Defining Science Fiction is not all that difficult. It's a genre, not a setting. SF deals with certain themes - namely the effect of science on what it means to be human. A story set 100 000 years ago featuring mammoth hunters could easily fit into the SF genre (and does) so long as it discusses what it means to be human in the face of scientific progress.
By that definition, by the accepted definition of the genre of Science Fiction, Star Wars is most certainly not SF. It's fantasy. Setting does not define genre whatsoever. The fact that Star Wars has robots and blasters doesn't matter. It's not SF because it does not, in any way, relate the plot to the development of technology.
You can reskin Star Wars as fantasy pretty easily. Same as you can reskin original Star Trek as Western. Later Star Trek started becoming more solidly SF, but the early stuff barely qualified.
The problem comes when people try to define genre through setting. That's not how you define genre, generally. It makes a fairly good starting place, but, it's plot and theme that defines genre, not location and props.
I don't buy it.
The problem with defining it as "the story is resolved through technology" or "the effect of technology on what it means to be human" is that the terms and ideas being used there are just too vague. For example, how do you define "technology" in this sense? In many fantasy settings that feature magic, magic is treated like a form of "technology", and stories deal with how the existence of magic mold culture and change history (the
Wheel of Time and
Heralds of Valdemar series might be good examples of this). In fact, the basic premise of "how does X affect mankind" is probably far broader than the entire scope of Science Fiction. Science fictions stories that deal with the impact of technology upon mankind are just that kind of story, given a Science Fiction setting.
Besides, if you use that logic to say Star Wars is not Science Fiction, then several other major works of science fiction would also be disqualified. For example, the
Dune series really is not focused on technology at all. The technology is just setting, while the main story is built around political maneuvering and the growth and development of a messiah figure. Similarly,
2001: A Space Odyssey also does not use technology as its central story. It is mainly preoccupied with human contact with an unknown force. The entire interaction between Dave and HAL could just as easily been an interaction between two people; the fact that one was a computer is mostly just window-dressing. I have not read the book myself (I have only seen the movie), but the entire premise behind
Contact is the idea of human contact with a an alien life-form. Again, the technology is irrelevent (and in the case of Contact, it is just a magical plot device that is not even understood by the people involved). The real story is about curiosity and faith, not science and technology.
Anyways, you claim that your definiton is the "accepted definition", but I have to ask "by whom"? Certainly not bookstores, I know that. They don't even treat Science Fiction and Fantasy as different at all... Certainly it doesn't seem to be the definition I see used in common discourse. When someone says "Science Fiction", they usually mean "robots and spaceships", not "cavemen learning how to use bows".
Also, if Science Fiction has such a clear definition, then what is the equivalent definition for Fantasy? These are two terms that always go together, serving as two sides of the same coin. If you want to seperate them at all by genre boundaries, rather than setting boundaries (where the line is fairly distinct), you need to give a good definition. If you can make a claim that Star Wars is Fantasy, but not Science Fiction, what definition are you using other than "it is kinda like Science fiction, but it doesn't meet
my definition, so it is Fantasy"?
