There have been many attempts at defining science fiction.[1] This is a list of definitions that have been offered by authors, editors, critics and fans over the years since science fiction became a genre. Definitions of related terms such as "science fantasy", "speculative fiction", and "fabulation" are included where they are intended as definitions of aspects of science fiction or because they illuminate related definitions—see e.g. Robert Scholes's definitions of "fabulation" and "structural fabulation" below. Some definitions of sub-types of science fiction are included, too; for example see David Ketterer's definition of "philosophically-oriented science fiction". In addition, some definitions are included that define, for example, a science fiction story, rather than science fiction itself, since these also illuminate an underlying definition of science fiction.

The Encyclopedia of Science Fiction, edited by John Clute and Peter Nicholls, contains an extensive discussion of the problem of definition, under the heading "Definitions of SF". The authors regard Darko Suvin's definition as having been most useful in catalysing academic debate, though they consider disagreements to be inevitable as science fiction is not homogeneous. Suvin's cited definition, dating from 1972, is: "a literary genre whose necessary and sufficient conditions are the presence and interaction of estrangement and cognition, and whose main formal device is an imaginative framework alternative to the author's empirical environment".[2] The authors of the Encyclopedia article—Brian Stableford, Clute, and Nicholls—explain that, by "cognition", Suvin refers to the seeking of rational understanding, while his concept of estrangement is similar to the idea of alienation developed by Bertolt Brecht, that is, a means of making the subject matter recognizable while also seeming unfamiliar.

Tom Shippey compared George Orwell's Coming Up for Air (1939) with Frederik Pohl and C. M. Kornbluth's The Space Merchants (1952), and concluded that the basic building block and distinguishing feature of a science fiction novel is the presence of the novum,[3] a term Darko Suvin adapted from Ernst Bloch and defined as "a discrete piece of information recognizable as not-true, but also as not-unlike-true, not-flatly- (and in the current state of knowledge) impossible."[4]

The order of the quotations is chronological; quotations without definite dates are listed last.


In chronological order

  1. All stories set in the future, because the future can't be known. This includes all stories speculating about future technologies, which is, for some people, the only thing that science fiction is good for. Ironically, many stories written in the 1940s and 1950s that were set in what was then the future—the 1960s, 1970s and 1980s—are no longer "futuristic." Yet they aren't "false," either, because few science fiction writers pretend to be writing what will happen. Rather, they write what might happen. So those out-of-date futures, like that depicted in the novel 1984, simply shift from the "future" category to:
  2. All stories set in the historical past that contradict known facts of history. Within the field of science fiction, these are called "alternate world" stories. For instance, what if the Cuban Missile Crisis had led to nuclear war? What if Hitler had died in 1939? In the real world, of course, these events did not happen—so stories that take place in such false pasts are the purview of science fiction and fantasy.
  3. All stories set in other worlds, because we've never gone there. Whether "future humans" take part in the story or not, if it isn't Earth, it belongs to this genre.[46]
  4. All stories supposedly set on Earth, but before recorded history and contradicting the known archaeological record—stories about visits from ancient aliens, or ancient civilizations that left no trace, or "lost kingdoms" surviving into modern times.
  5. All stories that contradict some known or supposed law of nature. Obviously, fantasy that uses magic falls into this category, but so does much science fiction: time travel stories, for instance, or "invisible man" stories.

Undated (alphabetically by author)


  1. ^ From the introduction to George O. Smith's Venus Equilateral series, originally published in 1947.[11]
  2. ^ Originally published in the May 1966 issue of Extrapolation.[21][22]


  1. ^ For example, Patrick Parrinder comments that "[d]efinitions of science fiction are not so much a series of logical approximations to an elusive ideal, as a small, parasitic subgenre in themselves." Parrinder, Patrick (1980). Science Fiction: Its Criticism and Teaching. London: New Accents.
  2. ^ Stableford, Brian; Clute, John; Nicholls, Peter (1993). "Definitions of SF". In Clute, John; Nicholls, Peter (eds.). Encyclopedia of Science Fiction. London: Orbit/Little, Brown and Company. pp. 311–314. ISBN 1-85723-124-4.
  3. ^ Shippey, Tom (1991) Fictional Space. Essays on Contemporary Science Fiction, page 2, Humanities Press International, Inc., NJ
  4. ^ Suvin, Darko (1979) Metamorphoses of Science Fiction: On the Poetics and History of a Literary Genre, New Haven, pp. 63–84.
  5. ^ Originally published in the April 1926 issue of Amazing Stories
  6. ^ a b c d e f g h i Quoted in [1993] in: Stableford, Brian; Clute, John; Nicholls, Peter (1993). "Definitions of SF". In Clute, John; Nicholls, Peter (eds.). Encyclopedia of Science Fiction. London: Orbit/Little, Brown and Company. pp. 311–314. ISBN 1-85723-124-4.
  7. ^ Originally published in Pilgrims of Space and Time (1947)
  8. ^ a b c d Quoted in Jakubowski, Maxim; Edwards, Malcolm, eds. (1983) [1983]. The Complete Book of Science Fiction and Fantasy Lists. London: Granada. ISBN 0-586-05678-5.
  9. ^ a b Originally in Eshbach, Lloyd Arthur, ed. (1947). Of Worlds Beyond. New York: Fantasy Press. p. 91.; cited from 1964 reprint.
  10. ^ Budrys, Algis (October 1967). "Galaxy Bookshelf". Galaxy Science Fiction. pp. 188–194.
  11. ^ Smith, George O. (1975). Venus Equilateral. London: Futura Publications. pp. 9–10.
  12. ^ Knight, Damon (1952). "Science Fiction Adventures". Science Fiction Adventures (1952 magazine) (1): 122. Punctuation was misprinted in the original magazine; the quote is punctuated as Knight had it in his collection of essays In Search of Wonder, Chicago: Advent, 1956.
  13. ^ James Blish, writing as William Atheling, Jr., cited this definition of Sturgeon's from a talk he had given. Blish's article was published in the Autumn 1952 issue of Red Boggs' fanzine Skyhook. Sturgeon subsequently complained to Blish that he had intended the definition to apply only to good science fiction.Atheling Jr., William (1967). The Issue At Hand. Chicago: Advent. p. 14.
  14. ^ Davenport, Basil (1955). Inquiry Into Science Fiction. New York: Longmans, Green and Co. p. 15.
  15. ^ Wyndham, John (1963). The Seeds of Time. Harmondsworth: Penguin. p. 7., quoted from the Penguin reprint; the original publication was 1956 by Michael Joseph.
  16. ^ "Definitions of Science Fiction". Archived from the original on 18 October 2006. Retrieved 3 December 2006.
  17. ^ From Heinlein's essay "Science Fiction: Its Nature, Faults and Virtues", originally in Davenport, Basil, ed. (1959). The Science Fiction Novel: Imagination and Social Criticism. Advent.; cited from Knight, Damon, ed. (1977). Turning Points:Essays on the Art of Science Fiction. New York: Harper and Row. p. 9. ISBN 9780060124328.
  18. ^ Amis, Kingsley (1960). New Maps of Hell. New York: Ballantine. p. 14.
  19. ^ Atheling, William Jr. Science-Fantasy and Translations: Two More Cans of Worms in Atheling, William Jr (1970). Blish, James (ed.). More issues at hand; critical studies in contemporary science fiction. Chicago: Advent. p. 100. ISBN 978-0-911682-10-6. According to the front matter, this essay was originally published in two parts, in 1960 and 1964. Blish, writing as William Atheling, Jr., lists a variety of sources, some fanzines and some professional magazines, from which the book was drawn, but does not specify which particular sources formed the basis of this essay.
  20. ^ Rod Serling (1962-03-09). The Twilight Zone, "The Fugitive".
  21. ^ Parrinder, Patrick (2000). Learning from Other Worlds. Liverpool: Liverpool University Press. p. 300.
  22. ^ Clareson, Thomas D. (1971). Sf: The Other Side of Realism. Bowling Green, OH: Bowling Green University Popular Press. p. 60.
  23. ^ Quoted by Algis Budrys in a review of Best SF: 1967. Budrys, Algis (November 1968). "Galaxy Bookshelf". Galaxy Science Fiction. pp. 160–166.
  24. ^ Budrys, Algis (September 1968). "Galaxy Bookshelf". Galaxy Science Fiction. pp. 187–193.
  25. ^ Pohl, Frederik (December 1968). "The Great Inventions". Editorial. Galaxy Science Fiction. pp. 4–6.
  26. ^ Originally published in 1972
  27. ^ Aldiss, Brian (1973). Billion Year Spree. Garden City, N.Y., Doubleday. ISBN 9780385088879.
  28. ^ Aldiss, Brian; Wingrove, David (1986). Trillion Year Spree: The History of Science Fiction. London: Gollancz. ISBN 0-575-03942-6.
  29. ^ Farrell, Edmund J.; Gage, Thomas E.; Pfordresher, John; et al., eds. (1974). Science Fact/Fiction. Scott, Foresman and Company. Introduction by Ray Bradbury.
  30. ^ The quote is from the introduction to Spinrad, Norman, ed. (1974). Modern Science Fiction. Anchor Press. ISBN 9780385022637.
  31. ^ Asimov, "How Easy to See the Future!", Natural History, 1975
  32. ^ a b Scholes, Robert (1975). Structural Fabulation. ISBN 9780268005702.
  33. ^ Scholes, Robert; Rabkin, Eric S. (1977). Science Fiction: History, Science, Vision. London: Oxford University Press. ISBN 978-0-19-502174-5.
  34. ^ Road to Science Fiction Vol 1.
  35. ^ Metamorphoses of SF No 63.
  36. ^ a b Parrinder, Patrick (1980). Science Fiction: Its Criticism and Teaching. London: New Accents. p. 15.
  37. ^ Dick, Philip K. (1995). The shifting realities of Philip K. Dick : selected literary and philosophical writings. Edited and with an introduction by Lawrence Sutin (1st Vintage Books ed.). New York: Vintage Books. ISBN 0679747877. OCLC 35274535.
  38. ^ Malzberg, Barry N. (1982). "The Number of the Beast". The Engines of the Night : Science Fiction in the Eighties. Doubleday. In an preview of this book, Malzberg wrote "past" rather than "future": Malzberg, Barry N. (August 1981). "The Engines of the Night: The Number of the Beast" (PDF). Science Fiction Review (40): 19–22.
  39. ^ Pringle, David (1985). Science Fiction: The 100 Best Novels. London: Xanadu. p. 9.
  40. ^ Robinson, Kim Stanley (1987). "Toward a Definition of "Science Fiction"". Foundation: the international review of science fiction (40). ISSN 0306-4964. Archived from the original on December 1, 2014. Retrieved 2014-12-01.
  41. ^ Evans, Christopher (1988). Writing Science Fiction. London: A & C Black. p. 9.
  42. ^ Greenberg, Martin; Asimov, Isaac, eds. (1990). Cosmic Critiques. Cincinnati: Writer's Digest Books. p. 6.
  43. ^ Clarke, Arthur C. (2000). Patrick Nielsen Hayden (ed.). The Collected Stories of Arthur C. Clarke. New York: Orb Books. p. ix. ISBN 0-312-87860-5.
  44. ^ Prucher, Jeff (2007). Brave New Words. Oxford: Oxford University Press. p. 171.
  45. ^ Card, Orson Scott (September 28, 2010). "Defining Science Fiction and Fantasy". Writer's Digest. Retrieved December 21, 2023.
  46. ^ Humans have visited the Moon.
  47. ^ Milner, Andrew (2012). Locating Science Fiction. Liverpool: Liverpool University Press. pp. 39–40.
  48. ^ Pandey, Ashish (2005). Academic Dictionary of Fiction. Delhi, India: Isha Books. p. 137. ISBN 9788182052628. Retrieved 3 October 2011.
  49. ^ Malzberg, Barry N. (August 1981). "The Engines of the Night: The Number of the Beast" (PDF). Science Fiction Review (40): 19–22.