Is the American economy going to slip into a recession, a "growth recession" or some other kind of a downturn? At the economic summit in Bonn, President Reagan and his aides had to admit that there have been recent disappointments, but they staunchly denied the likelihood of recession.

Others are hopeful, but not so sanguine. Preston Martin, the vice chairman of the Federal Reserve Board, said in a thoughtful speech the other day that "a growth recession [slow growth, accompanied by rising unemployment] must be considered a real threat.

"In fact, the data currently available suggest that the economy is on the edge between healthy, sustainable growth, and a growth recession. If the Commerce Department is roughly correct in its 1 1/4 percent estimate of first-quarter real GNP [gross national product] growth, the economy has advanced at only about a 2 1/2 percent rate over the past three quarters."

In a subsequent interview, Martin said that he thinks "we have some yellow caution lights flashing." The Fed vice chairman is particularly concerned with the weakness in business fixed investment, which in the first quarter increased at only a 3.5 percent rate compared to a 21.3 percent gain in the second quarter of 1984.

"That's quite a deceleration. So, on the business side, there is some slack, some unused resources out there. And on the consumer side, the burden of debt service for households is getting up there, and one wonders how much longer the consumer can support things," Martin told me.

The essential point is that the economy has been weakening since mid-1984. At the very time in the 1984 presidential campaign that Reagan was extolling the virtues of Reaganomics and assuring the world that the United States could "grow its way out" of the deficit, the bloom was coming off the boom. But the real evidence didn't show up until after the election.

In releasing the annual report of the Joint Economic Committee, Chairman Dave Obey, a Wisconsin Democratic representative, said, "To continue the pretense [that we can grow our way out of the deficit] only adds to the strain already on the economy. This kind of thinking makes our debt go higher and makes the bill much more unmanageable when we decide to pay it."

A critical warning signal is that, despite the upsurge in 1983 and in the first half of 1984, the unemployment rate has been stuck in a 7 to 7.5 percent range, and now threatens to go higher, as Martin suggests, unless the economy gets a lift. Privately, this is what worries Treasury Secretary James A. Baker III and other administration economic officials.

Even with something that falls short of an actual recession -- which is defined as at least six months of an actual decline in real GNP -- they see the possibility of an embarrassing upturn in the unemployment rate and a decline in tax revenue that would add to the already swollen deficit.

Not all economists agree with Martin that a growth recession is a serious possibility (when have all economists agreed on anything?). Monetarists, for example, who blame the Fed's tight monetary policy from March to October 1984 for the current slowdown, predict some improvement in the economy later this year because the Fed has since eased up some.

Thus, Robert J. Genetski, senior vice president of Harris Bank of Chicago, says "interest rates have moved lower amid concerns over a weak economy. However, the economy is not weak. Rather, it is on the verge of a period of rapid growth . . . For the entire period since last October, the money supply is up 10 percent at an annual rate. During the first part of this period, interest rates dropped sharply. Then sensitive areas such as autos and housing rebounded. The final step in the sequence of events will be a faster increase in the sales pace throughout the entire economy."

No one can doubt that the Fed's policy swings have an effect on the economy. But perhaps a more important and basic factor in the slower growth of the economy since the middle of last year has been the negative impact of the overvalued dollar on American manufacturing industries.

In effect, since imports represented 14.5 percent of the value (in constant dollars) of all goods purchased in the United States in 1984 -- that's three times as big as the import share was 20 years ago -- a sizable amount of "gross national product" was transferred from this country to the nations where the goods were produced, along with the jobs connected with those goods.

This process is referred to as "leakage" by economist Rimmer de Vries of Morgan Guaranty Bank -- a leakage abroad of domestic demand through the trade deficit. For 1983 as a whole, 2 percentage points of the 8.7 percent rise in domestic demand leaked abroad.

"Leakage may now be worsening. Robust retail sales contrast with sagging industrial output and faltering overall employment gains . . . U.S. protectionism is stirred by the trade deficit. The sight of foreigners deriving handsome benefits from U.S. expansion is galling to domestic industries suffering competitive handicaps," says a Morgan analysis.

Genetski pooh-poohs the leakage theory, arguing that the money spent for imports "is available and will be used for the purchase of U.S. goods." But the Fed's Martin cites the decline in manufacturing production, and the loss of jobs, "some of which appears to be permanent." Commerce Department figures show that every manufacturing industry group except for autos and aircraft had lower profit margins in the second year of this recovery than in the prior expansion (beginning in 1975). Autos, of course, were aided by the "voluntary" quotas, and aircraft by the defense buildup.

Thus, it appears that the trade deficit, exploding in the past two to three years, finally has become the main roadblock to resumed growth of the American economy. So long as the dollar remains on a high perch -- and even the gloomy first-quarter statistics haven't caused a significant tumble -- American exporters are going to be at a competitive disadvantage.

If the huge American budget deficit remains untamed, the danger is that the government will find itself paralyzed: The Federal Reserve, fearing a new inflation, will be inhibited in its desire to help boost domestic activity by a substantial reduction in interest rates. And the White House hardly can resort to fiscal stimulants when it already has a budget close to $200 billion in the red.

This all points to the urgency for Congress to do something meaningful about the budget deficit, a hope that was piously endorsed by the Bonn summit. It's the one step which might encourage enough of a slide in the dollar to take the sting out of the trade deficit. But even that's unsure: The reason the dollar has stayed strong, despite the spate of weak economic reports, is that the United States still looks like a good place in which to invest, compared to Europe.