25 Speculative “What If” Writing Prompts

Every genre of speculative fiction — science fiction, alternate history, magical realism, dystopia — reduces, at the level of premise, to a single move: take one true thing about the world and make it false, or take one false thing and make it true. Everything else stays the same. Gravity still pulls down. People still fall in love badly, grieve unevenly, lie to protect themselves. The only variable the writer controls is the premise, and the only real work is following that premise honestly to its human consequences.

This is harder than it sounds, because the instinct of most beginning speculative writers is to treat the "what if" as the destination rather than the starting gate. A story that stops at "what if memories could be sold" hasn't written anything yet — it's described a setting. The story begins when a specific person, with a specific need, has to decide what to do inside that changed world. The premise is not the plot. The premise is the pressure the plot has to survive.

"Science fiction writers foresee the inevitable, and although problems and catastrophes may be inevitable, solutions are not."

— Isaac Asimov

The twenty-five prompts below are organized by the kind of change at their center: technological, biological, political, social, and the more intimate category of altered personal history. Each prompt names the single changed premise and leaves the human consequence for you to discover. Use them as story seeds, flash fiction exercises, or the opening scene of something longer — the "what if" only needs to survive the first page; after that, it's a story about a person.

Technological Change

These prompts start with a single invention or capability, then ask what it does to the texture of ordinary life — not the headline, but the Tuesday afternoon six years after the headline.

1. 01 What if you could pay to have a single memory permanently removed, with no side effects and no record of what was taken? Write a character who is trying to figure out, from the shape of the absence, what her sister paid to forget.
2. 02 What if every device with a screen displayed, in the corner, a running number of days left in the average life expectancy of whoever was looking at it — updated in real time based on their own health data? Write the first time a character's number drops.
3. 03 What if translation implants made every language mutually intelligible, instantly, everywhere — and a linguist discovers that one small, dying language refuses to translate correctly, always rendering as something slightly wrong? Write her first real conversation with a speaker of it.
4. 04 What if it became possible to record and replay a single day of your life exactly as you experienced it, sensation for sensation, but only once? Write the day a character finally decides which day to spend it on.
5. 05 What if an algorithm could predict, with 94% accuracy, which marriages would end in divorce within five years — and courts began requiring the score before issuing a marriage license? Write a couple's appointment to receive their number.

Biological Change

These prompts alter something about bodies, aging, or the mechanics of life itself, then follow the change into family, intimacy, and the practical business of being a person with a body.

6. 06 What if humans stopped aging biologically at twenty-five, but only for those born after a certain year — meaning some families now have parents who look younger than their adult children? Write a scene at a holiday dinner.
7. 07 What if grief had a measurable biological endpoint — a day, roughly the same for everyone, after which the body simply stops producing the chemical signature of mourning? Write a character who is still grieving three days after that date, and what she starts to suspect about herself.
8. 08 What if a newly discovered organ, present in everyone but only recently identified, turned out to store something like moral instinct — and could be scanned to reveal how a person would behave under specific pressures? Write the scene where a character gets her results back.
9. 09 What if identical twins could, for one hour a year, fully swap sensory experience — feeling exactly what the other feels, everywhere they are? Write the year one twin uses the hour to say goodbye.
10. 10 What if a virus swept the world that didn't kill or sicken anyone, but permanently erased the survivors' capacity to feel fear — and a decade later, a generation of fearless children is coming of age? Write a parent trying to teach caution to a child who cannot physically experience it.

Political & Social Structure

These prompts change a law, an institution, or the rules a society runs on, then follow one person navigating the new structure from the inside — not as a thesis statement, but as a life.

11. 11 What if voting rights were tied not to citizenship or age but to a demonstrated understanding of the specific policy being voted on, verified through a short interview? Write the story of an election-day interviewer and the voter she has to fail.
12. 12 What if every citizen were required, once in their life, to spend one full year living at the median income and housing conditions of their country — no exceptions, including for the wealthy and powerful? Write the diary of someone's assigned year.
13. 13 What if inheritance above a certain amount were abolished entirely, redistributed at death to a lottery of citizens instead of to family — and a woman wins the fortune of a stranger whose children are furious? Write their first meeting.
14. 14 What if a country adopted a law requiring every new parent to complete a one-year apprenticeship under an experienced parent before regaining custody of their newborn? Write the apprenticeship from the perspective of the mentor, who has reasons of her own for taking the assignment.
15. 15 What if a city built its public transit system to be free, silent, and mandatory-priority for anyone visibly in emotional distress, with trained staff on every car — and a man who has been faking a crisis for the free ride finally meets a staff member who sees through him, and helps anyway? Write the ride.

Everyday Rules of Reality

These prompts change one small, universal rule of physical or social reality — not the whole world, just one law of how things work — and ask what a life looks like inside the new rule.

16. 16 What if lying were physically impossible — not detected, but structurally unspeakable, the way it's impossible to say a sentence backward at speed — and everyone had grown up inside total honesty as the only available condition? Write the first time a character encounters someone from a culture where lying is still possible.
17. 17 What if names had to be renegotiated with the people who gave them to you every five years, by mutual consent, or they stopped working — people simply couldn't hear them anymore? Write a daughter's fifth renegotiation with her estranged father.
18. 18 What if debts of gratitude were literally binding — if helping someone in genuine need created an enforceable obligation they had to repay, tracked and collectible like a loan? Write a character who realizes she is owed, and owing, more than she can ever settle.
19. 19 What if every building retained a faint, permanent physical trace of the strongest emotion ever felt inside it, perceptible to anyone who paid attention? Write a real estate agent showing a house she knows the history of, to a buyer who can feel it but doesn't know why.
20. 20 What if the dead could be reached, once, for exactly one unscripted conversation of unknown length — no warning when it would end, no way to schedule it in advance? Write the conversation a character has been rehearsing for years, interrupted at the wrong moment.

Altered Personal History

The most intimate register of speculative fiction changes not the world but one person's past — a single fact of their own history rewritten, and the self that has to be rebuilt around the new fact.

21. 21 What if a woman discovered, at forty, definitive proof that a childhood memory she has built her entire personality around — a act of courage, a moment of being chosen — never actually happened the way she remembers it? Write the week after she finds the proof.
22. 22 What if a man learned that a decision he has always described as his defining moment of free will was, in fact, engineered by his family without his knowledge, years in advance? Write the conversation where he finds out, and who he blames.
23. 23 What if you woke up one morning with all your memories intact except for a single relationship, entirely and specifically erased — you know the person existed, you have photos, but you feel nothing when you see their face? Write the reunion.
24. 24 What if a person discovered they had lived an entirely different life for a period of years they cannot account for — a life with a different name, different choices, evidence of a self they don't recognize and can't disown? Write their first attempt to meet someone who knew that version of them.
25. 25 What if the single worst thing you ever did could be permanently, invisibly undone — erased from every record and every memory but your own — but only if you told someone the full truth of it first, out loud, to their face? Write the confession.

Following the Premise Past the Premise

The failure mode of "what if" fiction is stopping at wonder. A premise that is merely clever — however inventive the mechanism — reads as a thought experiment rather than a story, because thought experiments don't need characters to want anything. The move that turns premise into fiction is asking a second question immediately after the first: given this changed rule of the world, what does this specific person, with this specific history, now have to decide? The premise creates the pressure. The character's want, under that pressure, creates the plot.

It's worth noticing, too, that the strongest speculative premises are usually narrow rather than sweeping. "What if everyone could read minds" is harder to write well than "what if one specific stranger on your commute could read yours" — because the narrower premise still has edges, still has a world outside it that behaves normally, and normalcy is what makes the one changed thing feel dangerous rather than merely strange. When in doubt, change less. Follow it further.