Speculative Fiction... Isn't it all Speculation?!

Ok, Speculative Fiction... Do you know what it is? I've never really paid attention to the term, but there it was when I recently tried to define Margaret Atwood. She's not quite science fiction, but her world is NOT what we normally encounter. BUT, it could be...

Most people refer to speculative fiction, a term coined by Robert Heinlein, one of the greatest science fiction writers of all time, as belonging to science fiction, fantasy and horror, but it doesn't necessarily have to be any of those. What is does have to be is a kind of what if scenario. The Hunger Games is a good example. It's not what you'd normally consider sci-fi, but it's something not quite of this world. If things were just a little different in our present day, The Hunger Games could be plausible. Like Dystopian fiction, these worlds, plots, characters, could be a reality if things were tweaked just right. But wouldn't you say EVERYTHING is "Speculative"? Fiction is just that - fiction, and the author tries, and mostly succeeds, to make us believe that the story is plausible.

What do you think?

P.S. Some popular books referred to as "speculative fiction" ...

The Hobbit by Tolkien , The Giver by Lois Lowry, 1984 by George Orwell, The Road by Cormac McCarthy, and even the Game of Thrones by George R. R. Martin.