Robert J. Sawyer, the sf writer, has a rather tiresome post insisting that science fiction is rational, whereas fantasy is not. He actually argues that the only reason for any market overlap is due to Ace Books pirating publishing Lord of the Rings in their sf line. That sf and fantasy were mingling in fiction magazines (and elsewhere) for a generation or more before this epochal event is a fact that passes under Sawyer’s radar: not a powerful instrument, it seems.
Preferring sf to f is a point of view (though not mine: I like both) and there are certain distinctive features to each genre: robots in sf, golems in fantasy, etc. But rationality is not exclusively or particularly a feature of sf; it is essential to fantasy, as Tolkien pointed out a decade or so before he set out on his mission to destroy Americo-Canadian science fiction.
Sawyer’s point rests on his assertion that fantasy deals in things which cannot happen, whereas sf deals with things which can happen; that’s why sf is rational and fantasy is not. Putting aside all the impossible things that sf routinely proffers us with a straight face (like the dimension-hopping highly intelligent Neanderthals RJS writes about), let’s consider the premise that it is rational to consider only those things which one knows to be possible.
This might be a reasonable proposition if we knew absolutely everything which is possible and everything which is impossible. But we don’t. Arguably, we can’t, but in practical terms we never will. To be rational in the real world is to acknowledge the limits of one’s knowledge, to entertain the possibility that everything you know is wrong, or at least some of what you know is wrong. The inability to confront this existential reality is not a sign of rationality; it is a symptom of dogmatism.
“Counterfactual thinking” is another way of describing the feature of fantasy which RJS erroneously calls irrational. Counterfactuals are essential to human psychology. They have an important place in philosophy and science and history. Someone who could not engage in them would be utterly shut off from the unknown possibilities that life offers.
[Edit: fixed a bad link. Bad Link! No ocarina for you!]
[I copped the link to RJS’s blog from Paul Jessup.]
[Another theft from Paul Jessup: There’s a fell-off-my-chair-funny web-comic about the Sawyer kerflufflet at Steve Wilson’s My Elves Are Different. I mention this somewhere in the comments, but after sagely considering the question for roughly 5 milliseconds I decided that My Elves Are Different needs to be exalted to the skies. And lifting the link up from the comments was as close as I could get.]