That was far below what turned out to be an average annual increase of 6.5 percent in the eight years of the Clinton administration, when tax rates at the high end of the income ladder were raised.
Since 2001, the annual per capita revenue from income taxes fell 1 percent under President Bush even though tax collections picked up sharply starting in 2005. The budget surplus Mr. Bush inherited turned into a deficit.
“If you are cutting taxes without offsetting the cuts through reductions in spending, then all you are doing is increasing the debt and postponing the taxes,” said Jason Furman, director of the Hamilton Project at the Brookings Institution, and also a policy adviser to the Democratic presidential candidates.
Circumstances vary across the decades, of course, and it is difficult to sort out all the various influences on the economy and tax revenues. But when Mr. Reagan and his supply-side advisers first pushed through a range of tax cuts, they applied their logic to the broad mass of taxpaying workers. They argued that the incentive from lower rates on additional increments of income would prompt people to work that extra day or get more education to qualify for a better job.
Similarly, a spouse might take a new job, encouraged to do so by the promise of more take-home pay. The family’s taxable income, and the nation’s, would grow, the theory suggested, producing more tax revenue even at the lower rate.
That was before so much more of the national income flowed to upper-end households, and before the actual tax collections of the last three decades undercut the supply-side argument. Now the supply-siders single out the wealthiest Americans and argue that because they have so many ways to shelter their money from taxes, the incentive to declare more taxable income is much greater when tax rates are lowered than it is for the less well-to-do.
“The supply-side argument these days really applies to upper-income people,” said Robert M. Solow, a Nobel laureate in economics who served in the Kennedy administration. “They are portrayed as the golden geese, and you don’t want to discourage them from laying their eggs.”
By contrast, Mr. Solow says, “the Democrats are convinced they’ll lay their eggs anyway, without tax cuts as an incentive.”
Senators Hillary Rodham Clinton and Barack Obama, contending for the Democratic presidential nomination, reflect that point of view. They say that they have no intention of undoing the Bush tax cuts on families earning less than $250,000 a year. Married couples with incomes above that level, however, would once again be taxed by either candidate at up to 39.6 percent — the top rate reached during Bill Clinton’s presidency.
President Bush pushed through legislation in 2003 that cut the top rate to 35 percent, but only until 2011. Senator McCain wants to extend the 35 percent rate indefinitely and his camp increasingly cites as justification the supply-side effect on upper-income families.
Having once voted against the Bush cuts, Mr. McCain has reversed position and now has even enlisted Mr. Laffer as a special adviser. “McCain is on the right track,” Mr. Laffer said.
While Mr. Laffer insists that tax revenue will rise when tax rates are cut, other supply-siders are less categorical. Martin Feldstein, a Harvard economist who was the first chairman of President Reagan’s Council of Economic Advisers and now supports Senator McCain, estimates that a 10 percent tax cut would in fact reduce tax revenue — but only by 3 to 5 percent.
“It is not that you get more revenue by lowering tax rates, it is that you don’t lose as much,” he said.
Not since Mr. Reagan ran in 1980 have supply-side tax cuts been so central a campaign issue. George H. W. Bush and Bill Clinton each ended up raising taxes, ignoring the supply-side thesis, which the elder Mr. Bush once called “voodoo economics.”