«Ask the man in the street what science fiction is and he'll probably say something like Atwood. He'll mention aliens, robots, spaceships and ray guns; he may add that it is set in the future. Clearly, however, this isn't a sufficient definition.
What this does do is throw a bit of light on that classic "it's not science fiction" argument. If your idea of science fiction is defined by formulaic plotting and stereotyped characters then just because you have used spaceships and aliens you don't want people to think you can't write. Unfortunately many literary critics have an tendency to assume that anything that contains spaceships and aliens must also have the aforementioned formulaic plot and stereotyped characters, hence the eagerness of Atwood et al to distinguish themselves from the despised herd. But just because some dogs have spots, it doesn't follow that everything with spots is a dog.» _
Cheryl Morgan makes the case for genre as a process rather than a category. Worth reading.