Back to: Philosophy: Justice & Ethics
Philosopher Philippa Foot devised the trolley problem in 1967, and it remains the most famous thought experiment in ethics. Version one: a runaway trolley will kill five workers unless you pull a switch diverting it to a side track, where it will kill one. In surveys, around 90 percent of people say pull the switch: better one death than five.
Version two: same trolley, same five workers, but now you’re on a footbridge next to a large man, and the only way to stop the trolley is to push him off to his death. The arithmetic is identical, one life for five, yet the answers flip: only about 10 percent say pushing is permissible. Something beyond consequences is doing work in our judgments: perhaps the difference between causing harm as a side effect and using a person as a mere instrument.
The trolley problem isn’t really about trolleys (though its descendants now shape genuine debates, such as how self-driving cars should be programmed). Its purpose is diagnostic: it exposes that your moral intuitions follow principles you may never have articulated, and that those principles can conflict. The two big frameworks you’ll meet next, one focused on outcomes, one on inviolable duties, are the two voices you just heard arguing inside your own head.