Billionaire Berkshire Hathaway CEO Warren Buffett is once again thrilling the political class by volunteering other people to pay higher taxes. Long-time observers recall his opposition to former President George W. Bush's efforts to reduce the tax rate on dividends. Since Berkshire pays no dividends, Mr. Buffett had little at stake but enjoyed the opportunity to pose as if he were a rich guy eager to cough up more dough to Washington.

In the current debate, President Obama is pushing the "Buffett Rule" to ensure that high-income...