"It [a novel] should be beautiful, and powerful, but it should also work. It should have something in it that enlightens; something in it that points the way. Something in it that suggests what the conflicts are, what the problems are. But it need not solve those poblems because it is not a case study, it is not a recipe."
-Toni Morrison, "Rootedness: The Ancestor as Foundation." from What Moves at the Margin
In her essay, Morrison discusses the role of the novel through history and what it means to African-Americans in particular--as a tool to show how to behave. Jane Austen and her novels of manners show that if you behave properly and true to yourself, you get the hot man and the big, stinky riches at the end. Books like Madame Bovary tell women that if they are promiscuous and devious, then suffer the consequences. I'm just using the most obvious examples, Morrison makes her point in a much more subtle and artful fashion (which is why she's the mentor). But the point is pretty much the same: novels have traditionally been used as a behavior pointer...not a self help book, but a presentation of cause and consequence. Nowadays, I think that's still true, but the writing has become slightly more subtle.
Multiple writers have talked about the 'What if' question(Thank you, Stanislavsky for teaching actors this mythic phrase) that helps them come up with a situation. "What if...an asteroid hit the earth at the same time a couple was about to get divorced?" "What if...a kid comes into a school with a gun but the clown scheduled to show up in the first grade classroom stops him?" From these kinds of questions, you begin developing a novel. But the avenues you choose make the difference between a novel that works in a beautiful and powerful way and one that just preaches at you.
Depending on how you present the problem in the first asteroid/divorce example, the novel could read like a cosmic anti-divorce punishment straight from God. The clown stopping the gun-toting kid could read like all people need to go to clown school to be true negotiators. Now, this 'points the way', like Morrison suggests the novel should do. But I don't think she meant to preach at people. That's what pundits and, well, preachers are for.
I say that if you take the 'What if' question that you start with and explore it, then the novel will point its own way. Does the asteroid landing in the couple's backyard force them to act as a team for the first time in years? Does it kill one of them and the one that's left have to deal with guilt/consequences? Does the clown represent a wholesome kind of humor that can heal, vs the teasing kind of humor that will drive a kid to kill? Or is the clown so frightening that the kid is 'scared straight'?
Our job as writers is to pose the problem, ask the question, and then let the novel grow from that--the direction will choose itself. And it's also our job to look outside our own opinion and try to include that, we have to approach the problem from all directions as best we can. Again, approach the problem, not the solution from every which way. Various solutions will present themselves within the course of your particular novel. So the solution for that one situation will be honest within the novel...but not necessarily in real life.
I think that some writers need a lot of novels to truly explore a problem that's close to their hearts. Hence why there seems to be a lot of repition among certain writers' works. They haven't approached the problem enough to feel satisfied that it was explored.
Pose the problem, ask the questions. It will point its own way.