T Bone Burnett

But my point is these Civil War songs were gruesome. The hatred that's so bad in this country today, and for the past 10 or 15 years, bad as it is, is nothing compared to the kind of things people would write down and sing back in the Civil War.

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.