Metaphor level
In his essay "About 5,750 Words," in The Jewel-Hinged Jaw: Notes on the Language of Science Fiction, Delany talks about the "subjunctivity level" of phrases like "winged dog" in science fiction. The general idea is that there are phrases that are to be read as metaphor in literary fiction, but are to be taken literally in sf. (I've recently wondered if that explains part of sf's appeal for those of us who are unfortunately over-inclined toward taking things literally.)
One consequence of figurative-sounding phrases being more often literal in sf is that in an sf story, it can be hard to use figurative language without running the risk of sounding literal.
That probably didn't make any sense; I'm still waking up. Lemme provide an example:
The boy vanished.
In literary fiction and in most sf, that sentence could quite easily refer to a boy rapidly moving away from the viewpoint character, for example by running. But in some sf, it might mean that the boy suddenly winked out of existence (for example by teleporting or being vaporized), or disappeared without moving (for example by turning invisible or clouding the viewpoint character's mind, or by having been a hologram in the first place, or by turning into mist or an ant).
And so it seems to me that sf authors should be careful with such metaphors, especially at the beginning of a story when the reader may not yet be sure what the rules of this particular sfnal world are. It's fine to use such metaphors; just be aware that a reader reading them may not be sure for a while whether you intended them literally or not.
The same goes for words like "exploded," btw, which even in literary fiction might be literal. But a sentence like "He exploded with rage" is more likely to be literal in sf than in literary fiction.
