trolley problem: a standalone construct

Philippa Foot introduced the core scenario in her 1967 essay The Problem of Abortion and the Doctrine of Double Effect, asking whether the driver of a runaway tram may steer it onto a track where it will kill one person rather than stay its course and kill five. Judith Jarvis Thomson named the puzzle and gave it its standard form across two papers, Killing, Letting Die, and the Trolley Problem (1976) and The Trolley Problem (1985): a bystander who can pull a switch to divert a runaway trolley away from five people and onto one, set against variants such as pushing a heavy man from a footbridge to stop it. The construct pins the numbers plainly in favor of diverting the harm against the intuition that actively causing one death differs from merely allowing five, so it isolates the moral weight of doing versus allowing and of intending harm versus foreseeing it. Its reach makes it a landmark: the same minimal case is used in normative ethics to test consequentialist and deontological principles, in moral psychology and experimental philosophy to record how people actually judge such choices, and in recent debates over how automated systems such as self-driving vehicles should be programmed to act.[1][2][3]

Unit

A standardized moral thought experiment: one dilemma case with fixed casualty counts and a binary choice to divert the harm or not

Recovery means

Not applicable

Measured by

Presented as a scenario to participants in moral-psychology and experimental-philosophy studies, with responses recorded as judgments of whether the diverting action is permissible or required