Bono is part of the Jubilee 2000 and Netaid campaigns to ease the debt burdens of the world's 40 poorest countries, and he takes international policy decisions very personally. The rock star told Reuters last week that he was "encouraged by the support he had seen in Washington, but remained cautious on whether Congress would respond to the calls to appropriate the necessary funds."

"It's hard to get people in this town to agree on anything and yet people have really come together on this," he told the news agency. "But until I see the $435 million, I'm going to be a bit skeptical."

Bono is only one of many celebrity activists using their fame to bring attention to social problems in recent years, and using social problems to bring attention to themselves. Although showbiz philanthropy is nothing new, it seems few causes célèbres today are not celebrity causes. It's as if every star this side of "Live Aid" has become exclusively, conspicuously associated with one large-scale philanthropic mission or another. Richard Gere's emergence as the Greatest Tibetan Hero comes to mind, as do Sting as Rain Forest Man, Kim Basinger and Alec Baldwin as protectors of animals and Susan Sarandon and Tim Robbins as defenders of Ralph Nader.

The phenomenon is so pervasive as to raise the question, Is large-scale, high-profile social activism a latent trait in every would-be pop star and movie icon? Is the urge to rescue the Earth, the children, the whales, the natural byproduct of selling millions of records or saving the world on-screen year after year? It would appear so, given that the messianic aspirations of the entertainment elite have never been more in evidence.

But not all celebrity philanthropy is equal. Celebrity involvement in a cause can range anywhere from Paul Newman giving more than $100 million to charity to a band agreeing to perform at an event in return for first-class travel, five-star accommodations, fees, perks and publicity. It can mean Michael J. Fox successfully lobbying Congress on behalf of victims of Parkinson's disease or it can mean Barbra Streisand selling charities tickets to her concerts at a discount, so that they can scalp them for the difference.

The Smoking Gun's Celebrity Charity Review reports that Streisand's foundation, whose executive director earns $128,000, gave away $658,159 in grants and contributions in 1997. The band Aerosmith put a tax-deductible $206,500 into the Aerosmith Foundation in 1998, but made donations totaling only $6,150. A 1994 Forbes magazine article told the story of a famous soap opera star who was invited to run a celebrity marathon and "complained bitterly about the size of her free Nike warm-up suit." She apparently told the charity sponsor: "We only do this for the shoes."

But shoes notwithstanding, charity work can also help a rising star gain exposure, help a fading star raise a sagging profile or help a Hollywood supernova get his very own meeting with Congress, an audience with the pope or a televised interview with the president. And while we may never know which celebrities grew up dreaming parallel dreams of stardom and world peace, we do know that celebrity-philanthropy associations are not always spontaneous.

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