““I will define science fiction, first, by saying what sf is not. It cannot be defined as "a story (or novel or play) set in the future," since there exists such a thing as space adventure, which is set in the future but is not sf: it is just that: adventures, fights and wars in the future in space involving super-advanced technology. Why, then, is it not science fiction? It would seem to be, and Doris Lessing (e.g.) supposes that it is. However, space adventure lacks the distinct new idea that is the essential ingredient. Also, there can be science fiction set in the present: the alternate world story or novel. So if we separate sf from the future and also from ultra-advanced technology, what then do we have that can be called sf?””
