It is the distinction between those fans who read texts only on the level of in-show content on the one hand, and those who read texts according to their codes of representation on the other. [...] When Doctor Who swaps actors, it has to be written into the text on the level of content, it has to be rationalised and explained. The problem with this attitude (widespread in SF, I'd say) is that it treats us, readers and viewers, as if we are all as idiotic as Hugh Laurie's Prince George at the Theatre ('Look behind you Mr Caesar!').(If you watch the deleted scenes of Buñuel's That Obscure Object of Desire there are actually eleven different sequences in which one of the two actors playing Conchita gets metamorphosed into the other by means of full brain emulation and resleeving in vat-grown clones, glittering jade regeneration beams and so on. The original cut is 43 minutes longer and a far better film. At least it makes sense. In terms of 90s sitcoms, Roseanne makes deft use of a service hatch in the fourth wall to note that the actor playing Becky has changed, and Game On gets meta-meta with that. OK).
I guess there may be two things here. (1) The main one is about how SF communities can be oddly matter-of-fact and literal-minded -- about those moments when we suspend our suspension of disbelief, and raise objections which are already (obviously, you'd think) sorted out, at the level of representational convention, simply by fiat or by tradition. Stories teach us how they should be read. Even BYOGI stories (Bring Your Own Grid of Intelligibility) charge corkage.
Because of the nifty features of any fiction is that you can just make stuff up. Perhaps SF creators spend too much time catering to fans with narrow and permanent ideas about what you can and can't just make up, and perhaps our SF would be more fun, fascinating, funny, beautiful -- even more moving and wise -- if we didn't. It would probably be easier to write, anyway!
The stereotypical hard SF fan is one example. Things you can't just make up: ballistic coefficient, air drag and propellant to payload mass ratio. Things you can just make up: episodes and impulses of the human heart.
(2) Then again, there's something quite appealing about the ornery, persnickety quality of some hard SF and of some worldbuilding or worlddemolishing. The second drift, perpendicular to the first, suggests that maybe it should be way harder to write SF. Perhaps even impossible (see note).
I can imagine people who would not regard the second as an inconsistency of worldbuilding (based upon doesn't mean same as; no reason why this imaginary land might not be a monarchy; Neptune a recognised maritime mythic figure; and so on). Nonetheless, I am these days more put out by the second inconsistency than the first.So there's a hint of a principle of consistency based around cultural logic, around codes of representation, not just content. I'm not 100% sure, but I think this means: not just "what happens in the story," but also what the story is about in a very broad way: its themes, its contexts, its precedents, its analogues, its affinities, its intertextuality etc. And also how it is a story, how it is about whatever it's about: its rhetoric, its devices, its discursive landscape, its interpellations, its literary, cultural and sociological forms, etc.
Because when you make stuff up, you never just make stuff up. It comes from somewhere, and it goes somewhere. No matter how original your thought, its ingredients already exist elsewhere. No matter how dry your sponge, it is totally soaking with the tincture of the honey-lipped wordsmiths who have babbled before you and go on babbling still. Similarly, it's never just you who makes it up. Sentence by sentence, you minutely adjust which vast, complicated team you are on. Every linguistic or imaginative decision takes up innumerable minuscule ideological stances, makes innumerable individually futile allegiances.
So perhaps -- just as hard SF creators scrupulously include the real laws of nature (to our best knowledge) in their fiction, even when they are not convenient -- there is (or could be) a kind of SF creator who scrupulously includes the history and culture which we really happen to have (to our best knowledge) even when that is totally awkward. I don't think Adam Roberts is really advising that every particle of SF should be in constant vigilant harmony with her countless sisters in citation. But the extreme case is intriguing. What might it look like? Every existing field of study, and new bespoke fields, treated with reverence sometimes given to physics, engineering, chemistry and biology? Or How to Do Things With Science Fiction? -- or rather, SSA (Science Speech Acts) with some important part of an audience -- King Claudius in Hamlet or Hugh Laurie -- driven by resonant verisimilitude to reveal something? Or Alexis de Tocqueville photo-bombing every SpongeBob SquarePants lunch box? Part of what I like about SF is that it can forget it is fiction, and try to be science. I'm still trying to work out what it might be the science of.
Note: Or perhaps, impossible for one person? I'm interested in continuity-building as a/the function of criticism. Normally you might suppose a reader suspends disbelief, but a critic does not. Perhaps the fan who fails to entangle themself sufficiently intricately into the text's codes (and so makes inappropriate interruptions etc.) could also be the critic who is capable of thinking and writing about a text which is "active," a text in which they are partly still immersed. The text's world is still real -- but its codes can be selectively shut down or stunned to allow the reader wiggle room to compensate for what it lacks?