Out of this word

The greatest science fiction imagines universes wholly unlike anything we have ever seen before

Revenge is Sweet/Breed

"Like" is the most ubiquitous word of our time. And, in its comparative form, it is probably the most representative.

Teenagers use it to insert facial expressions into sentences, because words just fail: "So I'm like . . ." And it governs our critical response to almost everything we hear and see, allowing us to avoid giving basic factual descriptions. "Well," we say, when we're talking about a book or film, "it's a bit like X." And nowhere is "Well, it's a bit like X" more of a dominant response than in the field of science fiction. All SF, it seems, is now a bit "like" other SF.

A good example is Duncan Jones's recent film Moon, about a man living in total isolation on the lunar surface. Most reviews of it consisted almost entirely of either, "He's David Bowie's son, but let's not go on about that, but did you know he's David Bowie's son?" or, "Well, it's a bit like 2001: a Space Odyssey (1968)", or Solaris (1972), or The Man Who Fell to Earth (1976), or Silent Running (1972).

I think this is significant, not only because one of the greatest pleasures of any art form is that it can make us think, "I've never seen/heard anything like that before," but also because it is surely one of the particular duties of science fiction to show us things that are startlingly unlike those we already know.

In Postproduction, his influential book on contemporary visual artists, Nicolas Bourriaud argues that "since the early 1990s, an ever-increasing number of artworks have been created on the basis of pre-existing works; more and more artists interpret, reproduce, re-exhibit, or use works made by others or available cultural products . . . It is no longer a matter of elaborating a form on the basis of a raw material but working with objects that are already in circulation on the cultural market."

The raw material of science fiction is the imagined future. But certainly in the case of Moon there is often an acknowledgement that the future has already been pre-imagined. In other words, Moon accepts that, at particular points, most of its viewers will think, "Ah, now we're in Kubrick-future", or "Oh, heading into Tarkov­sky territory now". Where it hopes to tell its own story is in the transitions, overlaps and - more ambitiously - the gaps between these zones of familiarity. Which is not to say that 2001: a Space Odyssey arrived ex nihilo, merely that people leaving the cinema after its first run in 1968 were very likely saying: "I've never seen anything like that before." This isn't a possible reaction to Moon. Instead, the main argument of Postproduction fits Moon very well. It is a post-sampling film; it exists, in some way, as a remix of past futures.

At the other end of the spectrum, you have Philip K Dick. During his lifetime, he was just about as trashy a cultural producer as you could find. Not in his own head (and what a polydimensional location that was) - there, he was the most important artist alive. Yet even the title of a novel such as Our Friends From Frolix 8 precludes it from winning the Pulitzer. And there's a PhD to be written on how SF cover art in the 1960s and 1970s by itself caused the ghettoisation of some very considerable writers. (Compare Dick's first paperback editions to the numbingly sober cover for Doris Lessing's The Making of the Representative for Planet 8.)

However, a total turnaround has occurred in Dick's reputation, to the extent that he has been canonised by inclusion in the standard-worksy Library of America imprint, sitting alongside Abraham Lincoln and Harriet Beecher Stowe. But the best comparison would be with Edgar Allan Poe and H P Lovecraft, who have also made the weird journey from pulp to classic fiction - who have also been assimilated, in other words. I don't think this is necessarily a good thing. Vulgar they may have been, but at least the original covers of Dick's books were visually alive and engaged with their contents.

One of the defining characteristics of Dick's work is how embarrassing it is. Here is a writer who, in quest of his own imagined future, is prepared to be both grotesque and grotesquely wrong. Hunches that no one else would have entertained are routinely followed up; indeed, they are quite often Dick's starting point. They are also the elements that most often get cut when film-makers start adapting. Do Androids Dream of Electric Sheep? (1968) becomes Blade Runner (1982), and the robot sheep (quite an important factor in the novel) are nowhere to be seen.

One of the problems of the contemporary approach to the imagined future is that our visions are just too damn tasteful. There is now a well-established genre that you might call "classic SF", of which the latest Star Trek outing would be a good example. Here is a film about the future that relies entirely on familiarity - even down to the final, climactic confrontation with the ultimate SF baddie, vagina dentata. (See Independence Day, Aliens, Starship Troopers and so on.) Wouldn't want to disappoint the prepubescent boys, now, would we?

I've been discussing films because they undeniably dominate our visions of the future. When I began writing my own SF novel, Journey Into Space, I knew that however much effort I put into creating a believable interplanetary spacecraft, readers would, if I said it was dirty, imagine it as "a bit like the Nostromo" (Alien) and, if I said it was clean, as "a bit like Discovery One" (2001). My only solution was to leave the spacecraft, the UNSS Armenia, as indeterminate as possible - and to centre as much of the action as I could in the heads of the characters. Certainly I was hoping that readers, in the opening section, would think, "I've never read anything like this before."

J G Ballard's approach to science fiction still holds great potential: future technologies are all very well, but what about future psychologies? In his cyberpunk novels of the 1980s, William Gibson made great efforts to force hybridity on his characters. They are part-human, part-cyborg, part-net. Psychologically, however, they could all have stepped straight out of a John Ford western. The problem faced by SF writers is practical: create a hero who is believably post-human and most readers will lose all sympathy with him. But it is also formal: the novel exists to portray human lives and human struggles.

A few years ago, cinema reached a defining moment. It is now technologically possible to control every pixel on a vast screen, which means that it is possible (given sufficient resources) to create and project any arrangement of lines and colours that human beings are capable of perceiving. Just think of it - what power! However, all that this has served to do, so far, is demonstrate the limits of the contemporary imagination. We are furiously remaking classic SF, only bigger, louder, faster. It's all of it willingly "a bit like . . ." It's all of it post-production.

The greatness of science fiction rests in its unwillingness to settle for mere "like". As an example, I would cite Stanislaw Lem's novel Solaris, which succeeds in creating a truly alien alien.I don't believe that SF is, as some people say, always essentially about the present day. I began reading and writing SF and fantasy because I hated the present day, and wanted to get as far away from it as possible. While nowadays I'm a little more reconciled to life on earth, I still like my imaginary worlds to be unlike anything I've ever seen before.

Toby Litt's "Journey Into Space" is published by Penguin (£7.99)