I RECENTLY SPENT three weeks talking to Japanese roboticists: key people like Ichiro Kato at Waseda University and Shigeo Hirose of Tokyo Institute of Technology. It was easy to get them to talk about what robots will be doing in the next few years. Hirose sees hundreds of applications for his "snake" robots, including the use of a miniaturized version to slither quietly through human intestines, checking for problems. Kato sees larger robots -- building houses, working as loggers, cooks, delivery people -- replacing automobiles as Japan's major export product within 30 years.

It was much harder to get them to speculate on the consequences of all this. That's not our field, they said in effect. If you want to talk about consequences, go find a social scientist.

American roboticists, though slightly more willing to let their minds rove, tend to take the same line. Consequences are not their business.

So far, most social scientists don't suppose it's theirs, either. Last year, a couple of researchers named Charles Hollon and George Rogol did a search, and found exactly three "empirically based investigations on the non-technical effects of robotization." The study they then began makes four. Even those are pretty minor stuff. One, for example, is exclusively concerned with how business and labor leaders perceive the short-term effects robots will have on employment and on morale.

Joseph Deken's Silico Sapiens is thus a very timely book. Deken has a very lively mind indeed. He also has a well-informed one; he's Program Director for Information Science and Technology at the National Science Foundation.

The "Silico Sapiens" of his title refers, of course, to robots. Mankind is homo sapiens, the intelligent hominid. Robots are in the (very rapid) process of becoming intelligent machines. With their fast silicon brains and tireless bodies, they will be capable of round-the-clock work, creative thought, independent action, eventual reproduction. They are the second sapient species to evolve on this planet. How will that affect us earlier arrivals?

As you might guess, Deken thinks the results will be mixed. In the first half of the book, he tends to stress the gains, of which there will be many. First he describes (in a quite engaging narrative) the life of an active American family 15 or 20 years from now. Tom and Janet Master and their three children routinely employ dozens of robots, none of them human in form. They have a robot refrigerator which automatically takes inventory, wraps leftovers, suggests menus. They have robot servants of every kind, with a central computer to oversee this mechanical staff. They have robot simulators which can give any member of the family the close illusion of a trip to Moscow or Paris. Even robot tennis rackets, which double as coaches. In short, they have machine versions of all the privileges once reserved for the rich.

But that's only the beginning of the good news. Robots will also have freed our species from every kind of boring and dangerous work. Having a potentially infinite number of sense organs, as opposed to our meager five, they will be giving us a vastly richer picture of the universe and all its contents. Invited into our bodies, they will give hearing to the deaf, legs to the lame. Indeed, they've already begun to in 1986.

THERE'S ALSO A darker side. As Deken points out, robots will make ideal assassins and terrorists, since at least initially they will value their lives even less than the most committed PLO member. "Perhaps computer chips in their raw form will eventually be as controlled as nitroglycerin or plutonium is today," he says.

In their young strength, they may also tend to make us of the older race feel inadequate. "The robots will be immortal, and far better at doing many tasks than the species that built them." Will it still be fun to cook when your robot oven can always make a better quiche than you can?

Furthermore, as robots develop a degree of autonomy, they will inevitably develop some values that diverge from ours. This makes Deken nervous. It is not for nothing that he gave the human family in the book the last name of Master. Robots "are our tools and creations," he says, "to be kept in place as a subservient species by whatever methods we find necessary." Strong words, if not actually tyrannical. It is a measure of how fast technology is moving that even 10 years ago they would have been imaginable only in the context of some lurid science fiction story.

Deken doesn't cover every consequence. He is notably silent about what ordinary people (the Master family are near genius) are going to do with all their freedom, once robots take over the jobs, the housework, the tennis-coaching. But he has still written by far the best book I have yet seen on the future of robots -- and easily the most readable, too.