These definitions of science fiction are for those of you who are not satisfied with Damon Knight's definition of science fiction: "...[Science Fiction] means what we point to when we say it."
Brian W. Aldiss
Science fiction is the search for definition of man and his status in the universe which will stand in our advanced but confused state of knowledge (science), and is characteristically cast in the Gothic or post-Gothic mould.
-- Trillion Year Spree: the History of Science Fiction (London, 1986)
Is it any wonder that a new generation has rediscovered science fiction, rediscovered a form of literature that argues through its intuitive force that the individual can shape and change and influence and triumph; that man can eliminate both war and poverty; that miracles are possible; that love, if given a chance, can become the main driving force of human relationships?
Science Fiction is that class of prose narrative treating of a situation that could not arise in the world we know, but which is hypothesized on the basis of some innovation in science or technology, or pseudo-technology, whether human or extra-terresial in origin.
-- New Maps Of Hell (London, 1960)
Science fiction reflects scientific thought; a fiction of things-to-come based on things-on-hand.
-- The Fantastic Mirror-SF Across The Ages (Panthenon 1969)
Modern science fiction is the only form of literature that consistently considers the nature of the changes that face us, the possible consequences, and the possible solutions.
That branch of literature which is concerned with the impact of scientific advance upon human beings.
James O. Bailey
The touchstone for scientific fiction, then, is that it describes an imaginary invention or discovery in the natural sciences. The most serious pieces of this fiction arise from speculation about what may happen if science makes an extraordinary discovery. The romance is an attempt to anticipate this discovery and its impact upon society, and to foresee how mankind may adjust to the new condition.
-- Pilgrims Through Space and Time (New York, 1947)
SF is a controlled way to think and dream about the future. An integration of the mood and attitude of science (the objective universe) with the fears and hopes that spring from the unconscious. Anything that turns you and your social context, the social you, inside out. Nightmares and visions, always outlined by the barely possible.
Science fiction is really sociological studies of the future, things that the writer believes are going to happen by putting two and two together.
Science fiction is story-telling, usually imaginative as distinct from realistic fiction, which poses the effects of current or extrapolated scientific discoveries, or a single discovery, on the behavior of individuals of society.
Mainstream fiction gives imaginative reality to probable events within a framework of the historical past or present; science fiction gives reality to possible events, usually in the future, extrapolated from present scientific knowledge or existing cultural and social trends. Both genres ordinarily observe the unities and adhere to a cause-and-effect schema.
Science Fiction: fiction based on rational speculation regarding the human experience of science and its resultant technologies.
[Science Fiction is:]a subdivision of fantastic literature which employs science or rationalism to create an appearance of plausibility.
-- Posted to the mailing list SF-LIT, May 16, 1996
As its best, SF is the medium in which our miserable certainty that tomorrow will be different from today in ways we cant predict, can be transmuted to a sense of excitement and anticipation, occasionally evolving into awe. Poised between intransigent scepticism and uncritical credulity, it is par excellence the literature of the open mind.
John W. Campbell, Jr.
The major distinction between fantasy and science fiction is, simply, that science fiction uses one, or a very, very few new postulates, and develops the rigidly consistent logical consequences of these limited postulates. Fantasy makes its rules as it goes along...The basic nature of fantasy is "The only rule is, make up a new rule any time you need one!" The basic rule of science fiction is "Set up a basic proposition--then develop its consistent, logical consequences."
-- Introduction, Analog 6, Garden City, New York, 1966