In a recent University of Chicago survey of 38 prominent economists across the ideological spectrum, only one said the proposed tax cuts would yield substantial economic growth. Unanimously, the economists said the tax cuts would add to the long-term federal debt burden, now estimated at more than $20 trillion.
If the package does have a guiding philosophy, it is a return to trickle-down economics, an enduring story line in which the wealthy are supposed to spend and invest their tax breaks, creating jobs and commercial opportunities for everyone else.
As President Ronald Reagan slashed taxes in the 1980s, he argued that citizens, not bureaucrats, should decide how to spend their money. President George W. Bush bestowed enormous tax cuts on the affluent.
But the trickle-down story has yet to achieve its promised happy ending. Only the beginning reliably transpires, the part where wealthy people get relief. The spoils of resulting economic growth have largely been monopolized by those with the highest incomes. Pay for most American workers has been stagnant since the mid-1970s, after the rising costs of housing, health care and other basics are factored in.
Nonetheless, Republicans are staging a trickle-down revival.
"Either it's a religious belief, a belief where no amount of evidence would change that, or they are using the argument cynically and they just want more money for themselves," the economist Joseph E. Stiglitz, a Nobel laureate, said.
Mr. Stiglitz has long warned of the perils of growing inequality while deriding tax-cutting inclinations. Yet even those who have favored lighter tax burdens are critical of the current proposals.
In the late 1970s, Bruce Bartlett developed what would become the locus of the Reagan tax cuts while working for Representative Jack Kemp, a conservative Republican from New York. Those cuts helped cushion the pain from sharp increases in interest rates by the Federal Reserve, Mr. Bartlett maintains. But Reagan was lowering the highest tax rate on individuals from 70 percent down to 28 percent by 1986.
"What they have here is a big tax cut for the rich paid for with random increases in taxes for various constituencies," Mr. Bartlett said. "It's ridiculous. And it's telling that they are ramming this through without any debate. All of the empirical evidence goes against the tax cut."
The meat of the package is a permanent lowering of the corporate tax rate, to 20 percent from 35 percent, which business leaders have long wanted. Proponents assert that this would prompt multinational companies to expand operations in the United States.
"We've been bleeding corporate headquarters and production for a long time," said Douglas Holtz-Eakin, a former director of the Congressional Budget Office and now president of the American Action Forum, a nonprofit that promotes smaller government.
But recent history suggests that when corporations get tax relief, they find abundant uses for money that do not involve paying higher wages. They give dividends to shareholders and stock options to executives. They stash earnings in tax havens.
In 2004, Congress invited American corporations to bring home overseas earnings at a sharply reduced rate, pitching it as a means of bolstering investment. But the corporations spent as much as 90 percent of their windfall buying back their shares, according to Bureau of Economic Analysis research.
If Congress bestows fresh relief on major businesses, signs suggest a similar result. Many companies are enjoying record profits. Those in the Fortune 500 had $2.6 trillion salted away overseas as of last year.
"In our boardroom, the number-one thing we're talking about is not taxes," said Jeremy Stoppelman, chief executive of Yelp, the online review platform. "Having a strong middle class out there spending money is what's most important for our business."
If the tax bill widens inequality, local communities will likely find themselves with fewer resources to aim at helping struggling people.