THE MYTHS imagined in different societies at different times may be very different in appearance, but the business of myth is always the same: to offer orientation and guidance in life, to give people clues as to what is worth doing and how to do it.

In the stories that we project into times yet to come and in the adventures we imagine humans having in other worlds, it is possible to discern the beliefs and conflicts of the present moment written large. If you want to know what is really going on in our minds and in our society, you could do worse than to look into the mythic mirror of science fiction.

Worlds (Viking, $12.95), a novel by the young Vietnam veteran Joe Haldeman, is an unblinking presentation of our present problems. Worlds is a work of extrapolation set 100 years in the future. The problems that we have now are the same problems that exist then, only worse. Pollution is barely kept at bay by electronic barriers. Violence is pervasive. The earth is on the edge of global catastrophe.

Around the earth there circle 41 orbiting colonies, high-technological refuges from the disaster of earth. The protagonist of Worlds is a spacer girl who descends from one of these worlds to study in New York City. Her experience of earth consists of assault, rape and senseless revolution. Her response to earth is a steady dose of tranquilizers, followed by escape back to her spacer world.

Worlds is orthodox science fiction carried out to its bitterest conclusion. Haldeman says that technological solutions to our technologically-generated problems can be no solution at all, but at best the promise of a way out for the privileged few. (And we can't even believe that. If techno-civilization is a blight that will destroy the earth, we must expect the blight to infect the spacer worlds and destroy them, too.)

King David's Spaceship (Simon and Schuster, $11.95) is another and more simple-minded work of technological orthodoxy by Jerry Pournelle, an unabashed technocrat half-a-generation older than Haldeman. Pournelle's book radiates confidence and good cheer. It even has a protagonist sure in his sense of purpose -- something lacked in all our other books.

Like the old-fashioned science fiction of 30 years ago, King David's Spaceship presents science as the answer to all questions. But Pournelle can make this case only be setting up a strange ad hoc situation where science is both the question and the answer, and all the crime, craziness and degeneration that obsess Haldeman are simply set aside.

In Pournelle's story, some hundreds of years after the fall of a human interstellar empire, a planet that has climbed back up to the technological level of 1870 is discovered by the Imperial Navy of a new Second Empire. If this lost planet can demonstrate its technological competence by proving that it has space travel, it can take its place in the empire. Otherwise, it will be freely exploited as a colony planet -- just like some technologically backward bit of Africa in 1870.

King David's Spaceship is concerned first with an expedition to a barbaric planet where the high science of the First Empire is still preserved as religious knowledge, and then with the construction and launching of a crude spaceship. This novel is a romp, a technological fairy tale, but it can't be taken seriously for a moment. Even to partake of its exuberance, you must close your eyes, promise not to think, and turn the clock back.

There is even less to be said for Project Pope (Del Rey, $10.95) by Clifford D. Simak. Simak has been writing science fiction since 1931 and it shows. All the familiar Simak materials are here: robots, aliens and telepathic explorers. But the handling is tired and routine.

Project Pope is an expression of scientific fundamentalism. A young doctor flees a feudal planet. He meets a female investigative reporter and together they travel to a planet where robots have founded a religion with a computer pope. But the characters lack both personal background and motivation, and the plot lacks tautness and direction. All that are left with, finally, is one more iteration of the gospel that rational science is the one road forward, in all cases to be preferred to fuzzy-minded religious faith. This may have been enough to say 50 years ago, but it doesn't begin to answer the questions that haunt Haldeman.

Terra SF (DAW, $2.25), a collection of current European science fiction edited by a Frenchman, Richard D. Nolane, and translated from eight different languages by Joe F. Randolph, reinforces this point. Quite aside from the frequent incomprehensibility of the translation, this is not a book to recommend to the casual reader. The Europeans were casualties of that ancient war between religion and science that Project Pope so dimly echoes. They ceased to believe in traditional religion, but never quite accepted the new religion of science. For them, science fiction has been a borrowed medium, a literary convenience and no more.

The common message of all the stories in Terra SF is hopelessness. Life is dreary and doomed, society is oppression and existence is a cheat, and there is no way out. The future and other space will be equally awful.

There is a better hope, however. Not all current American sf books are hung up in rote repetitions of scientific faith. There are novels that are tentatively attempting to alter our entire frame of reference in new directions. One of these is Junction (Dell, $2.50) by Jack Dann, a young writer of Haldeman's age.

Junction is a reality trip. It begins in a small American town existing on the brink of Hell -- an area of chaos and mutating forms. The scene shifts to a grotty near-future New York City, and then shifts again. Not much happens in the story and it is all vaguely told. Eventually, however, a transcendent intelligence explains that the universe is turning into a web of overlapping consciousness. Everyone is dreaming everyone else.

This offers a potential way out of our current dilemma. The problems that science can't cure might very well yield before a recognition of mutual interdependence. But Dan can't quite accept his own vision. His protagonist rejects reciprocal maintenance as demonic and flees into one dreamworld after another in search of a stable autonomous reality. But he never finds any.

The message of an even more provocative novel, Robert Anton Wilson's Masks of the Illuminati (Pocket Books, $2.95), is that we may not have any choice in the matter. Multiplex constantly-altering consciousness may be our future lot -- and the only thing to do is to learn to live with it.

On the eve of World War I a young Englishman is initiated into a mysterious secret society. Occult studies, dreams and visions, strange encounters and coincidences, and powerful sexual temptations combine to dislocate his sense of reality. At the point where Dann's character retreats, Wilson's protagonist is fortunate enough to stagger into a bar in Zurich, Switzerland, where he falls into company with James Joyce and Albert Einstein. These archetypal strange thinkers listen to his story and help him to make sense of his wierd experience.

The ultimate message of Masks of the Illuminati is the suggestion that the disorder and misery of the 20th century has been for a higher purpose -- the alchemical production of the new and more flexible-minded humanity. Dare we believe this? If our alternatives are rote scientism and total despair, then perhaps we had better give Wilson's novel our most serious attention.