An Introduction to The Trolley Problem

Would you kill one person if it meant saving five others? We dug into this classic thought experiment and asked some of our favorite Substackers for their takes.

The Trolley Problem as seen in The Good Place

Imagine this: suppose that you're standing near a set of train tracks when you spot a runaway trolley barreling toward five people. These five unfortunate souls can't hear or see the train coming, and even if they could, they can't leap out of the way in time. Then you notice a lever connected to the tracks, and you realize that if you pull it, the train will be diverted toward a second set of tracks. But disaster is inevitable, because down these tracks lies a single person in harm's way, also unable to escape in time. Would you pull the lever, leading to one death, but saving five lives? Or is it inherently wrong to take an action causing the death of one innocent person, even if five others are spared?

You've just experienced the Trolley Problem, a thought experiment first posed in 1967 by British philosopher Philippa Foot. The Trolley Problem has since cast a long shadow as a staple of moral philosophy, ethics education, and even real life moral dilemmas.

But this isn't just a thought experiment. In 1884, Captain Thomas Dudley and his crew aboard the shipwrecked yacht Mignonette faced this exact moral calculus in real life. After three weeks lost at sea, they made an impossible choice: kill and eat their cabin boy Richard Parker, or let all four men starve to death. Their decision to kill Richard Parker sparked a landmark murder trial that forever changed how law and ethics intersect—the true story at the heart of Adam Cohen's book, Captain's Dinner. Was it acceptable to kill Parker if his death allowed others to survive, or is murder always unacceptable, no matter the circumstances? That's the ethical quandary for which the crew of the Mignonette stood trial—and the question still animating conversations about the case even today.

Nowadays, fewer sailors are fending for survival in lifeboats, but contemporary applications of the Trolley Problem are everywhere, from medicine to self-driving cars to even pop culture. To dig into this lively topic, we invited some of Substack's finest thinkers on philosophy, ethics, and history to share their favorite Trolley Problem-related material. Read on for examples from real life history, philosophical essays, and even a must-watch episode of television.

The Nez Perce: A Native American Trolley Problem

Only seven years before the Mignonette trial in England, a moral dilemma echoing the trolley problem was playing out on the American frontier. In 1877, the Nez Perce, a typically peaceful Native American nation renowned to this day for their Appaloosa horses, were relentlessly pursued by the military while fleeing U.S. government-forced relocation. Tribal families carried their small children, the elderly, the sick, and the wounded over one thousand miles of treacherous terrain. When they were less than forty miles from the safety of the Canadian border, their progress was halted under the weight of the dying. White Bird, their shaman, broke with his chief and led a band of followers into Canada. Chief Joseph, unwilling to abandon the remaining tribe, surrendered when his people simply could not go farther. This story has always stayed with me because it is both tragic and poignant: survival weighed against loyalty. It is a choice no one should ever confront, yet displaced people in our own time continue to suffer the same life-or-death hardships and urgent moral dilemmas.

-Julia Henri, Juicy History

The Doctrine of Double Effect

I would go with the philosophical angle when approaching this dilemma, and that would be the Doctrine of Double Effect. Say you can take an action that will save five lives, but end one life—then it’s okay, so long as you did not maliciously intend to cause the end of that life. So taking that one life to save five is good, because it happened as a side effect of a well-intended action to save those five lives. However, applying this idea to do the greater good is of course a better outcome than if you took a well-intended action and just traded one life for another. That’s a much more gray area.

-S.E. Bagwell, History Odds and Ends

Two Essays Worth Reading

Most discussion of the Trolley Problem adopts the perspective of the agent in the situation: what would (or should) you do? My main recommendation for readers is to take a broader view of the problem, and start by asking: what should we, as impartial bystanders, want the agent to do?

It can be especially interesting to consider a variation in which killing one would prevent five other killings (not just five accidental deaths). Shouldn't bystanders want the number of killings to be minimized? And if so, would it be objectionably self-indulgent for a moral agent to prioritize their own clean hands over what a benevolent ideal observer would want them to do?

A couple of background readings for anyone interested in pondering these questions in more depth:

1. Samuel Scheffler's (1985) 'Agent-Centered Restrictions, Rationality, and the Virtues' offers a classic exploration of the "paradox of deontology", asking: "How can the minimization of morally objectionable conduct be morally unacceptable?"

2. My (2025) 'Preference and Prevention: A New Paradox of Deontology' develops the challenge further by especially focusing on the question of what bystanders should prefer, and what implications this has for what the agent ought to do.

-Richard Yetter Chappell, Good Thoughts

Two Connected Greek Myths

Considering I focus on the ancient world, I think there are actually two (connected) Greek myths that exemplify the trolley problem and highlight how sometimes every possible choice leads to tragedy. In the first myth, Agamemnon, the leader of the Greek army before the Trojan War, is told by the goddess Artemis that the only way to gain favorable winds for his ships is to sacrifice his own daughter, Iphigenia. He must decide whether to kill her to save his army and ensure the war can begin, or spare her life and doom the expedition. He chooses the former. Similarly, in the story of Orestes, after his father Agamemnon is murdered by his mother, Clytemnestra (most likely for killing their daughter Iphigenia), Orestes faces the impossible choice of either avenging his father by committing matricide or sparing her and betraying the duty of vengeance owed to his father. He is pursued by the Furies after killing his mother and is only relieved by a heavenly pardon. I think these myths show that moral dilemmas aren’t about finding a perfect solution, but about carrying the heavy responsibility of choosing when every path causes harm.

-Anya Leonard, Classical Wisdom

The Good Place, Season Two, Episode Six: The Trolley Problem

While I was writing this book, I told my 9-year-old niece what it was about, and how Captain Dudley decided to kill the cabin boy to save the lives of himself and two other people in the boat. She looked at me with an air of exasperation and said, "It's just like the Trolley Problem." Of course, I knew the facts of the story were a lot like the Trolley Problem, but I could not for the life of me figure out how she did -- since even many of my adult friends had never heard of the Trolley Problem, and I don't recall it being part of my own 4th grade curriculum. I later found out that she had learned about it from watching an episode of "The Good Place," the philosophy-minded sit-com. (Even so, I am still amazed that at her age she was able to see that the situation in the lifeboat was analogous to the predicament of the Trolley conductor.)

All of this led me to watch "The Good Place" episode on the Trolley Problem (Season 2, episode 6.) It's actually quite well done, and impressively high-low. There is a fair amount of wacky re-enactments of Trolley Problem scenarios, complete with gobs of fake blood. But the show is also erudite enough to namecheck Philippa Foot, the English philosopher who first thought of it. (Which got me thinking of the uncanny coincidence that Captain Dudley's wife was also named Phillipa. But I digress . . .) Hardly your average sitcom fare. Anyway, my verdict is that the "Trolley Problem" episode is definitely worth a watch.

-Adam Cohen, author of Captain’s Dinner

A Second Vote for The Good Place

I think the trolley problem is a helpful exercise to remind us that moral questions are more complex than we might think - that it's usually not possible to base our moral reasoning on a single principle. I also think that we can overstate its helpfulness in practice, since when we're actually making moral decisions it's often in the moment. So for a recommendation, I might actually point to the Trolley Problem episode of The Good Place (season 2 episode 6), because it illustrates hilariously how even if we've thought a lot about the issue, in the moment we might simply freeze up. I've written about the overall use of the trolley problem here, and the Good Place episode here.

-Amod Sandhya Lele, Lover of All Wisdom

Trial by Trolley

The Trolley Problem is serious business, but Trial by Trolley is anything but. This card game from the twisted minds behind Cards Against Humanity and Joking Hazard designates one player as the trolley operator; other players split into two teams, draw cards to design each track, then petition the conductor to spare their lives by murdering their opponents. Each track contains “innocent” would-be victims (think “the last honey bees”) and “guilty” would-be victims (think “the world’s most obnoxious fraternity”), making the conductor’s decision all the more ethically fraught. If you, like me, think that game night isn’t game night without some good old-fashioned arguing, then Trial by Trolley is a must-have.

-Adrienne Westenfeld, writer and editor