Guide
The trolley problem, and the modern versions people vote on
A runaway trolley is heading towards five people tied to the track. You are standing next to a lever. If you pull it, the trolley switches to a side track where it will kill one person instead. Do you pull it?
That is the whole problem, and people have been arguing about it for more than fifty years.
Where it comes from
The philosopher Philippa Foot described the scenario in 1967, in a paper about the ethics of harm. Judith Jarvis Thomson gave it the name "trolley problem" in 1976 and later added the variation that made it famous.
Why it is so hard
If only the numbers matter, the answer is easy: one death is better than five. That is the utilitarian view. But most people feel there is a difference between letting something happen and doing it yourself, and that some things you should not do to a person even to save others. That is the deontological view.
The trolley problem is hard because most of us hold both views at once, and this scenario is built to make them disagree.
The best-known variations
Changing small details changes what people answer, which is what makes the problem useful.
- The footbridge: instead of a lever, you can stop the trolley by pushing a large stranger off a bridge onto the track. Same numbers, one for five, yet far fewer people say they would do it.
- The loop: the side track loops back, and the one person's body is what stops the trolley. You are now using them as a means, not just redirecting harm.
- The surgeon: five patients need organs and one healthy visitor could supply them all. Almost nobody accepts this one, even though the arithmetic is identical.
The trolley problem in real life
It stopped being purely theoretical with self-driving cars, which may one day have to choose between harms. MIT's Moral Machine experiment collected about 40 million decisions from people in 233 countries and territories, and found clear cultural differences in who people chose to spare.
The dilemmas below are smaller and more personal: one parachute, one seat on the lifeboat, one person you can save. They ask the same question in a way that feels less like a thought experiment.
Modern trolley problems, with the real vote
A few sacrifice and "who do you save" dilemmas from the archive, with the current split. Decide before you read the percentages.
Sacrifice
You lead a rescue team after an earthquake. Your brother is trapped in an unstable sector. Sending your team to get him risks their lives in an imminent collapse.
51% Order retreatSend the team 49%213 votes
Sacrifice
You are a mountain guide caught in a blizzard. Your younger brother is injured and cannot walk. If you stay to carry him, the group of four hikers you are guiding will get lost and die. If you lead the group down, your brother will freeze to death.
47% Lead the groupStay with him 53%583 votes
Sacrifice
You work to the limit to keep your home. Your 17-year-old child studies constantly for a scholarship to escape poverty. If they don't help with your job now, you will lose the house and fall severely ill. If they help, they lose the scholarship.
47% I push through aloneI ask for help 53%190 votes
Sacrifice
A broken valve is leaking toxic gas at your factory. If you go in to close it, you will suffer permanent lung damage. If you don't, your colleague, a young father, will have to do it.
45% I go inLet him go 55%594 votes
Questions
- What do most people answer?
- In the classic lever version, most people in surveys say they would pull it. In the footbridge version, where you have to push someone, the majority flips and most say they would not.
- Is there a correct answer to the trolley problem?
- No. It is a tool for exposing which principle you rely on, not a puzzle with a solution. Philosophers still disagree.
- Is doing nothing also a choice?
- That is the point of the lever. Standing still means five people die, so refusing to choose is itself a choice, and many people feel responsible either way.