As I put it in another thread (http://lesswrong.com/lw/1ko/on_the_power_of_intelligence_and_rationality/) about how technology helps the development of science, "partly I think because technologies are easier to see clear relationships in and explanations for, than the messy, complicated real world", so I think fiction can help you to see more clearly relationships from the real world because the stories are less cluttered with irrelevant detail.

Also it can be hard to put knowledge into words, fiction can help you find the words for things you had already known sub-linguistically.