It's been a weird few months. Ever since Black Monday -- Oct. 19, when the stock market lost a fifth of its value -- we've had two economies. One is the economy of the commentators and of the stock, bond and foreign exchange markets. Listen to them, and you hear the rumble of a great crisis. There's much turmoil and foreboding. The other economy consists of real people and businesses. It's boring and remarkably prosperous.

You're not crazy or misinformed if you feel confused. The stark contrast between the two economies suggests that today's economic "crisis" is something of a phony. The phrase recalls "the phony war" of late 1939 and early 1940. In September 1939, Germany attacked and quickly conquered Poland. England and France, acting under treaty obligations to Poland, declared war on Germany. But for months, there was almost no fighting. Everyone was agitated, but little happened.

There's a similar air of unreality to today's economic crisis. Just last week, for example, the Commerce Department announced that the U.S. trade deficit was $17.6 billion in October -- a figure far higher than expected. Predictably, the commentators and markets were noisy and anxious. Stocks and the dollar "plunged," said The Wall Street Journal. Interest rates "surged."

"Traders are confused and {investment} portfolio managers are spinning," one broker told the Journal melodramatically. In Zurich, an international trader said: "The mood was ... black." So the stock market "plunged" -- but only for a day. It bounced back in the next two trading sessions.

Switch now to the economy of real people and businesses. It displays little of this frantic behavior. Nothing since Black Monday indicates that this economy has been significantly affected by the market crash. Of course, there are some minor aftershocks. BMW sales are off; some investors don't feel so rich anymore. Surveys of consumer confidence show slight declines. But overall retail sales are still rising, and businesses apparently haven't sharply cut investment plans.

Businesses are most influenced by recent experience, and for many companies 1987 was a very good year. Consider the lumber industry. In the 1981-82 recession, it suffered. Many mills were shut. But in 1987, domestic demand for lumber hit a record, as it had in the previous three years. Although new housing starts were below the 1970s' peaks, the drop was offset by slightly bigger homes and a remodeling boom -- outdoor decks, family rooms and new kitchens. Since 1983, repair and remodeling spending has risen about 85 percent to more than $90 billion.

The story isn't exceptional. Plastics go into everything from garbage bags to toys, to construction pipes to soda bottles. In 1987, plastic production jumped 8.5 percent; that was nearly double the prediction at the start of the year. Exports have increased an estimated 19 percent. Sales of electronic semiconductors (the tiny "chips" and related components that go into computers and electronics products) rose 20 percent in 1987.

Nor is the gap between economic rhetoric and reality confined to the United States. In Europe and Japan, there's loud worrying that exchange rate changes will depress their exports. (The dollar's fall makes U.S. exports more competitive, while the rise of other countries' currencies hurts their exports.) Especially in Europe, some statistics paint a dreary picture. Since 1983, Europe's unemployment rate has exceeded 10 percent. In 1987, West Germany's economy is expected to grow a meager 1.5 percent.

Sounds grim. What Europe is actually experiencing, though, is a plodding prosperity. The unemployed receive generous benefits, and everyone else is reasonably content. As for West Germany, its economy "isn't in bad shape," says economist Norbert Walter of Deutsche Bank. Exports have held up better than was expected. Unemployment has risen only slightly, and consumer spending is strong. In Japan, the economy is more robust. Expanding domestic spending has offset weakening exports.

Which picture do you believe: the alarms of catastrophe or the bland reassurances? Perhaps both.

The old cliche applies: If you're not confused, you don't understand the situation. What the turbulence of the financial markets -- the stock, bond and foreign exchange markets -- signifies is that people no longer know what to expect. These markets reflect daily guesses about the future. Looking to the future, investors aren't predicting disaster. But increasingly, they can't see clear solutions to some of today's problems. Ignorance breeds fear, and fear breeds erratic markets.

No one thinks that today's huge trade imbalances -- the large U.S. deficit and big surpluses in Japan, West Germany and other countries -- can last. Neither does anyone know whether the world's major governments can or will take action to reduce these imbalances. No one knows whether the world is slipping into recession, whether inflation might revive in the United States or whether everyone will continue "muddling through." Perceptions change from day to day. Markets fluctuate. Large sums are won or lost. Naturally, investors become melodramatic. Their rhetoric is exaggerated, their instant analyses often wrong.

Despite its decline, the stock market is still roughly where it was a year ago, and that's about twice its 1982 level. But the acute anxiety of the financial markets and the apparent tranquility of the productive economy are a disorienting mixture. Indeed, the calm of the one amplifies the nervousness of the other. Governments act only if there's a crisis, investors and analysts say. They don't want a crisis and yet, in its absence, they worry that governments won't act forcefully enough. Then matters will get worse.

The stock market crash was so spectacular that we strain to find its meaning. We can't abide the thought that it was simply a random event without momentous significance. The trouble is that we barely know what caused the crash -- the details are only now being pieced together -- let alone what it means. Maybe today's crisis is phony. But there's an unsettling reminder from the phony war of a half century ago: In the end, it became very real.