Science Fiction
Quick answer: Science fiction extrapolates from natural law: one plausible novum, honestly followed. From Wells and Shelley to hard and soft SF, with craft advice for stories.
Science fiction is the branch of speculative fiction whose departures from reality carry a scientific alibi: the impossible thing is presented as possible, somewhere or somewhen, under natural law as we understand or plausibly extend it. In other words, fantasy asks you to believe in magic; science fiction asks you to believe in development, that time, technology or discovery could deliver the story's world from our own.
The genre spans laboratory-exact engineering tales and social thought experiments with barely a bolt in sight, and it matters to writers well beyond its shelf: SF's core discipline, extrapolation with consequences honestly paid, is a transferable craft skill, and its history is a hundred-year seminar on how ideas become stories.
The term at work: Wells rides the machine forward
H. G. Wells's The Time Machine (1895) remains the cleanest demonstration of the genre's method. The Time Traveller builds his machine, and Wells spends a single dinner-party scene giving the device a scientific alibi, time as a fourth dimension traversable as space is. Then the machine has done its work and the real subject arrives: the year 802,701, where humanity has split into the childlike Eloi above ground and the pale Morlocks below, and the Traveller slowly understands that the division is class, evolved, the leisured and the labouring made into separate species.
Notice the proportions. The technology takes a page; the consequences take the book, and the consequences aim backward at Wells's own England. Critics later gave the method a name: the novum, Darko Suvin's term for the one new thing whose implications the story works out. Mary Shelley's Frankenstein (1818) is the genre's usual ancestor on exactly these grounds, a creation with a natural alibi, galvanism, and a narrative that pays every consequence of the act.
Hard, soft and the range between
The field sorts itself, loosely, by where the rigour sits. Hard SF keeps faith with physics and engineering, and its readers check the numbers; writers like Arthur C. Clarke and Greg Egan work this end. Soft SF takes its rigour from the social sciences, anthropology, politics, psychology, and cares more about how societies bend around change; Ursula K. Le Guin is its exemplary figure. Space opera borrows SF's furniture for adventure at scale, and cyberpunk aimed the extrapolation at information, bodies and capital.
The labels are camps, not laws. What unites the genre is the honesty clause: whatever you posit, you must not quietly unposit it when the plot gets difficult. Readers of SF grant enormous initial credit and enforce the debt strictly, and most failed SF fails there, not in the science but in the bookkeeping.
How to write an SF short story
Pick one novum and keep it small enough to pay for in your wordcount: not the galactic empire but the clause in a tenancy contract after teleportation, the funeral industry after backup memory. Establish it fast and casually, trusting the reader; the door dilated is still the model, one impossible verb used as furniture. Then aim everything at a human decision the novum makes newly possible or newly costly. The oldest workshop advice in the field holds: the story should be impossible without its novum, otherwise the SF is paint.
The trap is explaining. A short story has no room for the lecture, and the lecture is always a confession of doubt; state the world as fact and the reader will build the scaffolding for you. It helps to write one private page about how the novum reached ordinary people, who profits from it, who lost work to it, what it costs on instalments, and then let none of that page into the story except as passing texture. The research shows anyway, in the confidence of the details you do use, which is the only place readers ever look for it.
Neighbours and opposites
Speculative fiction is the umbrella overhead, covering SF along with its siblings. Fantasy is the nearest sibling, distinguished by alibi: fantasy's impossibilities are frankly supernatural, SF's claim natural law, and the border cases, dying-earth tales, psionics, are shelved by tone as much as logic. Dystopia is a specialisation that turns the extrapolation political and pessimistic. Alternate history changes the past instead of the future and is usually filed under the SF roof.
The opposite, as for the whole speculative family, is realism, but SF's quarrel with realism is friendly and specific: it holds that the present is a moving train, and that fiction pretending the world stands still is the less realistic party.
What poets can take from this
- Choose one novum sized to your wordcount and pay all its consequences.
- Introduce the new thing casually, as furniture, and skip the lecture.
- Make the plot impossible without the novum, or the SF is decoration.
- Keep the honesty clause: never quietly revoke what you posited.
- Aim the extrapolation back at the present, where the story's weight lives.
Try it yourself
Write a story set the morning a technology everyone has argued about for a decade finally reaches your protagonist's small workplace, told entirely through one shift, one manager and one decision the new thing makes unavoidable. No scene may leave the building.
Questions
What is the difference between science fiction and fantasy?
The alibi. SF presents its impossibilities as natural, reachable by science, time or evolution; fantasy presents its impossibilities as supernatural and owns them as magic. A starship and a dragon can carry the same plot; the genres differ in what the reader is asked to believe about our world.
What is a novum?
Critic Darko Suvin's term for the one new thing, device, discovery or social arrangement, that distinguishes an SF story's world from ours. Strong SF typically runs on a single novum whose consequences are honestly worked out.
Does science fiction have to be set in the future?
No. Alternate histories, secret-present stories and past-set inventions all qualify. The genre's test is the naturalised departure from consensus reality, not the calendar.
By the Writory editorial team, reviewed by working poets. Updated July 2026.
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