This paper develops Lewis's (1983) analysis of truth in fiction with conventional semantics to deal with the problem of impossible fiction. Since impossible fictions depict impossible states of affairs, Lewis's framework, based on possible worlds, struggles to account for their truth conditions. Previous approaches, including quantifying over consistent fragments of fiction (Lewis, 1983) and appealing to impossible worlds (Badura & Berto, 2019), have their limitations. Instead, this paper proposes a novel solution based on conventional semantics, in which convention shifts can alter the meaning of names, predicates, and logical constants. It will be argued that conventional semantics is especially suitable to explain truths in unintended impossible fiction, but the explanation can also be extended to intended impossible fiction. The paper concludes that conventional semantics provides a compelling alternative for analysing truth in impossible fiction.
