When Warren Buffett speaks, people listen. When Buffett, William H. Gates Sr. and more than 100 other affluent Americans speak out in support of a tax aimed at the wealthy, perhaps we should all listen.

And speak out they did. Last week they urged Congress not to repeal the estate tax.

Buffett is an Omaha investor and, according to Forbes magazine, the fourth richest American. Gates, wealthy in his own right, is best known as the father of Microsoft founder Bill Gates. Among those joining them were billionaire financier George Soros and some Rockefellers.

These are people who know something about money.

Gates is organizing a petition drive aimed at persuading Congress to keep the estate tax. According to the petition, the revenue now raised by it would "inevitably be made up either by increasing taxes on those less able to pay or by cutting Social Security."

The first $675,000 of an individual’s estate is now exempt from what critics call the "death tax." The exemption is $1 million for farms and family businesses and is scheduled to increase to $1 million for individuals by 2006. Larger amounts are taxed at rates ranging from 37 percent to 55 percent on sums greater than $3 million.

Fewer than 2 percent of all estates are taxed. Almost half the tax collected comes from the heirs of the roughly 4,000 people who die every year leaving estates of $5 million or more.

Even so, President Bush’s tax plan estimates that doing away with the estate tax would cost $236 billion over the next 10 years. Critics say that figure is too low.

Those who seek to avoid the tax often do so now by giving to charity. Without that incentive giving will suffer.

Ending the estate tax, says Gates’ petition, "would have a devastating effect on public charities."

Buffett did not sign the petition – he thinks it does not do enough to explain how the estate tax promotes economic growth by rewarding merit.

"Without the estate tax," Buffett says, "you in effect have an aristocracy of wealth, which means you pass down the ability to command the resources of the nation based on heredity rather than merit."

Buffett is right. More can be done to help small businesses and farms, but the answer is not to foster a permanent ruling class.