Washington — It is out in the open now that President Reagan's top economic aids disagree fundamentally on the impact budget deficits have on interest rates and the economy.
Disagreement, however, will neither serve to bring down interest rates nor shrink the budget shortfall, because Congress and the White House effectively have shelved the issue until after the 1984 election.
''We need a consensus to reduce the deficit,'' says Alice M. Rivlin, former director of the Congressional Budget Office and current director of economic studies at the Brookings Institution. ''The consensus is not there.''
Lack of consensus begins within the President's own team, with Treasury Secretary Donald T. Regan and Martin S. Feldstein, chairman of the Council of Economic Advisers (CEA), asserting opposite views on the link between deficits and interest rates.
The rise in real long-term interest rates, said Dr. Feldstein Wednesday, ''is primarily a reflection of the large deficits in the federal budget that are now expected to persist for years to come.''
Not so, said Mr. Regan the same day. ''A thorough Treasury Department study shows that . . . there exists no necessary cause-effect link between deficits and interest rates.
''Economists who continue to claim that deficits make for high interest rates should climb down from their celestial observatories and acquaint themselves with terrestrial fact.''
A lot of observatories would be deserted if the Treasury chief had his way, because most professional economists - in and out of government - find a direct link between huge deficits and the investment community's reaction to them.
Mr. Regan, however, has the ear that to him counts the most: namely, Mr. Reagan's. In shaping economic policy the President appears to listen more to Regan and White House political aides than he does to Feldstein.
Reagan rejects the tough, potentially unpopular steps that would have to be taken to curb deficits - tax hikes and cuts in defense and entitlement program outlays.
The Treasury secretary tells the President, in effect, that he does not have to worry about deficits becoming a major political problem next year - that, given a robust recovery, interest rates will not soar before the election, nor will private investors be crowded out of the borrowing market.
This begs the issue in Dr. Feldstein's view.
''If no legislative action is taken to alter the status quo,'' he says, ''the budget deficits from 1983 through 1988 will total more than $1,200 billion and will more than double the . . . public debt.''
''To get the public to absorb this debt,'' he adds, ''requires a rise in interest rates, and it is this rise that is reflected in the current high real interest rates.''
Investors, in other words, will agree to buy Treasury notes and bonds in the massive amounts needed to finance the deficit only if they yield high interest. Thirty-year Treasury bonds now carry a 12 percent yield.
Deficits in the past, most economists agree, generally have been associated with recessions or periods of slow growth, when private borrowing was low. Deficits in such cases do not push up interest rates because during a recession, few people are borrowing money to expand or modernize their businesses, build new homes, or buy new cars or appliances.
Now, however, the economy is expanding briskly - a period of ''exuberant growth,'' says Regan - and private-sector demand for capital should pick up. Much of that demand, says the Treasury chief, will be financed from ''internal resources,'' mainly profits. He foresees no credit crunch, at least in the near term.
Economist Charles L. Schultze notes that ''in no previous year of reasonable prosperity has the budget deficit been so large as a percentage of GNP (gross national product) as it will be over the next few years.''
Now 6 percent of the GNP, the deficit is expected to remain at about that level, unless legislative action is taken to shrink the gap between government income and outgo.
Up to 1985, says Dr. Schultze, CEA chairman under President Carter and now with the Brookings Institution, ''real interest rates may not go up. But they may not come down either.''
If they do not decline, he says, some key sectors of the economy - including housing and autos - ''may be in trouble.''