Science fiction is, first and foremost, a fiction.  It can take multiple forms, be those prose, poetry, film, radio, digital media, the list is nearly inexhaustible.  But still, in those forms the work must be a fiction.  “Science fact,” after all, would be a physics textbook, or maybe an episode of Carl Sagan’s Cosmos.  While certainly closely related and integral to the genre of science fiction, scientific fact only informs the genre, and does not compose it.

What makes a work of fiction a work of science fiction relies on a specific distinction.  Science, of course, plays a critical part.  But we can distinguish between a thriller with scientific elements and a science fiction thriller.  This distinction is sometimes visible within the works of a single creator.  Consider Michael Crichton.  Some of his books, Sphere and The Andromeda Strain in particular, are clearly works of science fiction.  But what about a book like Congo?  Like most of his work, it is informed by scientific study.  But crucially, the science present in the book in not particularly fictive, and the inclusion of super-intelligent gorillas is more of a fantastical element.  Meanwhile, while Sphere certainly has a fantastical element to it, fictive science informs the plot, the setting, and the drama of the work.

This difference is genre defining.  The scientific aspect in a work of science fiction must be fictive.  This is why the film Gravity, while a space drama, is not science fiction, and Jurassic Park is.  The science informing the narrative has gone beyond scientific reality and shapes the work in a major way.  Science fiction, then, is a work of fiction containing in no small part fictive science.