speculative fiction (idea)

In 6th grade, the reading instructor started a unit on speculative fiction. He gave what I consider to be the one of best and most useful definitions of it:

Speculative fiction is fiction that asks the question "What if..."

This definition envelops alternate history, plain science fiction, hard sf, soft sf, horror, and fantasy (both alternate world and sword and sorcery) quite readily. It could arguably be pushed to envelop historical fiction and most other fiction, but the "What if..." involved might get quite unwieldy. Speculative fiction tends to push on concepts of reality — or focus on what is essential about our own humanity. The term appears to have been coined by Robert Heinlein, based on a brief search of that fountain of knowledge, Google.

Some examples of What if:

• What if a human was raised by aliens with a vastly different perspective on things and then brought home?
• What if a lost colony had to contend with space fungus?
• What if the all that nifty baroque 19th Century tech were developed a bit further?
• What if the universe was a silly place? (I could come up with a better question for that one, but I like the question I have too much.)
• What if the gods did play dice with the universe?