The Encyclopedia of Science Fiction points out that the sub-genre of science fantasy has never been clearly defined. The label first became widely used after many of these stories had been published in Pulp Fiction magazines, where authors attempted to merge the techniques of sci-fi with the world of fantasy. One of the ways in which science fantasy has been broken down is as the third level of science fiction, which also includes hard sci-fi and soft sci-fi.
In hard sci-fi, science or technology is central to the plot and all key elements of the story are explained using methods that comply with our current scientific knowledge including: scientific laws, theories and constraints. Soft sci-fi has similar elements but is not as rigidly scientific, and technology used may, or may not, have only a vague explanation. The scientific elements of the stories also include ‘the soft sciences,’ such as sociology and psychology. Like hard sci-fi, all elements in the story are entirely possible. Science fantasy includes the same elements as hard and soft sci-fi, but mixed with magical, or supernatural, ones. Parts of the story may also be explained using science which would not be possible, given our current knowledge.
There is often only a slight difference between soft sci-fi and science fantasy. Science fiction with religious or spiritual elements, involving miracles, angels, demons, and deities, often falls in the science fantasy sub-genre because their existence cannot be proven using scientific methods. Some of the other categories which include science fantasy are:
This is a subgenre of both science fiction and science fantasy, which interjects old technology into a futuristic setting.
Sword and Planet
These stories can be determined by the inclusion of an outdated social system, run by the aristocracy, and gallant swordsmen.
These stories are set primarily on a single planet, and uses the scenery, the natives and their cultures to create sci-fi elements which are rationalized using fantasy. A modern example of this is Avatar which appears to be mainly science fiction, with its inclusion of interstellar travel, cryogenic sleep and an alien culture. The new culture’s spiritual connection with nature, along with the flying dragons and floating mountains, serve to introduce the fantasy elements to the story.
Dying Earth and Post Apocalypse
These stories describe realms that have moved on, or are moving on, from the norm, and often include elements of both the future and the past.