I think that science fiction is not only a genre but its own class of story telling, meaning that the very way the story is written and evolves is different from most others. They have their plot, usually involving other world travel, past travel, future travel or really a journey to any other un-ontainable place in our society, but what makes them unique and have that element of science fiction is the way they comment on humanity. Science fiction films take a human element, apply it to the impossible and then proceed to comment on humanity. Most films take the viewpoint of humans when commenting on humanity, science fiction allows us to improve because we are being critiqued by characters and situations that we cannot relate to, it makes us more keen to the message rather than just the entertainment. Of course the entertainment is there as well.