This is a good post (you have to scroll past the unrelated and intemperate rant about bans on smoking).
Summary: SF which is a genuine imaginative attempt to explore a possible future, perhaps as diffrent from us as can be, is just as valid as SF which illuminates some truth about us here and now. He doesn't say so but this probably applies to fantasy too
(all the rest is Ken McLeod's words)
In articles and interviews which I've ruthlessly recycled as talks at SF conventions, I've put forward a by no means original thesis that SF can be more illuminating about the time of its writing than about that of its imagined future (but now I've changed my mind...)
Besides, that whole argument gets uncomfortably close to a capitulation to the oft-heard claim (which deserves to become known as the Atwood Defence) that what is really interesting and important about SF just is its contemporary reference; that some novel that might superficially appear to be SF (because it's, say, set in the future after some genetically engineered plague has wiped out most of the human race) isn't really SF but satire, and really about the present, and not related to that vulgar stuff about rockets and rayguns and talking squids in outer space, and therefore may deserve serious consideration and can be safely opened without risk of releasing alien germs to which normal Earth readers have no natural immunity and which could sweep through the entire literary community and all die, oh, the embarrassment.
So, with space helmets on, brass bras brightly polished, and phasers set to stun, let's boldly go in search of SF that really is about the future, and whose contemporary reference is reduced to as close to a trace element as humanly possible.
Interestingly enough, the division between what I'll boldly call pure SF and SF-as-satire cuts across, rather than between, a lot of the themes and tropes and subject areas of SF. Let's start with the most obvious: stories set in the far future. Clarke's The City and the Stars, already mentioned, or Olaf Stapledon's Star Maker are undoubtedly novels which, while inevitably of their time, are not fundamentally interested in or secretly about their time. They are about the far future of humanity and the universe. But what about Michael Moorcock's 'Dancers at the End of Time' stories? They are about an opulent, irresponsible decadence, about ennui, about fin de siecle, rather than the literal end of time.
On to the second most obvious: post-apocalypse stories. It seems to me that Walter Miller's A Canticle for Leibowitz is a story that can be understood without much reference to the time in which it was written, and gains little from applying a knowledge of that time to it. It looks at a post-catastrophe recovery of civilization sub specie aeternatis. The closest it comes to contemporary comment is in its final section, set a thousand or so years in the future, and in the eerie sense that section conveys that our civilization is a post-catastrophe recovery civilization, as indeed it is.
Robert Heinlein's Farnham's Freehold, on the other hand, is so embarrassingly about contemporary concerns, as refracted through the nastier parts of Heinlein's mind, that to discuss it is to push at the fallout shelter's open door and let in all kinds of toxic and radioactive stuff....
(rest of rant snipped out of sheer weariness)