No matter how carefully you have written a story, there are going to be some elements of it that make significantly more sense to you than they would to anyone else, and elements that escaped your cause-and-effect analysis while writing. It's a simple enough error to make. As the product of your own imagination, you can easily order and rationalize the contents of your own work. It's important to make sure that logic didn't take a brief holiday in your imagination, momentarily sidelined by the thrill of creation and the progress of events as you wished to see them unfold.

Logical mishaps in storytelling are a fast way to break the suspension of disbelief in a reader. We're not talking about illogical behavior in context, but fundamental problems with story, setting, and characterization that do not conform to the internal standards of the work. This article examines a few of the most common pitfalls when it comes to maintaining logical integrity, in order to give you greater insight into spotting them as you review your own work as well as how to see them coming, and thereby avoid tumbling into one even as you write.    

Every setting comes with an implicit set of rules that govern how the universe works. These may be identical to our own, slightly, or even radically different, but they must remain internally consistent. One step beyond that consistency is that the rules of the setting must be reasonable to the reader. A reader does not have to like or agree with a setting, but they do need to find it plausible and functional, or they will be adrift in a meaningless environment and fail to enjoy the story.  

Your characters are bound to be exceptional, and do exceptional things, but in order for them to seem special you have to protect the rarity of what they are and do. We recognize that having six fingers on each hand is a very unusual circumstance in our world. If, however, we encounter a high frequency of six-fingered hands in a story, then we have been informed that we are dealing with a universe in which that is not uncommon at all. If you want your character to be exceptional, you absolutely must make sure of the standard they are excepting, and stick to it.

Do not create a supposedly rigid boundary just so that you can swiftly break it. Don’t make a certain outcome impossible, and then follow through by having it happen anyway. It renders the boundary meaningless to subvert it in this fashion. Push it, bend it, sidestep it - but don't break it. Make that boundary important.  

In science fiction, keep tabs on your really big numbers. They're easy, and they're dramatic, but we don't always appreciate how big they are. It's crucial to think about the ramifications of those really big numbers. They're needed when talking about distances and sizes, but did you really mean ten thousand spaceships, crewed by ten thousand apiece, the size of cities? Or did you mean to say "A lot"? If a number is too big to effectively visualize, it loses meaning.   

In fantasy, keep tabs on your really small numbers, most notably the number one. If there is only one solution, only one object associated with it, and only one person knows where it is, you have invented the express speed train of contrivances.  

Keep your character interactions proportionate to the setting. While your characters may be the most important thing happening in your story, they are not always the obvious center of their own universe. It can be easy for them to become more famous or notorious than actually makes sense.  

Never let your characters get away with doing things just because you want a particular result. Convince them. For example, when bringing characters together, or separating them, think hard about why those transitions occur and what makes them rational. People behave irrationally, but when they do they are irrational for rationally comprehensible reasons. If "We should split up." has come up in conversation, pay close attention to why anyone might agree to this almost universally unwise proposal.  

A character's emotional response to the situation in front of them should always reflect that characters background, experience, and personality. A sudden well of stoicism has to come from somewhere. People do overreact and under-react to situations, but they do so consistently and they do so for reasons rooted in their psyche. Wildly unpredictable emotional response is a psychosis, not just a mannerism. Get to know your characters as people and pay attention to when they should or should not be shocked, excited, or bored. Also, don't forget to show the reader those reactions.  

Pay attention to what your characters do or do not know, and why. It can quickly break a setting if the characters are unbelievably clever or obtuse, have thin excuses for being knowledgeable, or present information to one another in a way that is clearly more for the reader’s benefit than sensible for the characters.  

Dispute and conflict may often be rooted in ongoing misunderstanding, but these misunderstandings must be carefully nourished by a writer. Consider why people are not communicating, not getting their information or feelings straight. Does the romantic pair automatically assume the worst and most dramatically horrible cause for the actions of their partner, and immediately become inconsolably upset such that they will not even discuss or attempt to clarify the situation in any fashion? Despite being the plot of 75% of all romantic comedy films, this is an irrational pretext and sloppy storytelling. Picking up a book on basic psychology, observing people in their natural habitat, and reflecting on your own experience are all very good tools for learning how to properly nourish a misunderstanding between characters without resorting to contrivance.  

Pay close attention to the physical, social, and ideological environments of your story and how those impact events. Just as with character's actions, events unfolding march to the beat their environment's drum. Always ask yourself why something has happened. The characters may not know, the reader may never unravel it, but it should have causes that you understand and apply, or it will not proceed in a logical fashion. Why did the cave collapse just then? What caused the spaceship to veer off course? If you don't know the answer, events will unfold in a random and coincidental fashion which is unsatisfying and difficult to follow.  

Be complicated. Single-facet societies, environments, and characters are very easy to grasp but hard to believe in. A world is not composed of one sort of person, one climate, one nationality. Even the most homogeneous earthly cultures are deeply complex. No empire in history has ever brought its constituent parts into uniformity. A veneer of similarity may be imposed, but differences do not fade away, they evolve.  

A useful exercise is to watch any episode of your favorite long-running science fiction program. Consider why the new and exciting environment for the adventure-du-jour would utterly fall apart under intense scrutiny. Now, because you love your favorite program, think about how you rationalize that setting sufficiently to enjoy the show anyway, holes and all. Compare those rationalizations and allowances to your perceptions of your own writing. Do you find yourself making similar excuses?

The best stories are the ones you can believe in, in worlds you can visit in your imagination, with characters you know like old friends. Reality as we know it is rich with detail, nuance, and complexity. The successful storyteller has competed with the persistence of that reality, and won.