SF as Myth

H. Bruce Franklin has a nice polemic on the prehistory of science fiction.

Anyone who wants to comprehend human affairs in the 19th and 20th centuries needs some knowledge and understanding of science fiction. But what is science fiction, anyhow?

Let's start by distinguishing it from other fiction. On one side lies fantasy, the realm of the impossible. On the other side lie all the forms of fiction that purport to represent the actual, whether past or present. Science fiction's domain is the possible. Its territory ranges from the present Earth we know out to the limits of the possible universes that the human imagination can project, whether in the past, present, future, or alternative time-space continuums. Therefore science fiction is the only literature capable of exploring the macrohistory of our species, and of placing our history, and even our daily lives, in a cosmic context.

...So my key definition is this: Science fiction is the major non-realistic mode of imaginative creation of our epoch. It is the principal cultural way we locate ourselves imaginatively in time and space.