Noam Chomsky

When General Allenby conquered Jerusalem during World War I, he was hailed in the American press as Richard the Lion-Hearted, who had at last won the Crusades and driven the pagans out of the Holy Land.

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.