First off, if you missed Scott's last post, please check it out because it's a great one!
There has been a big hullaballoo in the science world because some researchers recently claimed to have found a bacterium that is able to substitute the phosphate in its DNA with arsenate. You don't really need to know those details, but suffice it to say a lot of people are skeptical. Another scientist wrote a blog post arguing the different reasons why the original research can't be trusted. She includes this great line, which I think applies to fiction writing (at least MY fiction writing):
"There's a difference between controls done to genuinely test your hypothesis and those done when you just want to show that your hypothesis is true."
For me, each story I write has some sort of "hypothesis" or at least a question that is unanswered when I start the story. My hypothesis for my novel Rooster, for example, was that the world could sympathize with a man who was seemingly unlikable. My hypothesis for Bread was that a man could reach such a low that self-sacrifice was the best solution for him.
I start out with a hypothesis, and the job I assign to myself is to test whether or not that hypothesis is true. To do that, I expand on my story, I let it progress in directions that feel natural or "real" to me.
I try not to force it.
But, sometimes, when I do force it--when I suddenly throw in a bad twist in the story or when I make my characters do things that are inconsistent with their personality--that's the point when I stop genuinely testing my hypothesis and start trying to show that my hypothesis is true. I see this sort of thing in a lot of mediocre books and movies, when there is some point in the story where I feel like the creator is suddenly just trying to get to the finish line. I sometimes use the word sincerity to describe this sort of thing. When a story is forced, it doesn't feel sincere to me. The writing suddenly become a manipulative device to try and show a hypothesis. I don't know if other writers feel this way, but it captures my thought process as I'm working through a story.
As I write these days, the biggest challenge I face is to keep from forcing my story, especially when I get near the end. I'd say I haven't succeeded in doing this yet. I need to keep genuinely testing my hypothesis instead of trying to show that my hypothesis is true.