Accordingly, the borderline between fantasy and science fiction is blurred, and many bookstores shelve science fiction and fantasy together. There is a substantial overlap between the audiences of science fiction and fantasy literature, and many science fiction authors have also written works of fantasy. Fans often nominate works of fantasy for SF awards such as the Hugo and Nebula, clearly indicating a substantial overlap among readers.
Indeed, it can be argued that science fiction is simply a modern form of fantasy. According to this view, the elements that would previously have been presented as fantasy (e.g., magic, shapeshifting, divination, mind-reading, fabulous beasts, and so on) are rationalized or supported through scientific or explanations such as marvelous devices, mutation, psychic abilities, aliens, etc.
This definition is resisted by some scholars and writers who attempt to define the genre's aspects more sharply, and advocate an aspiration to present a world without mystical or supernatural forces. For example, in such works as Metamorphoses of Science Fiction, Darko Suvin emphasises a cognitive element in SF. According to Suvin, the purpose of science fiction is to introduce scientific or technological novelties in order to create narratives that enable us to perceive everyday reality at a reflective distance. He uses the term cognitive estrangement to label this effect.
Some SF clearly exhibits this aspiration, but not all. As a result, some theorists are able to emphasise the difference between SF and fantasy, while others emphasise continuity. It is also common to see narratives described as being essentially SF but "with fantasy elements." More recently, the term "science fantasy" has been increasingly used to describe such material.
Science fiction and mainstream literature
Science fiction can overlap with more mainstream fiction.
If the society, the person, the technology, and the scientific knowledge base in the story are all drawn from observed reality, without much detail about the scientific aspects, the story may be classed as mainstream, contemporary fiction rather than as science fiction, like Marooned by Martin Caidin, or virtually all the novels by Tom Clancy. If the characters' thoughts and feelings about the laws of the universe, time, reality, and human invention are unusual and tend toward existential re-interpretation of life's meaning in relation to the technological world, then it may be classed a modernist work of literature that overlaps with the themes of science fiction. Examples include Thomas Pynchon's Gravity's Rainbow, William Burroughs's Nova Express, Kazuo Ishiguro's Never Let Me Go, and much of the work of Kurt Vonnegut, Philip K. Dick, and Stanis?aw Lem.
. Purpose of science fiction
Science fiction has often been concerned with the great hopes people place in science but also with their fears concerning the negative side of technological development; the latter is expressed in the classic theme of the hubristic scientist who is destroyed by his own creation.
