New York:
More than three dozen billionaires, including well-known philanthropists like David Rockefeller and Mayor Michael R. Bloomberg of New York and less familiar big donors like Lorry I. Lokey, founder of Business Wire, have promised at least half of their fortunes to charity in response to calls from Bill and Melinda Gates and Warren Buffett.
"During even the Depression's worst years, my parents gave money -- about 8 percent of their annual income of $2,200," Mr. Lokey wrote in a letter posted on the Web site of the Giving Pledge, the program that the Gateses and Mr. Buffett started in June to encourage other wealthy people to give. "I remember saying to my mother that we can't afford that. But she said we have to share with others. I learned from that to share."
The pledge has been a matter of some debate in philanthropic and nonprofit circles, with some experts dismissing it as a publicity stunt and others predicting that it would produce a flood of new money to support nonprofit groups.
The program has predicted that it will draw $600 billion into philanthropy -- or about twice the estimated total amount given by Americans last year -- although in a telephone interview on Wednesday, Mr. Buffett acknowledged that some of the money would have been donated anyway.
"This group was going to give a lot of money to charity, but some will increase their giving as a result of the pledge, and a few would not have gotten to the 50 percent," he said. "It's not like all or half of the money represented is added money, but some of it is added."
He said he thought the real value of the pledge was found in the example that it set and in the sentiments expressed in the letters posted on the Web site.
Perhaps the biggest surprise on the list was Larry Ellison, the founder of Oracle, who became the bad boy of philanthropy after he infamously withdrew a $115 million gift from Harvard University in protest over the resignation of Lawrence H. Summers, who was then its president.
In a brief note addressed "To Whom It May Concern," Mr. Ellison revealed that he had already assigned 95 percent of his wealth to a trust and noted that he had already given hundreds of millions of dollars away for medical research and education.
"Until now, I have done this giving quietly -- because I have long believed that charitable giving is a personal and private matter," Mr. Ellison wrote. "So why am I going public now? Warren Buffett personally asked me to write this letter because he said I would be 'setting an example' and 'influencing others' to give. I hope he's right."
Mr. Buffett said that the number of people who had agreed to sign on was at the high end of his expectations. He and Mr. and Mrs. Gates have made between 70 and 80 calls to encourage participation since the program started in June, contacting people they knew well and some they knew only casually or not at all. "If you told me we'd have 10 percent of the Forbes list after three of us just making calls, I wouldn't have believed you," Mr. Buffett said, referring to the annual list in Forbes Magazine of the country's wealthiest denizens.
He said some people who did not agree to sign the pledge were planning to give away the majority of their wealth but did not want to draw attention to those plans, because they were concerned about attracting an onslaught of supplicants or because they believed that publicity for giving dilutes its value.
Some went on "a tirade" about the government and rising taxes, Mr. Buffett said -- declining, of course, to name them. "A few got into that, and there are some that have a dynastic attitude toward wealth," he said. "That tends to be the case where they themselves inherited this money and maybe feel some sort of intergenerational compact about it."