This is something that is both very easy sounding and extremely difficult. It is especially difficult in the realm of fantasy and science fiction, as well as other genre writing like horror or supernatural works. People read fiction to be transported to another place, to give them some experience that they would not otherwise have. The reader of a work of fiction must always and automatically “suspend disbelief” whenever reading: he must put away what he knows to be “true” in order to immerse himself in the “reality” of the story. This is why details can sink or save a book: too many things that don’t ring true, and the reader’s ability to suspend disbelief is undermined. The reader stops being an active participant in the book’s adventures, and turns instead into a critic, a scientist, an observer looking for what is wrong rather than enjoying what may be right.
And the idea of “suspension of disbelief” is nowhere more crucial than when writing fantasy, science fiction, or genre works. In addition to the first layer of suspension (the fact that the reader is not really participating in the fictional adventures of the book’s protagonists and antagonists), there is another layer of disbelief that must be dealt with: the question of magic. Of alien technologies. Of ghosts and specters. These “make believe” aspects of genre writing present a special problem, as they inherently inhibit the reader’s ability to put aside the “real” in favor of the “read.”
The best way to deal with this problem is a facet of the critical characteristic of clarity. The best genre work always takes place in fully realized “worlds” with clear, easily-understood (or at least fairly easily-understood) “rules.” The presence of such rules can mean a fantasy windfall. Their absence can mean disaster.
One example of this is the blockbuster hit The Sixth Sense, one of the top-grossing suspense/supernatural thriller movies of all time. The rules are set up very early on in the movie: the movie’s young protagonist can see ghosts. The ghosts do not know they are dead. He can help them “move on” by finding out what unfinished business it is that they are remaining to deal with. These simple rules set the scene for both an engaging ghost story and one of the greatest surprise endings in modern cinematic history. And the surprise is complete and utterly earned because it follows the rules.
Another example of literary rule-making is in The Lord of the Rings saga. There, Tolkien draws upon a much wider palette in order to paint an epic portrait of an entire world at war. Unlike The Sixth Sense, which is an intimate, almost claustrophobic movie, The Lord of the Rings follows dozens of characters throughout the various landscapes of Middle Earth. The magic use is prolific and varied. But still, there are rules, and they are scrupulously adhered to. Elves have a natural inclination toward and protective sense over all things of nature. Dwarves prefer to be underground. Gandalf the Gray is quite a different person than Gandalf the White. Each has set characteristics, set attributes, and these are as unchanging as the DNA of any real human being.
A final example (if I may) can be found in my own work. One of my books is called Billy: Messenger of Powers. It’s a young adult fantasy about a boy who finds himself embroiled in a magical war between two groups: the Dawnwalkers, who want to protect and serve humanity; and the Darksiders, whose goal is nothing less than world domination. As with The Sixth Sense and The Lord of the Rings, clarity is key. Billy (the hero) is drawn into a world of magic and wonder. But the wizards and witches he meets can’t just run around “doing spells” willy-nilly: there are rules, and those rules must be laid out with enough clarity that the reader not only understands the world of the story, but believes in it.
Simply put, clarity is key in all fiction, but critical in sci-fi, fantasy, and other genre work. A muddled magic system, an alien technology that is capable of some things one moment then incapable the next, these can be the genesis of confusion in the reader… and signal the death knell for an otherwise viable series.