World poverty and hunger are serious problems and require serious, but also feasible, solutions. Obviously, in addition to encouraging efforts among the poor that could help remedy or mitigate their poverty (for example, birth control information and devices so that poor families don't have more children than they can afford to raise, and job training that prepares people to earn decent wages), we should motivate people who have more than enough to give away more of their excess income (but not all of it) to charities that help the poor.

A wise principle in Jewish law, the religious tradition with which I'm most familiar, states that "a decree may not be imposed on the community unless the majority can bear it." Thus, a person should give at least 10 percent of his or her net income to charity, but not more than 20 percent, lest the giver become poor. Obviously, there are people who can afford to give more than 20 percent and still remain wealthy, but they are the exceptions.

It strikes me as both more moral and more helpful to the hungry to make reasonable demands of people (demands that insist on far higher levels of giving than is the prevailing norm) than it is to make utopian demands that will be ignored--and that will produce some very unpleasant side effects.

Having said that, I think we should thank Professor Singer for prompting people to think about whether they should give more to charities that help the truly needy. I have long been moved by the words of the great Christian thinker C.S. Lewis, who wrote in " Mere Christianity": "If our charities do not at all pinch or hamper us, I should say they are too small. There ought to be things we should like to do and cannot do because our charitable expenditures exclude them."

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Joseph Telushkin, a rabbi and Beliefnet columnist, is the author of 10 books, including "The Book of Jewish Values," just out from Bell Tower/Crown.