Washington — ''There is strong evidence that a recovery is coming, but no clear evidence that it has begun.'' Thus Martin S. Feldstein describes the economic analysis - ''quite realistic, no wishful thinking'' - that went into shaping the fiscal 1984 budget President Reagan has just sent up to Congress.
Had the recovery clearly begun a month or two ago, the White House might have projected a higher growth rate for the US economy in calendar 1983 than the 3.1 percent the budget specifies.
But, says Dr. Feldstein, chairman of the Council of Economic Advisers, ''We could not be sure of that.''
Thus the President and his aides chose to be ''cautious, prudent,'' Feldstein says, and present a budget that would be ''credible for serious budget work'' in Congress and credible to financial markets.
''If January turns out to have marked the beginning of recovery,'' says Feldstein, ''I would not be at all surprised to see 5 percent growth for 1983.''
Economists in and out of government cite factors that herald imminent recovery, including the broadly based rise in December's index of leading economic indicators.
This rise, says Barry P. Bosworth of the Brookings Institution, ''was pretty solidly based, indicating that early this year there should be a pickup in production and perhaps hiring.''
One factor is what Mr. Bosworth calls an ''inventory workoff.'' Merchants, having pretty well cleared their shelves of stock, must reorder goods to replenish supplies. This means increased production.
Bosworth also cites ''a sharp reduction in the number of people filing initial claims for unemployment benefits.'' In addition, he says, ''the Federal Reserve is not fighting the recovery now.''
The Fed, after long months of combating inflation by restricting credit, now is allowing more loan money to flow through the banking system.
But, cautions Bosworth, ''the leading economic indicators do not tell us anything about the strength of the recovery.'' He and other analysts note several potential drags on the pace of recovery:
* Retail sales - the main engine of the economy - remain weak, though Americans in general appear to be poised to buy, once their confidence in the future returns.
* Business investment in new plant and equipment - another spur to the economy - is expected to be low this year, partly because existing factory capacity is not fully utilized.
* Real interest rates remain high.
* US export sales, accounting for millions of American jobs, are slack, due mainly to the high value of the dollar compared with foreign currencies.
There seems to be, as Congress, economists, and the public settle down to analyze President Reagan's 1984 budget, general agreement on two aspects of the document:
* The economic assumptions on which it is based are realistic.
* Economic recovery will start soon, but is likely to be weaker in the beginning than other postwar recoveries.
The President's new budget calls for record outlays of $848.5 billion and a deficit of $188.8 billion. Economic growth in calendar 1983 will be 3.1 percent, consumer prices will rise by 5 percent, and unemployment will average 10.7 percent, declining to 10.4 percent by the end of the year.
The budget embodies an overall spending freeze, in the sense that the growth of federal outlays is held to the rate of inflation, or 5 percent.
Within that overall freeze, wide variations exist. Defense spending will grow at about 10 percent real rate, while nondefense programs, taken as a whole, will be cut by 3 percent - assuming Congress goes along with Mr. Reagan's spending priorities.
''All of these (budget) efforts,'' says Treasury Secretary Donald T. Regan, ''are designed to reduce deficits from nearly 7 percent of GNP (gross national product) today to 2.4 percent by 1988, putting the budget on a path consistent with sustained economic recovery.''
Success in this effort, according to the White House blueprint, requires both economic recovery and passage by Congress of everything for which the President has asked.
The budget describes a recovery lasting until fiscal 1988 - featuring 4 percent real growth for six years.
''Most recoveries since World War II,'' acknowledges Feldstein, ''did not last as long as projected here. The real problem is to have this kind of growth, over so long a period, without renewed inflation.''