Tony Dungy

You may not win the Super Bowl. Your kids may not go on to be doctors and lawyers and everything may not go perfectly. That doesn't mean it was a bad plan or the wrong thing. It's just like a football season. Everything's not going to go perfect.

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.