Among the great many novels and stories that he wrote (and is currently writing!), James Gunn’s historical and scholarly series of four volumes, “The Road to Science Fiction” clarifies and intensifies a variety of definitions and viewpoints about the development of science fiction as a genre.
Gunn’s summary strikes me as correct: “Science fiction is the branch of literature that deals with the effects of change on people in the real world as it can be projected into the past, the future, or to distant places. It often concerns itself with scientific or technological change, and it usually involves matters whose importance is greater than the individual or the community; often civilization or the (human) race itself is in danger.”
Science fiction is not normally about the present day. It is usually a kind of science-laden what-if series of ideas, fictionalized to be sure, but rooted in speculations. To be able to get at such speculations, you need a culture or cultures that have enough global reach to consider ideas outside of human experience, to consider the terms of our own futures, and to wonder about what makes things work: cultures of the sciences. For those reasons science fiction begins to take shape in the early 19th century, when globalization, scientific and technological progress reach a critical mass that radically changes cultures worldwide, and begins to beg the question of whether or not we can improve our lot through science, technology, and similar processes.
As the sciences have revealed radical new understandings (germs, ecologies, machinery, math and physics, astronomies, evolution and so much more) we can see that the old supernatural explanations and mythologies no longer explain what we know to be mostly true. (I say ‘mostly,’ because unlike absolute certainties the sciences are open to revision based on new evidence). Science fiction might be thought as a way of storytelling that deals with the products and ramifications and predictions of the new sciences in new ways for the robustness and imaginative work that is culture, a new suite of culture based on these new evidences and theories. This returns to Gunn’s core idea about a literature that deals with change, paired with the sense that people had at some point in our history to discover the idea of the future.
Writers had to discover that they could construct the settings of their stories in a future. Prior to SF most stories detail legendary tales or myths of the past, or fictions of the present, more often with magic and fantasy as their means. SF in contrast tends to be naturalizing rather than supernaturalizing, scientizing get rather than fantasizing, however fantastical it may be. It could within that context also take on other story modes: SF can be a mystery, an adventure, a romance, a tragedy, a comedy, a cowboy western, and so on. In that sense SF is really a multi genre literary series of forms, linked by emphases on projecting from the real with scientific what-if speculations.
One example of future thinking that is fiction but not science fiction is the book of revelations, looking towards an apocalyptic future borne out of prophecies coming true, book-ending the bible’s many narratives. None of these are rooted in science or technology, and as such they are best understood as future-fantasy, not science-fiction futures. But many old stories certainly set the stage for science-fiction writings, and surely many of them are apocalyptic and more recently, post-apocalyptic. Meanwhile, to look for the roots of ideas that made science fiction possible, we can cite many ancient stories, like tales of Daedalus the inventor, whose technologies sometimes went wrong.
Gunn wrote, “science and technology created social change, and the awareness of social change created science fiction.” (P.4, book 1) as such, SF is very new, since modern science is a recent innovation, the bulk of it stemming from the early 20th Century onwards. The seeds of those innovations long predate the 20th century, and so too do the narrative methods that sit at the root of science fiction. But that means SF is undeniably a contemporary art form, however much it shares precedents with many other literary forms.
Broader variations include the wider field called speculative fiction, and then within science fiction there’s many variations: cyberpunk, New Wave, slipstream, and so on. By the 1960’s, Gunn recognized that the field was so productive that no one person could read everything from any one year’s science fiction publications. That’s as true today as it was then, more so if in sf you include games, movies, television, performance/installation art about the future, and so on.