Neal Stephenson on "what is science fiction?" (something that I've often tried to define. he hits it right on.)
Fiction that's not considered good unless it has interesting ideas in it. You can write a minimalist short story that's set in a trailer park or a Connecticut suburb that might be considered a literary masterpiece or well-regarded by literary types, but science fiction people wouldn't find it very interesting unless it had somewhere in it a cool idea that would make them say, "That's interesting. I never thought of that before." If it's got that, then science fiction people will embrace it and bring it into the big-tent view of science fiction. That's really the role that science fiction has come to play in literature right now. In arty lit, it's become uncool to try to come to grips with ideas per se.