"Writing is never solid," writes Steven Savage in his follow-up take on the way the ideas you cling to in a story can just weigh you down, like so many rocks. His take is that you go where the story demands, not where the artifacts of your story are dictating you go.
This reminded me of how easy it is to confuse the elements or ingredients of a story with the actual themes or meaning of a story.
People assume that because a story has, say, criminals or police in it, that it's therefore a story about crime or the law. A movie like, say, Sidney Lumet's Q&A is actually about those things; a movie like 48 HRS. is more about the dynamics of a fractious relationship between two misfits than it is about cops or criminals or legal issues. (It's total coincidence both of those star Nick Nolte, by the way. One example led me to the other.)
Disentangling all this can be even tougher when you're constructing a story that doesn't have an easy genre label on it. Or one where you're taking something that ostensibly lives in a particular genre and you're trying to invest it with qualities that live outside of that container.
Good SF&F makes distinctions like this easy to parse. Clifford Simak's story "Condition of Employment" manages to be about two things at once: the way space travel is likely to be a lonely affair (the personal, human side), and the way such a thing could be exploited as a technical innovation (the SF side). The two sit side-by-side and enrich each other, and so the story manages to be about both of those things.
This is one of the dangers of using a story as a bottomless receiver for Neat Ideas. Authors sometimes do this as their first big outing — they go on a shopping spree and stuff the cart of their story with everything they can think of. (Another sign of amateurism: a list of thank-yous in the credits that includes dozens of authors, directors, bands, etc...) Sometimes they do this without lending any thought to what the thing is about, in part because they haven't gotten to that stage of their development where they can say what something is about without just running down the plot or reciting a laundry list of ingredients.
Let me relate all this back to Steven's point. If you know what a story is actually about and not just what it contains, and you're not married to the idea that one equals the other, it becomes easier to jettison things holding you back, and swap in things that can move you forward.