Have you looked at the economic news lately and wondered who really did win World War II?

Somebody at NBC News evidently did, and came up with "If Japan Can . . . Why Can't We?" -- an "NBC White Paper" on Japan's burgeoning productivity and our lagging one -- to be aired tonight at 9:30 on Channel 4.

It is a thoughtful, often depressing and sometimes fascinating examination of what makes and maintains a work ethic, and why we may end up freezing to death in the dark but the Japanese won't.

It is also an interesting piece of television journalism, using interviews, factory shots, even personality profiles to punch home the bad news (if it is news) that bureaucracy, grasping management and grubbing unions are wreaking havoc with American productivity and that the Japanese, with what narrator Lloyd Dobyns calls their society-by-consensus (versus ours "by confrontation") have become the world's leading prototypes of efficiency and quality. Not only that, but their productivity is now third in the world, second only to the United States and the Soviet Union, and moving up.

For a devastated country which, in the 1950s was synonymous, as Dobyns notes, "with trash," Japan has come a long way: cares, small appliances, computers . . .

The runaway star of "If Japan Can . . . " is a 79-year-old statistical analyst for whom Japan has named its most prestigious industrial award for productivity. Never mind that he's an American, lives in Washington and works out of his home. W. Edwards Deming made Japan what it is today, and the Japanese are the first to admit it. According to NBC, a few American firms, principally Nashua, a copying company, are beginning to catch on that Japan made it by using American techniques devised by an American productivity expert.Somewhere, though, while Deming was exporting American know-how, the local version seemed to get lost. "Deming," says Nashua's president, "is the father of the third wave of the Industrial Revolution.

Deming, himself, is something less than optimistic, perhaps reflecting his lack of recognition at home.

"If Japan Can . . ." was written, directed and produced with the kind of imagination and instinct for what television can do that often brightened NBC's now-defunct "Weekend." It is not surprising to discover that it is the old "Weekend" team -- Dobyns, executive producer Reuven Frank and producer Clare Crawford-Mason who made it. It was directed and co-produced by Ray Lockhart.

Alas, in an element where ratings are the chief nutrient, it also contains the same seeds of destruction that felled "Weekend." After all, who wants to watch an hour and a half on productivity when all you really want is to find out who shot J.R.?

Just one more thing, for whatever it's worth: The video cassettes from which this program was previewed were made in Japan.