One of the more interesting thing about blogging Masello's rules is finding out just how completely Masello can encapsulate his advice in one phrase. His thirteenth rule, "Play God," is actually backed by a short essay that gives some very good, more specific advice.
The idea that writers play God is not a new one, of course. As Masello points out, when you face a blank sheet of paper you essentially have the chance to create a world of your own. Anything can happen in that world, and it's up to you to decide what.
However, he goes further and points out that just because anything can happen doesn't mean it should. If you create a world, you need to create rules for your world, and you need to play fair with your reader. Your world must be both credible and consistent.
This is a common piece of advice given about writing science fiction and fantasy, and it's a piece of advice I agree with wholeheartedly. The best fantasy stories are the ones in which the writer has really gone to town, and created consistent rules for the magic and ecology of the world. The best science fiction also incorporates a consistent view of the world, with no surprises that haven't been planned for beforehand. What's the point of following the desperate plight of a band of heroes, only to discover at the end the writer gives them a magical weapon or a piece of advanced technology that solves the problem for them in a jiff?
Even a surreal landscape needs to have some sort of logic behind it. If there is no pattern, readers will look for one anyway, and will feel cheated if the writer just shrugs off their concerns.
(Digression: Nomi and I are fans of the TV show Lost, and like everyone else I'm enjoying the puzzle of trying to figure out what's really going on. My own theory is that the only logical explanation for all the events that have taken place on the island and in the past is that it's all some sort of alien experiment. And, as Nomi says, when your logical explanation is that it's aliens, you know that the world is a weird one.)
Masello comes to this rule honestly, by the way; he's written horror novels and TV episodes for shows such as "Charmed," in which there are rules of magic, but consistent ones. (Or at least, there's an attempt to be consistent.)
Finally, I'd say that half the fun of writing is creating the rules by which your world will run. If you don't enjoy doing that, why create new worlds in the first place?