Maybe President Reagan was counting on simple courtesy. After all, if he had invited Julia Child to dinner, he wouldn't expect her to pronounce Mrs. Reagan's souffl,e a fallen, sodden mess, no matter how obvious it was that something dreadful had happened to it.

Or maybe the president, who is given to an occasional lapse, thought he had invited George Gilder, the supply-siders' favorite pop economist.

Well, it wasn't Gilder. It was George Stigler, recent winner of the Nobel Prize in Economics. And no matter how Child might have handled the analogous situation, Stigler pronounced the president's economic souffl,e a fallen, sodden mess. Reaganomics, he told startled reporters, has the country "bumping along" in the throes of "a depression" as serious as the Great Depression of the 1930s.

A depression? Not even liberal editorial writers have called the present mess by any name worse than "deep recession." Had the Nobel laureate misspoken himself?

"Well, I think that's linguistics," he said, noting that, at age 71, he's old enough to recognize a depression when he sees one. But acknowledging that uttering the actual word may be taboo "within the city limits of Washington, D.C.," he told the White House press corps that he was perfectly willing to "change words."

It was a moment of excruciating embarrassment for the White House aides who accompanied Stigler, widely known as a free-market economist and advocate of government deregulation. And it got worse.

With no more sign of hostility than he might have displayed before students in one of his economics classes at the University of Chicago, he gently debunked supply-side theory as "a gimmick, or, if you wish, a slogan that we used to package certain ideas," rather than "an orthodox economic category."

In the same smilingly professorial manner, he offered that, if he were judging the president on writing an economics textbook, "He'd not get an A. Maybe an incomplete. I want to see what happens in the next two years."

The Stigler remarks would have been dismaying enough to the administration if he were just another economics professor. But since he was a Nobel laureate and invited guest at the White House mere days before an election widely viewed as a referendum on Reaganomics, they were little short of devastating. What made it all the more shocking is the fact that the interview came just moments after Stigler left a private discussion with the president, who clearly had expected Stigler to boost the administration's economic program.

Yet Stigler said nothing that millions of Americans didn't know on their own. Indeed, if most of us didn't believe that the economy was in desperate straits, the Stigler remarks wouldn't have mattered that much. The shock was that it was a distinguished royal guest, not a child along the parade route, who observed that the emperor was buck naked.

And he wouldn't quit. Even while red-faced White House aides were hustling him out of range of reporters -- the staffer's equivalent of Reagan's "Shut up!"--he chattered on about "striking similarities" with the Great Depression, "low levels of private investment in basic manufacturing" and other awkward economic realities.

Still grinning broadly, this Stigler for honesty told reporters how much he enjoyed Washington. "Oh, I love it," he beamed. "I come here once every three years."

Which, no doubt, is often enough for his most recent host.