As an author, you have the god-like ability to create entire worlds made entirely from your imagination. If you want a world filled with talking trees, that’s great. A planet inhabited only by blue giraffes? Knock yourself out. There truly is no limit…however, there are limitations.

One of the most important of these is Internal Logic. Your readers will follow you anywhere (assuming they like your particular genre). If you lead them into your world of blue giraffes, they will happily reside there as long as you’ve set up your rules, the internal logic of your world, and follow them.

Let me give an example of a breach of internal logic: years ago I read a novel written by an acquaintance, set in our own world, with normal human characters who interacted as normal human characters do. All was well until somewhere in the middle of the book when he wrote about a couple having an argument in the living room of their New York City apartment, whereupon the husband “threw his wife’s straw hat into the aquarium, where it was immediately eaten by the piranha.”

Now. Anyone with even minimal knowledge of piranha habits knows they are meat eaters. They may eat some vegetable matter too. They are also about four to six inches in length. Does anyone truly believe a piranha will eat an entire straw hat? If you do, do you honestly believe our talented piranha could truly eat it immediately?

I read this novel at least twenty years ago and that piranha/straw hat detail is the only thing I remember about it. The author put it in, hoping for an easy laugh, but what he did instead was pull down the entire edifice of the world he had otherwise so carefully constructed.

(I’ve seen the same thing happen with actors, by the way. In an effort to get a laugh, they will put in a “bit”, an action, or expression that suddenly exposes the audience to the actor him or herself and tears them out of the “world” of the play. It doesn’t work. It is the piranha eating the straw hat.

I was inspired to write this post after seeing the film Alien: Covenant. The director Ridley Scott set up a world of high tech, aliens, and space pioneers…and then proceeded to allow his highly-trained spaceship crew to engage in one bone-headed, irresponsible action after another. The computer warns the crew not to go within eighty kilometers of an electrical storm or they will damage or destroy the ship.  Silly computer, thinking she was talking to calm, thoughtful, rational adults.  But no.  Instead, the acting Captain insists on taking it forty kilometers away. And okay, maybe he’s a nitwit.  Let’s give him that.  But with almost no trouble at all, he gets his second in command to agree to override the safety systems.  This truly was the Ship of Fools.

You go to an unknown planet with no idea at all of the life forms that may live there? Have you set up any quarantine systems? You have not. You let your stupid crew bring anything they want on board…which I didn’t mind so much as a quarter of the way through, I realized I kind of wanted everyone to be killed by an alien.

So there you go, writers, actors, and all artists everywhere. Build your world. Make it as complicated and fantastical as you’d like, but if you hope your audience will follow along, you must follow your own rules. Do not be tempted to go for an easy laugh or plot-point if it doesn’t follow the internal logic. If you do, your readers will lose interest and close the book.