Justin Fritz Leiber (/ˈlaɪbər/ LY-bər;[1] July 8, 1938 – March 22, 2016) was an American philosopher and science fiction writer.

[6][9] Leiber's publications encompass a number of subjects, including philosophy, psychology, linguistics, and cognitive science.

Provocative and detailed, the description has been anthologized in several text books, most notably in Douglas Hofstadter and Daniel Dennett's The Mind's I.

In Beyond Humanity, the protagonist deals with the claims to personhood of both apes and computers – themes that Hackett Publishing suggested might also be incorporated into a dialogue, Can Animals and Machines Be Persons?

In Beyond Gravity, Leiber's protagonist discovers that earth has long been studied by alien “anthropologists,” who write articles about humans which appear in a journal whose title might be translated into humanese as “Primitivity Review.” As this description suggests, Leiber's Beyond trilogy is largely taken up with issues in philosophy and cognitive science.