Trolley problem
The trolley problem is a thought experiment in moral philosophy and moral psychology with many variations, involving hypothetical ethical dilemmas about whether to sacrifice one person to save a larger number of people. The series usually begins with a scenario in which a runaway trolley (tram) or train is on course to collide with and kill a number of people (traditionally five) tied to the tracks, but a driver or bystander can intervene and divert the vehicle to kill just one person on a different track.