How does science fiction imagine forms of life that are plausible, and yet different from anything that we already know? Fluid Futures is about how science fiction imagines an open future. Science fiction does not claim to predict what will actually happen in times to come. But it offers pictures of potential developments; it narrates the unfolding of possibilities for change that are already implicit, or incipient, in the present moment. As Rod Serling said, science fiction is “the improbable made possible.” The book starts by looking at three tools that are commonly used in science fiction to address futurity: extrapolation, speculation, and fabulation. It goes on to consider concrete examples of how science fiction texts employ these tools to illustrate ways in which the future might be different from – but not entirely discontinuous with – the present-day conditions with which we are familiar. Fluid Futures insists upon the aboutness of science fiction, as it depicts situations and ideas that are at once possible and difficult to grasp. The book then explores how the genre embraces fictionality and narrative, reconceives time, and projects images of possible worlds. The point of the book is not to give a theory of science fiction. Instead, it emphasizes the ways that science fiction texts themselves propose theories, leading readers to reconceive concepts that we have taken for granted.