Informationist Science Fiction theory provides a way of analysing science fiction texts and narratives in order to demonstrate on an informational basis the uniqueness of science fiction proper as a mode of fiction writing. The theoretical framework presented can be applied to all types of written texts, including non-fictional texts. In "Informationist Science Fiction Theory and Informationist Science Fiction" the author applies the theoretical framework and its specific methods and principles to various contemporary science fiction works, including works by William Gibson, Neal Stephenson and Vernor Vinge. The theoretical framework introduces a new informational theoretic re-framing of existing science fiction literary theoretic posits such as Darko Suvin's novum, the mega-text as conceived of by Damien Broderick, and the work of Samuel R Delany in investigating the subjunctive mood in SF. An informational aesthetics of SF proper is established, and the influence of analytic philosophy - especially modal logic - is investigated. The materialist foundations of the metaphysical outlook of SF proper is investigated with a view to elucidating the importance of the relationship between scientific materialism and SF. SF is presented as The Fiction of Veridical, Counterfactual and Heterogeneous Information.