The Trolley Problem Made a Shopping Word Famous

A trolley is a wheeled container or platform for moving things. Philosophy gave the word a second life. The *trolley problem*, set out by Philippa Foot in 1967, asks whether you should divert a runaway trolley to kill one person instead of five — a question that turned out to matter when engineers began programming self-driving cars.

• A wheeled cart (British). *A shopping trolley.*
• A streetcar (American). *A trolley car.*
• A hospital bed on wheels. *Waiting on a trolley.*
• Trolley problem — an ethical thought experiment. *The classic trolley problem.*

Word forms

How it is used in a sentence

• Return the trolley to the bay.British supermarkets.
• Patients waited on trolleys in corridors.A recurring hospital story.
• The trolley problem has no comfortable answer.Which is the point of it.

Versions of the problem

• The switch — divert the trolley, killing one instead of five
• The footbridge — push one person to stop it, which most people refuse
• The loop — a variant designed to test the reasoning
• Doctrine of double effect — the principle often invoked to distinguish the cases
• Autonomous vehicles — where the question became practical

Probably from *troll*, to roll or trundle. The American streetcar sense comes from the trolley wheel running along an overhead wire.