There seems to be various definitions of what speculative fiction is, but listed below are a few of the common themes I pulled from them:
1. It can be any genre or any format (including art) which includes a “fantastical” element to the overall story/picture
2. Deals with the hypothetical or more commonly, the “what if.”
Many, not all, seem to agree that speculative fiction is not purely fantasy. Spec-fic (as it’s also known as) must be believable; in that this could happen. After all, you’re speculating, exploring the many possibilities of a given event or idea.