I am under no illusion that there exists a rigid dividing line between science fiction and fantasy, nor do I believe that a firm separation between the two is desirable or should in any way be policed. I am, however, of the opinion that sf and fantasy do different things--not necessarily incompatible things, but different nonetheless. These different things, naturally, tend to be erased when people make the claim, which seems to be popular nowadays (and maybe always) that there is no difference between the two related literatures, or that it is always and only futile or even harmful to make any kind of distinction between them, claims which are to me quite different, and much less tenable, than the less-sweeping claim that we need not try to enforce some mystical and totalizing distinction between the two. To say that, for example, Rendezvous with Rama and A Wizard of Earthsea have very different concerns, and are doing very different things, implies nothing about the existence or validity of, say, Dhalgren or any other work that fits comfortably into (n)either category.
I've avoided discussing fantasy here, mainly because in general I am much less drawn to it than I am to sf. As a result, I read and have always read much less of it, know less about it, have less of a grasp of its poetics--and I certainly am not equipped to discuss in any authoritative way what I feel these differences between it and sf to be. That said, a thought has occurred to me. Please don't take any of this as absolute; it is speculation merely. If it helps, feel free to throw it all into the subjunctive and put "I wonder if..." at the beginning of every sentence.
I wrote recently about the tension I find in sf between the realm of explication--and the forms explicaiton takes--on the one hand and the presence of the inexplicable on the other, a tension I find to be at the heart of pretty much any sf worth considering. Soon after writing that, I embarked on my first serious attempt to read Heidegger,* whose thoughts, when I feel able to grasp them, have only reinforced my interest in this tension. Meanwhile, I've been slowly making my way through Speculative Fiction 2012, a collection of online sf writing from last year in (goodness) book form, and so in the midst of all this thought about the inexplicable and the irrational I read Robert Berg's review of Tim Powers's novel On Stranger Tides. I have nothing to say about Powers, who I've never read (and am not likely ever to read), and I don't mean to pick on Berg, who aside from this one review I've never read either.** It's just that this was the piece of writing that got me started thinking all this. Because at one point early in his review, Berg writes: "Not only is his magic system brilliant, brilliantly worked out..." But I'll return to that in a moment; first, some more background.
*Starting slow, with the (genuinely helpful) collection Basic Writings and Timothy Clark's very friendly Routledge introduction to Heidegger.
**To be sure, judging from this review he and I have essentially nothing in common as readers, but hey ho.
Not just sf but the whole broad field that contains it, fantasy, and the overlap between them, is I think one that deals heavily and directly in a blending of the rational and the irrational (and at this point I must apologize for the imminently incessant repetition of these words and their various derivatives). "Pure" science fiction frequently thinks it can get away with "pure" rationalism--which is but one reason why I won't (ever) be reading the latest issue of Analog, the magazine that once published Vonda N. McIntyre's "Of Mist, and Grass, and Sand" but never would today.* And "pure" fantasy sometimes thinks it can get away with "pure" irrationalism--sometimes successfully (I think of some of Rachel Pollack's wonderfully illogical short stories), but more often falling into the unsolvable problem: if I can write anything at all, why write anything at all?, leading to endless accidental parodies of Kelly Link and equally accidental pastiches of Franz Kafka.** But the sf/f that people really care about, I would argue, falls somewhere in between, in the tension I identified in my earlier post.
*Would anyone? I'm less sure than I'd like to be.
**Who, as Gabriel Josipovici has pointed out, ran into precisely this problem himself in his attempts to finish the ultimately abandoned early story "Description of a Struggle," in the writing of which he had originally thought to grant himself total freedom; see Josipovici's essay "Kafka's Children," collected in The Singer on the Shore.
And so the important question becomes: what is to be done with this tension? What movement does it allow? Returning now to Berg's review of Powers, "magic system" is an innocuous enough phrase--indeed I believe it's a common one in writing about fantasy--and "brilliantly worked out" is just as innocuous; but I found they rubbed me the wrong way. In investigating why this might be, I returned to my (now Heidegger-flavored) thoughts about the rational and the irrational; I thought about the examples of explication giving way to the inexplicable that I gave in my previous post on the subject; I thought about other sfnal moments I love and that now seemed related, such as the glorious passage in Vandana Singh's "Sailing the Antarsa" where the narrator realizes that "All I can do is to practice what I did in the great forest: stillness. Stillness while moving at more than 50% of the speed of light..." And it occurred to me that all this may be a pointer as to why I find myself drawn more to sf than to fantasy: for while the best sf brings the inexplicable to the world of explication and finds the cracks in rationalism through which the irrational (which never really went away) returns, fantasy, perhaps, tends to do the reverse: it brings reason to the irrational, puts magic into a "system." And this is a movement I find, well, distasteful at best.
Thinking further, I realized that those few works of fantasy that I love as I love sf tend to face this head on, as a problem--take for example Pollack's marvelous novel Unquenchable Fire, which is precisely about an irrationalist revolution long since ossified into order and hierarchy (and a creeping return of rationalism), and the dreadful situation this creates. And my favorite works that blur the distinction between fantasy and sf, say Ursula K. Le Guin's The Lathe of Heaven or Hayao Miyazaki's film Nausicaä of the Valley of the Wind or many of H.P. Lovecraft's stories, very often place themselves in similar territory (in, of course, their vastly different ways, to their vastly different ends).
To repeat: I don't actually read much fantasy, and I could easily be wrong; and I am not attempting to dismiss the field of fantasy entire. But looking back on what fantasy I've read and disliked, it seems to me that this is the greatest part of my problem with it: that it seeks to order those parts of life best left unordered, to explain what cannot be explained, to brilliantly work out systems for what cannot be systematized--or worse, what can be systematized, but only at a tremendous cost.
(On the other hand, it might just be that I like spaceships and aliens better than castles and dragons. YMMV, as they say on the internet.)