In what most of you probably hope will be the last of my posts about speculative fiction genres, I venture into minefield-strewn territory. Attempting to clearly distinguish fantasy from science fiction has resulted in countless internet flame-wars and convention rumbles:
The delineation has always seemed fairly obvious to me and, this being the internet, I must be right and anyone who disagrees with me must be horribly, hurtingly wrong.
I define science fiction quite simply as any speculative story that obeys the natural laws of the universe and whose premise is at least hypothetically possible. Therefore, such tropes as time travel, and interstellar space flight, while not practically possible might become so with the discovery of as-yet-unknown maths. The multiple spacial dimensions described by String Theory, for example might allow for things that are impossible according to Newtonian mechanics or Relativity. When known laws are broken, science fiction stories are obliged to explain how and why by coming up with plausible explanations.
Fantasy, on the other hand, freely violates natural law and invokes magic as a causative agent (notwithstanding Arthur C. Clarke's maxim that any sufficiently advanced technology is indistinguishable from magic), which requires little further justification. As long as the rules of the fantasy milieu are internally consistent, you can do just about anything you want, and the readers will buy into the premise.
So, according to the Robsonian Paradigm, simply setting a story in the future and with advanced technology doesn't make it science fiction. Star Wars is an excellent example of a fantasy adventure in space. It completely ignores the rules of physics: blasters go 'pew' in a vacuum, space ships are driven like racing cars, and parsecs are units of time instead of units of distance (though this last owes more to ignorance than intent, I think). Furthermore, it makes free use of magic - The Force.
Likewise, Dune ventures into fantasy territory with its spice-fueled magic. Dune could easily be rewritten as a traditional sword & sorcery fantasy novel without missing a beat. It is simply a fantasy novel set in the distant future.
Star Trek straddles the fence between fantasy and science fiction. However, the shakier elements of Star Trek probably owe more to a limited budget and interference by network executives than by Gene Roddenberry's intent, and intent is important so I think we can safely nudge Trek into the science fiction camp.
Despite the ambiguity of the fantasy and science fiction sub-genres they are a useful construct because, if you adopt my definitions, they let the reader know what they are in for. And as similar as the two genres may appear, many people love science fiction but hate fantasy, and vice versa.
They also allow us to use horror (which I discarded, in my previous post, as both as a genre and as a useful label), as a template applied to fictional genres. This template, which I call 'dark fiction' is one in which the examination of fear is central to the story, which may fit into any fiction genre. Thus we can have dark literature such as Heart of Darkness, which lacks any speculative elements, dark science fiction, which explores the terrors of the unknown (e.g. Alien), and dark fantasy, which contains supernatural elements that defy the known laws of nature (the vast majority of 'horror' novels). You can apply the 'dark' template to anything - even romance (what is scarier than love?).
This brings me, at long last, to the point of the last couple of posts: constructing a frame of reference to discuss the sort of stories - dark fiction, all - that I write. Over the years I've written stories of myriad genres: fantasy, science fiction, and non-speculative contemporary literature, but all of them have shared in common the theme of the dark nature of humanity. I pick at humanity's scabby soul. I pick at it until it bleeds. I can't help myself. I don't think I could refrain from morbidity if I tried; fortunately, I don't much want to.
Making this connection, identifying what all of my stories have had in common, was a fairly recent revelation and has led me further down the path to 'finding my voice' as a writer. This is something that eluded me for years, but by understanding what, why, and how I write has enabled me to consciously apply the 'dark' template, the template of my personality, to my stories, which has greatly improved the quality of my writing.
I think we've all, some time or other, been told something repeatedly without really 'getting it' until the 'aha' moment when we finally truly understood. There is a world of difference between knowing something and knowing it. Writers are always told that they need to find 'their voice,' but not how to do it. This is because finding your voice basically comes down to letting your personality show in your prose. How we do this differs for each person, so it is really a personal voyage of discovery. But when you do find your voice, it becomes like a template - a stamp that marks everything you write, whatever the genre, and makes it uniquely yours.