There has been much discussion on the internet lately, as always, about what is fantasy, what is science fiction and what’s the difference between the two. Lots of intelligent people more eloquent then me have discussed the issue at length. But it seems to me that the division between the two genres is rather artificial and arbitrary.

A more interesting division can be drawn between what I would describe as rational speculative fiction and non-rational speculative fiction. Both fantasy and fiction, and all other forms of speculative fiction, can be divided into one or other of these categories.

Rational fiction is the type of fiction in which all that happens is explained in a rational manner, or in which it is implied that all that happens could be explained in a rational manner. Hard science fiction is an entirely rational genre, as is the ‘mundane’ SF movement. In both of these, all that is allowed must be explainable by either known science or extrapolated science.

Of course, it is not just hard/mundane science fiction that fits in the rational category. Space opera and social science fiction can equally well fit into the category. Peter Hamilton rarely explains all of the sfnal elements in his space operas, but without doubt it is implied in the stories that everything could be explained rationally. Likewise, Octavia Butler’s Parable... books are rational in that they extrapolate logically from Butler’s observations of society.

Rational fiction doesn’t just map onto science fiction, however. Much fantasy can be classified as being rational. David Eddings’ Belgariad series, despite the existence of ‘gods’ and magicians, explains magic in terms that of something very similar to Newton’s laws. David Gemmell’s Drenai series eventually explains its magic as originating from relics of a past civilisation. In Robert Holdstock’s Mythago Wood, the mythagos themselves are explained as being produced by energy from ancient trees interacting with human ancestral memories. The Harry Potter books, despite their extravagent magic, are rational. In all of these cases, and many more, it is implied that the magic that makes the book fantasy can be explained in rational, logical terms, even if those terms are not the same as the ones that our world operates by. Similarly, rational science fiction can happily accommodate the ideas of time travel and mental powers, because they fit within the rational structure of the story world.

Non-rational fiction on the other hand contains significant elements that cannot and are not explained in any rational manner. At the most extreme we have surreal fiction, where there is no cause-effect and no logic. Fairy tales and ghost stories, too, are more often than not non-rational.

Fantasy can often be non-rational. The dark tower in Stephen King’s Dark Tower series is a deeply non-rational element. The dual ending in Robert Holdstock’s Lavondyss cannot be explained in any rational manner, which places this sequel to Mythago Wood as non-rational. Hal Duncan’s Vellum, James Stoddard’s High House and Bradley Denton’s Lunatics are non-rational tales. At the more surreal end of the spectrum, Benjamin Rosenbaum’s Red Leather Tassels and The Ant King: A California Fairy Tale are non-rational. Theodora Goss’s Pip and the Fairies and much of Kelly Link’s work also fit in this category. There is always ambiguity in these stories, and the writer carefully avoids giving explanations for their key speculative elements.

Finding non-rational science fiction is a tougher proposition. Science fiction has fallen very much under the spell of scientific method, and thus it is overwhelmingly rational. To find non-rational fiction one usually either has to move outside genre science fiction, where the science is less important than the way the future can be used to comment on society (see, for instance, Margaret Atwood’s science fiction novels), or back in time to the pulps (although much pulp science fiction is simply fantasy in a then-necessary disguise). One might argue that Iain M. Banks’s Excession is a non-rational science fiction book, and Justina Robson’s Living Next Door to the God of Love edges on the non-rational simply because the science underpinning it is so vastly alien. But to attempt to write non-rational science fiction in genre, one must be brave. Neal Asher’s short story Mason’s Rats, a non-rational science fiction piece, was roundly attacked in a Tangent Online editorial for its non-rationality, even though that was what gave it its strength.

Non-rational fiction requires there to be something that cannot be explained. It thus has much in common with religion. At the heart of it is a mystery, the unknowable. Like a miracle, the non-rational is the intrusion of something that can’t be explained into a rational world.

Many stories, of course, have both rational and non-rational elements. Only in purely surreal stories will you find no rational elements. Only in the hardest science fiction or fantasy will you find nothing non-rational. I would define a story as non-rational where there is a significant element that is non-rational. George Lucas’s original Star Wars trilogy is a non-rational story, due to the non-rational nature of ‘the force’. In the prequels, however, he introduces the notion of ‘mitoclorians’ and makes the story a rational one (incidentally ruining it in the process), in that the non-rational element has now been made rational.

As writers we are often encouraged to explain everything we write. We are told that even magic must be constrained by a logical system. But this is a necessary condition only of rational fiction, not non-rational fiction. The types of fiction are fundamentally opposite, while the distinction between science fiction and fantasy is artificial. The explain ‘rule’ that applies to rational fiction is the death of non-rational.

As a writer I find that my short fiction falls almost entirely in the non-rational category while my novels are generally rational. Looking for examples of non-rational fiction for this entry, I find it far easier to find examples of short non-rational fiction than non-rational fiction at novel length. I think this is because, as readers, we generally want to make sense of the universe as it exists in story. We like mystery, but there is a limit to how much mystery a reader brought up in the rational, logical mindset of the modern west is able to accept. And for a writer in this tradition, brought up on a diet of rational speculative fiction, sustaining a non-rational story convincingly for a long period is difficult. Thus the non-rational in a novel is often subsumed by the greater rational element.

Finally, I want to draw a distinction between non-rational and irrational. I see the non-rational as being a very deliberate, very controlled intervention of that which can’t be explained. The irrational, on the other hand, I see as being the accidental insertion of something unexplained, coming about by the incompetence of the author.