer and Rachel Glennerster, influential development economists at Harvard University and the Massachusetts Institute of Technology, respectively, who direct research that measures with increasing accuracy the impact of health-care treatments in the developing world.

The collective has plenty of company. In addition to myriad faith-based groups, student members of the Millennium Campus Network work in support of the United Nations' effort to sharply reduce global poverty by 2015. Fifty-eight billionaires have joined the Giving Pledge, an exclusive club whose members promise to give at least 50 percent of their fortunes to charities (but not necessarily those that fight poverty).

And Ann M. Svennungsen, a former president of Texas Lutheran University, is working with the donor network Bolder Giving, to recruit charter members for the Presidents' Pledge, a new group that will comprise college presidents who promise to donate at least 5 percent of their own income to mitigate global poverty. Ms. Svennungsen, who plans to identify the presidents in this group in the spring, is shooting for 200 members.

When she does, she'll probably face criticisms similar to those Mr. Ord has heard, like this one from a Daily Mail commenter: "The gesture would mean so much more if you didn't crow about it."

Peter Singer has heard that tune before. "People like to be cynical about others who are doing something good," he says, "because it challenges them to do something themselves."