Science fiction begins at the moment where science ends, and then you can go on and build on what is known. Therefore, science fiction is getting more and more difficult to write because science develops so fast that the science-fiction writer has difficulty coping with it. This is one reason why there is less and less technological science fiction written because technology has overtaken it.
I think a lot of science fiction does exactly that, 'what if' and then you propose a social change, or a physiological change, or a physical change in the world and then pursue it, like a thought experiment, pursue the consequences.
Fantasy changes the world deliberately, allowing impossible things which science fiction at least pretends not to allow. ...Then you just follow out, you just follow the fictional enterprise like any novelist, it seems to me, and the more detailed and accurate you are, the better the book will be. And of course, the tricky thing about imaginative fiction, both science fiction and fantasy, is the coherence of the imagination, because you are making a whole world out of words only. It's all made to hold together.
What do you think? Do you agree? Disagree?
Stay tuned tomorrow for more Le Guin on fiction.