I read 10-Science-Fiction-Movies-Every-Sci-Fi-Fan-Should-Watch and one commenter said Star Wars is fantasy, to which another asked why, to which I felt compelled to reply. It's an ongoing discussion I've had with many people, and surprisingly to me one that has made a lot of converts (I'm not used to scoring converts with my arguments, no matter how right I may be). Here's my comment:

• Star Wars isn't sci-fi in the same way Mazlow01 expressed Pitch Black isn't sci-fi: neither of them relies upon science, technology, or future society to tell their story. The settings, gadgets, costumes, etc. of both films are mere pageantry that make them look "techy" and sci-fi, but that's not what they are about. Sci-fi is fiction about science or technology and it's impact on people, and deals with scientific and technological concepts such that they cannot be extracted from the story without telling a different story. E.g. you can't have "I, Robot" without robots, but you can have killer creatures that only come out in the dark without going to other planets, and you can have stories about good vs. evil, rebellion against tyranny, and traditional morality vs. draconian law without spaceships, lightsabers, and Jabba the Hut. (In fact Lucas admits Star Wars is homage to the morality epics of 50s Japanese samurai films and American westerns, and to that end Star Wars has been called space western as much as space opera; it's about the moral drama, not the setting.)
• Now, why Star Wars is *fantasy* is because it relies heavily upon unexplainable (or at least unexplained) mystical happenings as a storytelling device. The Star Wars universe is no more plausible than Middle Earth, and Lucas makes no effort to make it plausible to our scientific worldview. The Force just is, and we accept it and what it can do without criticism, just like we accept balrogs and the power of the One Ring, because these features appeal to nothing but imagination to make them work. Science fiction, with the very intonation of "science", appeals to our understanding of the natural world to support itself. Science fiction portrays worlds that, given our understanding of the natural world, we have reason to believe could possibly be, while fantasy portrays worlds which we have no reason to believe could exist.

Lucas didn't try to make serious sci-fi with Star Wars. What he did was remake classic Akira Kurosawa films, which were themselves inspired by American western and detective stories, and dress them in the visual pageantry of a space setting. One of Kurosawa's best films, The Seven Samurai, was adapted into a great western The Magnificent Seven. Despite the radically different settings, neither The Magnificent Seven nor The Seven Samurai relies upon it's setting to tell it's story because the story can be extracted intact from each and injected into a new setting. Star Wars is the same kind of storytelling about epic themes that transcend the setting, and borrows heavily from Kurosawa's films, particularly the awesome Yojimbo and The Hidden Fortress. Lucas extracted great thematic elements from those films and injected them into a fresh and entertaining space setting, but just as Kurosawa's films were not about feudal Japan and Sturges' was not about the American west, Star Wars is not about the space, aliens, or technology displayed in it.

The hallmark of fantasy is that is uses a mystical setting or worldview to explain events, or rather that it invokes mystical features of the setting to avoid having to explain events. No one knows how Gandalf works his magic, how the One Ring corrupts, or why elves are immortal. These are just facts of Middle Earth about which readers/watchers are expected to suspend disbelief (and we do so happily). In our modern paradigm logical explanations about events in the world are derived from science, and these facts do not stand up to logical scrutiny because there is no science that supports them. This is of course perfectly acceptable storytelling as good fantasy doesn't claim there to be any logic or reason behind it's mystical events, so there is no reason we should seek logical or scientific explanations. Fantasy worlds are no our world, and they provide no reason to believe they even in principle could be our world.

The Force is 100% fantasy. Notwithstanding Lucas' pathetic midi-chlorian postulate, which was just a lame and misguided attempt to shore up the franchise with some sci-fi legitimacy, there is no explanation for the mechanics of the Force, and no scientific basis to believe it even in theory could work. The Force = magic, and magic is inextricably fantasy.

The hallmark of science fiction is portrayal of worlds not just like our own, but which could be our own, not just in principle but even plausibly given our current understanding of the natural world. Sci-fi takes the world as we known it and stretches it's principles to extremes, portraying worlds and settings that may be possible under extraordinary conditions or in the future. Fantasy doesn't bother starting with our natural world but rather reinvents the fundamental features of the world to suit the storytelling devices it wants to use.

Good sci-fi requires little suspension of disbelief because it portrays settings we believe are possible. Will there be spaceships and colonization of other planets? Yes, and portrayal of this does not require us to suspend our belief in the natural world. Will those spaceships fly around with the same physics as airplanes in atmosphere, and will they make cool engine noises? No, to accept that we must suspend beliefs we already have about the nature of space vacuum and microgravity, meaning to accept it in the film we must tacitly accept fundamentally different natural rules of the film world. Some literary license is of course acceptable and even most good sci-fi doesn't let natural verisimilitude hinder the storytelling, but look at 2001, the great tv series Space: Above and Beyond, and the new Battlestar Galactica series to see that consistency with the natural world doesn't have to hinder great fiction. Except for 2001 they still take a little license with sound effects (much less than Star Wars), but they portray zero-g inertia faithfully.

And finally sci-fi isn't a transcendent story just set in space or the future or an alternate reality, it is a story about space, the future, or an alternate reality, and how the science and technology in those settings affects protagonists. 2001 is not a story + aliens and AI, it is a story about aliens and AI and that story cannot be told without those elements. The Matrix isn't a love story or slave rebellion tale merely set in a virtual world, it's a story about virtualization and human-machine interface. The story of Star Wars can be retold without corruption in an American west or feudal Japan setting, does not rely upon the science and technology elements of it's setting, and therefore does not qualify as science fiction.