Thought Experiments

The Same Boat

A wooden boat sits in a harbour. Every year the crew replaces a plank or two as they rot. After forty years, not a single original piece of wood is left. Meanwhile, a collector has been quietly picking the old planks out of the skip and has rebuilt them into a boat of his own, in the same shape, in a shed across town.

Which one is the original boat?

Two Boxes

A stranger with an uncanny record puts two boxes in front of you. Box A is clear and holds £1,000. Box B is sealed. Yesterday she predicted what you'd do. If she predicted you'd take only Box B, she put a million in it. If she predicted you'd take both, she left it empty. She's done this a thousand times and been right every time. The money is already in place. Nothing you do now changes it.

Do you take both boxes, or only the sealed one?

The Shadows

People have been chained in a cave since birth, facing a blank wall. Behind them a fire burns, and things pass in front of it, throwing shadows on the wall. The shadows are all anyone has ever seen, so they name them and argue about them and get good at guessing which one comes next. One prisoner gets loose, climbs out, and sees the daylight world. Then he comes back down to tell the others.

Would you believe him?

The Room of Slips

A man sits alone in a sealed room with a huge rulebook. Slips of paper covered in Chinese characters come in through a slot. He looks up each shape in the book, copies out the reply it tells him to, and pushes it back through. Outside, fluent speakers are delighted: the answers are witty and warm. The man doesn't know a word of Chinese.

Does anything in that room understand Chinese?

Mary's Grey Room

Mary has spent her whole life in a room with no colour in it. Everything is black, white or grey, including her screens and her skin. But she's the world's leading expert on colour vision. She knows every wavelength, every nerve, every last fact about what happens in a brain when it sees red. One day the door opens and she walks out into a garden of roses.

Does Mary learn something new?

The Heap

Put one grain of sand on a table. Not a heap. Add another. Still not a heap. Nobody can point to a grain where adding it turns a not-heap into a heap, yet after ten thousand grains you clearly have one. The same trick works on baldness, on being tall, on being old, on being drunk.

Where exactly does the heap begin?

The Extra Change

A cashier gives you £20 too much in change. You notice after leaving the shop. Going back will make you late, and the shop is part of a huge chain.

Do you return the money?

The Group Mark

Four of you receive the same mark for a group project. One person did almost no work. The teacher asks privately whether everyone contributed equally. Telling the truth may cause that person to fail the course.

What do you tell the teacher?

The Burning Masterpiece

A fire breaks out in a famous art gallery. The original Mona Lisa is going to burn to ash. You are standing next to a perfect 3D-printed replica. It is atom-for-atom identical to the original. You can save the replica or save a blurry photograph of the original taken by a famous artist. You only have time to grab one.

Which do you save?

The Delete Button

You are backing out of a parking spot and accidentally scrape the side of a beautiful sports car. It leaves a massive deep scratch. No one saw you do it. There are no cameras. You happen to have a prototype device that can rewind time by exactly five minutes, but you can only use it once in your entire life.

Do you use your only rewind to undo the scratch?

The Teleporter

Travel is instant now. A booth scans every atom of you, destroys the original, and rebuilds an exact copy on Mars a second later. The copy remembers breakfast, misses the same people, has your headache. Millions use it daily and none of them complain. This morning there's a fault: the scanner works, but the original you isn't destroyed. You're standing in the booth, and someone on Mars is answering to your name.

Which one of you is you?

The Pond

You're walking to work in good clothes. A small child is face down in a shallow pond, drowning. Nobody else is around. Wading in ruins your suit and shoes and makes you two hours late. Obviously you go in. Now: the same money that suit cost could, sent to the right place today, keep a child alive who you'll never meet.

What's the actual difference between the two cases?

The Payslip

By accident you see a spreadsheet with everyone's salary. A colleague who's been there longer than you, does harder work and trained you, is paid £11,000 less. She has no idea. If you tell her, she'll be furious, she may leave, and you'll have to explain how you know. If you say nothing, nothing happens.

Do you tell her?

Name the Other One

Something went wrong at work and it's traced to you. It wasn't only you; a colleague did the same thing, earlier, and nobody's noticed. Your manager offers a deal in a quiet room: give them the other name and you keep your job with a warning. Stay silent and you're out at the end of the month. Your colleague has a mortgage. So do you.

Do you say the name?

The Ring

A shepherd finds a ring that makes him invisible whenever he turns it. No cameras, no witnesses, no record. He can walk into any house, any bank, any room where people are talking about him. The story says he used it to take a kingdom.

What's the first thing you'd do with the ring, honestly?

The Novel

Your best friend has spent five years writing a novel. They quit their job and drained their savings to finish it. They finally hand you the manuscript and ask for your honest opinion. You read it over the weekend. The writing is terrible. The plot makes no sense. The book has no chance of ever getting published.

What do you say when they ask what you thought of it?

The Reference

A friend asks you to be a referee for a job she badly needs. You've worked with her. She's warm, funny, and unreliable in ways that landed on other people. The employer calls and asks the direct question: would you hire her again?

What do you say?

The Spare Room

A friend asks to stay in your spare room for two weeks after a breakup. You care about them, but they are messy and two weeks could easily become two months.

Do you let them stay?

The Better Candidate

You are hiring for a job. The strongest candidate is rude to the receptionist when they think nobody important is watching. The next candidate is less skilled but treats everyone well.

Who do you hire?

The Broken Promise

You promised to attend a close friend's birthday dinner. On the same night, you are offered a ticket to see an artist you love. The show sold out months ago, and this may be your last chance to see them.

Do you keep the promise?

The Bad Review

A small family-run restaurant serves you a terrible meal. The owner is warm, apologises, and removes it from the bill. Later, the booking site asks you to leave a public review.

What review do you leave?

The Family Discount

You own a small business. A relative asks for a large discount, saying family should help each other. Giving it would mean earning almost nothing from several days of work.

What price do you charge them?

The Private Message

A friend sends you a cruel message about someone you both know. Seconds later, they delete it and ask you to forget you saw it. The person they wrote about trusts them completely.

Do you tell the person what was said?

The Clean Slate

You have just read the greatest book you will ever read. The ending surprised you so completely that you gasped out loud. A doctor offers you a safe pill that will erase only the memory of reading this specific book. You will forget the plot, the characters, and the twist ending.

Do you take the pill so you can experience reading it for the first time again?

The Garage Sale

You are at a neighborhood garage sale. You see an old watch sitting on a folding table with a $5 sticker. You happen to know vintage watches well. This specific model is a rare Rolex worth at least $10,000. The person running the sale is an older woman clearing out her late husband's things. She seems to be struggling for money.

Do you buy the watch for $5?

The Hidden Will

Your wealthy uncle passes away. While cleaning his study, you find a hidden handwritten will dated a week before his death. In it, he leaves his entire fortune to a controversial political group you deeply despise. The current legal will leaves everything to a struggling children's hospital. You are the only person who knows this new document exists. If you burn it, the hospital gets the money.

Do you destroy the handwritten will?

The Promotion

You and your coworker are up for the same promotion. You are both equally qualified. During a casual lunch, your coworker shares a brilliant idea for a new project. Later that afternoon, the boss calls you into her office. She asks if you have any fresh ideas to help the company. Your coworker's idea would guarantee you the promotion.

Do you pitch the idea as your own?

The Dream Job

You are offered exactly what you have always wanted to do for a living. The pay is incredible. The hours are perfect. But the company makes a product you believe makes the world slightly worse. It is not illegal. It is just bad for people.

Do you sign the contract?

The Lever

A runaway train car is heading down a track towards five workers who can't hear it coming. You're standing beside a lever. Pull it and the car switches to a side track, where one worker is standing. Nobody else is around. You have about four seconds.

Do you pull the lever?

The Quiet Shortcut

Your manager asks you to skip a safety check so an urgent order can leave on time. The chance of anyone being harmed is very small. Refusing could cost the company an important client and may put jobs at risk.

Do you skip the check?

The Better Life, Plugged In

There's a machine. Lie down in it and you get the life you'd have chosen: the work going well, the person who left still there, your body behaving, your parents proud. It feels exactly like real life from the inside. You won't remember the machine. Your body is looked after. The people you leave behind are told you're fine, and in a sense you are.

Would you get in?

The Voice That Stays

After your parent dies, a company offers to build a version of them from their messages, voicemails, photos and emails. It talks like them. It remembers your childhood. It asks how you slept. It's wrong sometimes, in ways that feel exactly right. It costs a small monthly fee, and it never gets tired of you calling.

Would you subscribe?

The Promise You'd Take Back

A friend, near the end, made you promise something. Keep the letters sealed. Don't tell their kid who the father was. Sell the house to their brother. You said yes; they died easier for it. A year on you're sure the promise is doing harm to someone living. Nobody but you knows it was ever made.

Do you keep it?

The Deathbed Promise

A friend dying of cancer asks you to promise something small but strange: never tell his wife about the year he spent in debt to a man she disliked. You promise. He dies. Two years later his wife is trying to make sense of a gap in their money and their history, and she asks you straight out.

Do you keep the promise or tell her?

The Windfall

You win £80,000 in a competition you entered alone. Your sister stopped speaking to you four years ago over something she was mostly wrong about. She's now renting a damp flat with two kids and no help coming. You have savings, no dependents, and a plan for a deposit.

Do you give her some of it, and how much?

Seven Seats

A boat holds seven. There are nine of you in the water: you, someone from your family, a stranger who is a doctor, two children you don't know, and four other adults. The sea is cold and the decision has to be made in about a minute. Nobody is going to volunteer.

Who do you name to stay in the water?

Before You Knew Who You'd Be

You get to redesign the rules about money and family before you're born: how much a parent can pass to a child, what school you're entitled to, who pays for whose care in old age. You write the rules first. Then you're dropped into a random life somewhere in the country you actually live in. Could be the one you have. Could be much worse.

What rule would you write that would cost your actual family something?

The Other Life

Your partner is offered the chance they have always wanted, but it requires moving somewhere you would never choose. Going would stall your own plans. Staying would mean watching them turn down a rare chance because of you.

Would you move with them?

The Private Archive

After someone close to you dies, you gain access to their private messages. Reading them might answer questions you carried for years. It might also reveal a version of them they never chose to show you.

Would you read the messages?

The Seat at Dinner

A family member repeatedly makes cruel remarks about someone you love. Challenging them will probably split the family gathering and may end your relationship with them. Staying quiet will keep the peace, but the person beside you will notice.

What would you say at the table?

The Truth Machine

A device allows you to ask your parents one question. They are forced to answer with absolute honesty. They will not remember you asking it. You cannot share the answer with anyone else.

What question do you ask?

The Last Conversation

You get a single five-minute phone call with someone who has passed away. The connection is perfect. They know they are gone. They know you are calling from the present.

Who do you call?

The Apology

You can instantly remove the pain you caused someone in your past. All their lingering hurt from your actions will vanish. In exchange, you will experience that exact pain yourself. It will be concentrated into a single week of intense emotional suffering.

Whose pain do you take?

The Banned Guest

You are planning your wedding. It is a small intimate event. Your oldest friend has been dating a partner who is completely toxic. This partner has insulted you to your face and routinely causes public scenes. Your friend insists they will not attend your wedding unless their partner is invited.

Do you invite the partner?

The Secret Saver

A close friend comes to you in the middle of the night. They have committed a serious crime. No one was physically hurt, but their life is over if they are caught. They ask you to hide a piece of evidence. If you are caught hiding it, you will go to prison for a year.

Do you take the evidence?

Who Stays

A boat is going down. The lifeboat holds seven; there are ten of you. There's no rescue coming for days, so overloading it sinks everyone. The group looks at you to decide: an elderly doctor, a pregnant woman, a strong young man who is panicking, a child, and the rest ordinary adults, including you.

How do you decide who gets in?

Nine Months of Your Body

You wake up in a hospital wired to a stranger. Overnight, doctors connected your bloodstream to theirs. Their organs have failed; yours will keep them alive. In nine months they'll recover and walk away. Unplug now and they die. You didn't consent, nobody asked, and the person in the next bed is entirely innocent. You'd be in that bed for nine months.

Do you unplug?

The Unequal Will

A relative leaves you far more money than your sibling. There is no mistake. The will says you were more present during the relative’s final years. Your sibling believes the money should be divided equally.

How much would you give your sibling?

The Old Message

You find an old message that proves you seriously wronged someone years ago. They blamed another person and have since built a happy life. Telling the truth may ease your guilt, but it could reopen the whole affair for them.

Would you confess now?

The Empty Kidney

A relative needs a kidney. You are a match, and doctors say the risk to you is low but not zero. You love them, though you are not especially close. Nobody can force you to help, but everyone will know that you could have.

Would you donate your kidney?

The Name on the Work

You and a colleague create something valuable together. Most people assume it was mainly your work, and your career begins to benefit. Correcting the story would give them proper credit but could cost you the first real break you have had.

How publicly would you correct the story?

The Career Reset

You wake up tomorrow morning five years in the past. You have all the knowledge you possess right now. You can change your career path, your relationships and your major life decisions.

What is the very first thing you do differently?