Full disclosure: Short form fiction and I have never seen eye-to-eye. There’s a knack to it that I’ve just never quite seemed to get the hang of. There’s this gap between ‘self-contained story’ and ‘obviously part of a larger novel’ that I can’t quite seem to cross.
Part of it, definitely, is about complexity. Short stories and novels force the writer to approach complexity entirely differently. From one perspective, a short story cannot possibly be as complex as a novel, simply because it doesn’t have time to be. A novel can set up multiple interwoven themes and explore them from several angles. Indeed, it sort of has to, or it starts to sound thematically flat or one-note. Whether this is a detriment to a reader enjoying the story is up to the individual reader, of course, but the closer a novel gets to single theme, the more it starts to sound like a Message Story, or at worst, propaganda.
By contrast, a short story, except in the hands of a very skilled author, usually has space to explore one theme, approached from a few angles at most.
Of course, it is preposterous to say that a short story must therefore be shallower or less meaningful than a novel. In fact, reputation says the opposite: short stories have a reputation for being thematically dense, while novels, except in particular genres, have a reputation for being frivolous entertainment. Mostly, this comes from the fact that the number of people who read literary and classic fiction recreationally is much smaller than the number of people who read only genre fiction recreationally, and that short stories tend to have a niche audience at the moment, so the short stories most remember will be from school, and perhaps from a few famous anthologies, which tend to attract more literary fare. Thus, short stories have become relegated to the arena of experimental fiction and deep reflections on the human condition.
So, obviously, short stories are able to convey a lot of depth and meaning, even a comparable amount to novels. But they do require an entirely different approach. While novels gain depth by examining the interactions of a few different themes and approaches, short stories are usually better served by choosing just one theme and either exploring one angle (or a very few opposing angles, depending on the length of the story) in greater depth.
Also, the ‘rules’ for writing need to be applied on a different scale. For novels, one of my personal favourite guidelines for editing is that every scene needs to do two things to further the story. For short stories, apply that to every sentence, and especially every line of dialogue. A short story still needs a complete plot, unless it is part of a series, but there must be fewer plot elements.
This is where movies must stop trying to be television shows. A movie is not a novel, it is a short story. Too many plots, too many themes, and too many interlocking elements will make the story feel bloated, chaotic and messy. Movies are better off emulating the short story’s hyperfocus, rather than whatever it is they’re trying to do at the moment.