AMERICANS WHO PLAN their careers, home buying, and otherwise structure their lives on the assumption that America has entered the "post-industrial era" better take another hard look at what is happening.

This is supposed to be the "electronic age," in which more and more Americans will work at home, using their TV screens as their desk tops. Information served up electronically, not muscle power, is to be the key factor. Heavy-duty industries are to fade into the background, as farming did when America first industrialized. Computers, labs, and professional work are to dominate the post-industrial age.

Well, don't rush to trade in that lunch box for a briefcase or a portable computer terminal. A not-so funny thing happened on the way to the post-industrial society. Under-development set in, as did OPEC, and Soviet troops took yet one more country. Decades of over-consumption and under-investment allowed the basics of the American economy to deteriorate. It now requires a decade of "re-industrialization," that subject of much recent debate. It refers to the need to shore up the foundations of a modern well-functioning economy: the transportation systems, power sources, communications, and human resources. So must we replace all those machines and factory buildings which are worn out.

While it is true that some of the jobs such catching-up generates are in the computer-rich, highly skilled sector -- say, developing the design of new steel mills -- a good part of the work entailed is the all too familiar, blue-collar heavy-duty labor of casting steel, transporting beams, pouring asphalt.

God, no, say the post-industrial gurus; that is not where our "comparative advantage" lies. We are in growing competition with the Third World, writes corporate sage Peter Drucker. They have large numbers of unskilled young workers, willing to work at low wages. Let them make steel. We ought to concentrate on the high-technology things which we are best at.

But this raises several difficult questions. If America is to become a kind of Switzerland, which imports most basic goods but makes only the post-industrial equivalent of watches, what if one day the exporters of steel or merchant ships pull a 1973-like blockade on us? Does consideration of national security alone not dictate that at least some of these basic goods will be produced at home, the way Britain, cursed with poor farming weather, decided that it needed to maintain at least some farming on its island?

Moreover, if the Third World is better (or at least less expensive) at blue-collar work than contemporary America, and Japan and West Germany beat us at the high-technology game (say, as they did with fuel-efficient autos and TV sets), what will we do? Build America's economic future around making apple pies, Cokes and whatever other "comparative advantage" remains? Also, it is important not to forget that the United States has its own millions of less well prepared persons, augmented by a massive inflow of immigrants, especially from Mexico. If we allow their blue-collar jobs to be exported (as we did in textiles), what will they do in the post-industrial age? Consideration of national security and sensitivity to the less privileged, to say nothing of fear of more Miamis and Watts, all suggest that a rush into the post-industrial age is not the road to the promised land.

Sheer economic considerations also require a large measure of return to basics. The ultimate significance of OPEC is that cheap energy has vanished, and -- you've heard it a thousand times, but it is still true -- America's economic future requires finding substitutes for oil. Whatever one feels about solar or nuclear's energy, in practice the U.S. energy future for the next decade at least says: dig more coal.

What that requires is 200,000 more coal miners by 1985, more blue-collar workers to build more boxcars to carry the stuff, and more grunts to redevelop railroad beds to transport it. Those who seek America's frontier ought to recognize that it is here where much of the "new action" lies. It will also require large amounts of money. One major synthetic fuel plant, using 30,000 tons of coal a day to produce oil, would cost $1.5 billion to $2 billion. Converting the utility oil burners to coal users will cost more than $10 billion.

What does all this mean for people's careers, homes and futures? Post-industrial careers will not be as inviting as expected. Research and development has been leveling off in the last decade, in effect falling as percentage of GNP from 3 percent in 1974 to 2.3 percent in 1979. This does not bode well for those preparing for high-technology professional jobs, although admittedly there will be some need for more computer people.

Education faces a surplus of teachers and faculty as there are fewer kids in aging America. While many a college graduate will be looking for a job, there will be good money in blue-collar jobs pay better than white-collar ones. Especially lucrative is blue-collar work related to energy. For instance, fully experienced coal miners even today can make $10.60 an hour, and they are not untypical of the industry. Or take the Alaskan oil pipeline: a heavy truck operator earned between $16-17 an hour; and a line driver, who carried freight from Fairbanks to Prudhoe Bay, earned approximately $13.50 an hour. And at the height of pipeline construction, in 1976, many workers had 50-60-hour work weeks, getting time and a half pay of these wages. And it is hard to foresee that coal miners' income and other terms of employment will not continue to improve, if many more will have to be attracted into this tough business. While some of the kids who told their parents they would rather go and work with their hands than go to college may have been just "going through a stage," others -- especially those less talented academically -- are just a bit ahead of the times, well suited for the coming era which will see that post-industrialism is all too slow in coming. Mothers who once bragged about "My son, the doctor" will soon have to learn to one-up their mah-jongg partners with payroll news about "My son, the coal miner."

Another closely related development is the rise in cost of higher education. It will be worth less in the '80s if my re-industrialization forecast is born out, and it already costs much more each year to acquire. Quite properly, more and more young persons and parents aks: Is it worth it? q

Another vastly underreported, relevant development is the huge increase in two-year junior and community colleges. The media tend to focus on the musings at Harvard, Yale and Dartmouth. But the higher education action is in the stupendous growth of hundreds of college which provide little liberal arts and lots of occupational training.

In the recent past vocational education was seen largely as a stepchild of general education. However, when America was first industrialized, acculturating farm kids and immigrants for work in factories was a major goal of education. This pivotal role may now be reinstated.

In the past three decades, college education in America was more than a way to make a career it was the avenue for class mobility. To gain a college degree was the ticket out of working class and lower middle class into the upper middle class. It connoted leaving behind overalls and box lunches, and donning suits and briefcases and all the other status symbols of success from drinking wine instead of beer to speaking a "higher" brand of English. What does the need to re-industrialize imply for class mobility? Mainly, I suspect, that money will again play a more important role, next to college education. There were always many Americans who made it "the other way." In previous generations, they did it by cornering the grain market, or gaining control of oil refineries; more recently the technique has been to win franchises to cable TV or to excel in the wholesaling of marijuana. But these Americans were often made to feel uncouth. In the next decade, as more and more English Lit types will drive cabs, and more and more coal operators and solar heater dealers laugh their way to the bank, status symbols may again tilt a bit toward the flashy -- or basic (open collar) -- and away from the pin-striped three-piece suit. Members of the upper middle class with a college education will be proportionally fewer; more often -- as before World War II -- will there be displayers of new wealth.

But what about the standard of living for most Americans? Will not the large investments in energy development, railroads, and all else that goes into re-industrialization slow the growth of the production of consumer goods and services? Almost certainly it will continue to do so; already real growth in the standard of living has significantly slowed down. For the '80s, if the U.S.A. is to shore up its productive capacity, adjust its energy base and build up its defenses, relatively little will be left for a higher standard of living. Our main solace might be that if all goes well," the economic/industrial machine, which provided for the good life, will hum again, in full swing, by 1990.