Because many political and business leaders say it is so, and renowned academics provide a theoretical base for so believing, a sense of industrial decline pervades American thinking.

If, by chance, it is forgotten, reports on the trade deficit, budget deficits, weak savings, low growth in gross national product and apparent weakness in exports restore it to the public consciousness.It is imbedded now, part of the national psyche, and reflected in a morbid sense of inevitable decline comparable to what overtook economic empires in the past. It contrasts sharply with the old self view of America as No. 1.

And it might not be justified.

Professor Richard McKenzie of Clemson University believes there is evidence in the past few years to question whether the thesis is America's fate and, instead, to wonder if it might be a fiction of well-intended but incomplete research.

Among his reasons for so believing is that much of the scholarly research that led to such assumptions were based on data for the 1960s and 1970s and that when such data are updated to the mid-1980s another story emerges.

After updating, says McKenzie, the data "no longer confirm (at least, with the same force ) popular and scholarly visions of relative decline." In short, many things have changed in the 1980s.

For example, McKenzie says U.S. gross national product in relation to GNP for the rest of the world did indeed decline from 43 percent in 1960 to 33 percent in 1975. But it has stabilized since then.

A similar pattern shows up in comparisons of American GNP with the GNPs of major developed countries, he says.

In proposing that many fellow academics have made incorrect assumptions, McKenzie is challenging some of the brightest academic writers of popular economic tomes, including Harvard professors Robert Reich and Paul Kennedy.

Kennedy, a Harvard historian who remains on some best-seller lists with "The Rise and Fall of the Great Powers," says the United States must learn how to manage its affairs so that erosion takes place slowly and smoothly.

In short, an assumption is made that the country is caught in the jaws of an unrelenting historical force and that if it cannot escape it can at least try to slow the inevitable and try to make the descent tolerable.

As an example of his thinking, McKenzie challenges the popular argument that the mounting international trade deficit is prima facie evidence of lost competitiveness, lost drive and a declining standing in the world economy.

In a paper published by Washington University's Center for the Study of American Business, he states that one reason for the big trade deficit is faster U.S. economic growth compared to many other nations.

"With more rapid growth, producers need more resources, many of which must be drawn from abroad in the form of imports," he states. "In turn, fewer domestic resources are available for the production of goods for export."

The decline in real U.S. exports in the 1980s, therefore, probably reflects a significant rise in domestic consumption, McKenzie says.

Again, while pessimists complain that the country is being sold to foreign interests, McKenzie compares the situation to the huge foreign investment in U.S. railroads in the 1880s, which was the foundation of the American empire.

He contends that the correct way to view such foreign investments is the same way we view exports of goods and services: They are "products" produced by the economy that are attractive to foreigners.

While recognizing that scholarly research has gone into many of the gloom and doom theses and that America does have serious economic problems, McKenzie suggests that some extrapolations may be premature and perhaps misdirected.