Piers Anthony

I never do a full outline, and if I did, I would not feel bound to it, because the view from inside a scene can be different from the view outside it. But neither do I just start writing and see what happens; I am far more disciplined than that.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.