Robert A. Heinlein

Political tags - such as royalist, communist, democrat, populist, fascist, liberal, conservative, and so forth - are never basic criteria. The human race divides politically into those who want people to be controlled and those who have no such desire.

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.