A runaway trolley, five people on the tracks, a lever, and one person on the sidetrack. This episode unpacks why a simple thought experiment breaks our brains, starting with the clash between utilitarian outcomes and deontological rules, the dirty hands problem, and the surprising origin of the dilemma in Philippa Foot’s 1967 analysis of abortion ethics and the doctrine of double effect, with the name coined by Judith Jarvis Thomson in 1976 and precursors reaching back to a 1905 questionnaire and a 1954 television play.

We explore the fat man and fat villain variations, Joshua Greene’s 2001 fMRI research showing emotional circuits hijack personal dilemmas, the role of serotonin, oxytocin and stress, the 90 percent who say they would pull the lever until a loved one is on the track, and the Vsauce simulation where five of seven participants froze. We then move into law, contrasting the 1884 cannibalism case R v Dudley and Stephens with the tort-law Hand formula from United States v. Carroll Towing, and finish with autonomous vehicles, the MIT Moral Machine’s cultural divides, and the 2016 German ethics commission that refused to let a human life be weighed in an algorithm.

• Why pulling a lever feels acceptable but pushing a man off a bridge does not
• How evolution left us unprepared to feel the horror of harm delivered by buttons and drones
• Critics Roger Scruton and Masahiro Morioka on cold arithmetic and the silenced victims
• The legal split personality: criminal law rejects the math while tort law demands it
• The buyer’s paradox of wanting utilitarian cars for everyone else and self-protecting cars for ourselves