Marvin Cetron has the numbers in his head. In 1980, he says, 45 percent of American women held paying jobs. By 1990 it will be 65 percent; by 2000, 75 percent. Over the same period, the workweek will drop from 39 hours (1980) to 32 hours (1990) and finally to 20 hours (2000).
Result: ''The family still puts in 40 hours, but it's husband and wife,'' he says. ''That means more leisure time, more recreation,'' he explains, ''if we learn how to relax and enjoy ourselves.''
A relaxed Dr. Cetron was obviously enjoying himself the other day as he talked about the firm he heads (Forecasting International, in Arlington, Va.) and the feedback from his year-old book (''Encounters With the Future: A Forecast of Life Into the 21st Century'').
A voluble former engineer with a reputation for shooting from the hip, he is one of an increasing number of professionals whose business it is to comment on the future.
Some, like John Naisbitt (whose best-selling book, ''Megatrends,'' also appeared last year), analyze the content of press reports. Others, like those at Chase Econometrics, depend heavily on economic indicators.
Some fire warnings, like the Club of Rome's 1972 report, ''The Limits of Growth.'' Others mingle awe and concern (like Alvin Toffler in ''Future Shock'') or speak of a coming visionary age (like the late Buckminster Fuller).
Some, calling themselves ''forecasters'' instead of ''futurists,'' try (as Dr. Cetron says he does) to ''quantify subjective judgments on the quality of life.'' Others, noting the popularity of jokes about economists and finding past projections inaccurate, turn to what John Elkins, vice-president of the Denver-based Naisbitt Group, calls ''the soft and fuzzy futurists.''
Diverse though they are, these for-profit prophets make one thing perfectly clear: that the public's desire to know the future is itself one of the megatrends of our age.
Why all this interest in the future? ''Because they're getting scared,'' says Dr. Cetron. Although he places less emphasis on the fear of nuclear disaster than do some of his colleagues, he explains that he published his book to help the individual ''reduce his uncertainty and his anxiety.'' Using computer analyses of hundreds of statistical indicators, trends, and ''major events'' in the news, he describes a future full of robots, empty of cash and checks (because replaced by electronic transfer of funds), and with ''the Japanese economic miracle'' giving way to the emergence of resource-rich Australia and Canada.
Several things worry him deeply: the weakening of the United States educational systems, the worldwide lack of potable water, and the breakdown of ''our basic building block in this country,'' the family. But while trying to remain neutral, he finds he's full of hope. ''I'm a realist,'' he says, ''and as a realist, I become very optimistic. I think there are marvelous things going on.''
On one thing the futurists and forecasters seem to agree: the heady pace of change. ''The traditional pattern has broken down,'' says Dr. Selwyn Enzer of the Center for Futures Research at the University of Southern California, ''and everybody has been looking for the new formula.''
Mr. Elkins agrees. ''We're going through some changes (in society) that we have difficulty explaining,'' he says. Unlike the changes of the 1950s and '60s , he adds, we're now ''changing the very rules of society'' - with profound effects on the institutions of family, church, health care, education, government, business, and nearly everything else. Not surprisingly, people want to know where the changes will take them. ''Our clients are more and more fascinated by the future,'' he says.
This desire for a knowledge of the future is, of course, not new. Some, like biblical figures, have sought it in prayer. Others, like Macbeth, have sought it in the mutterings of supernatural figures. These days, many plant their faith on technology - and look to a futurology made respectable by couching itself in numbers and running itself through computers.
Is this focus on the future healthy? In one sense, yes. If fear, as Franklin Roosevelt said, is the only thing to fear, then whatever gives us courage (either by warning of specific dangers or by alleviating unfounded anxieties) is a benefit.
But in another sense, maybe it's not so healthy. Sometimes our fascination with the future is at the expense of the present. Sometimes, fixed on what's ahead, we forget to cherish what's right here already - our children, for example, or the friendship of a neighbor, or even sunlight in trees.
For there is some truth in what our philosophers tell us: that the future is no more than an idea existing in the ''now,'' and that the present is reliable in ways that the future is not. If we're not careful, we could find that a study of that illusive idea of the future absorbs all our time - all our newfound leisure time.
That's not exactly what Marvin Cetron meant by encouraging us to ''learn how to relax and enjoy ourselves.''