Abstract Regardless of whether one agrees or disagrees with Stacie Friend’s claim that fiction is a genre, her notion of genre can be fruitfully applied to a paradigmatic genre such as science fiction. This article deploys Friend’s notion of genre in order to improve the influential characterization of science fiction proposed by Darko Suvin and to defend it from a criticism recently raised by Simon Evnine. According to Suvin, a work of science fiction must concern “a fictional ‘novum’ (novelty, innovation) validated by cognitive logic.” While Suvin conceives of his characterization as a necessary and sufficient condition for membership in the genre, I propose to cast the notions of “fictional novum” and “cognitive validation” as standard features of the genre, which works of science fiction should have but might lack. I argue that this amended version of Suvin’s characterization can better account for two basic properties of science fiction as a genre, namely its historicity and its relevance to appreciation. Lastly, I show that the amended version can shed some light on the affinity between works of science fiction and philosophical thought experiments.