The Trolley Problem: A Classic Ethical Thought Experiment
You’re standing beside a railway track. A runaway trolley is heading straight toward five people who are tied to the track and cannot move. You can pull a lever that would divert the trolley onto another track—where only one person is tied up.
Do you pull the lever?
Welcome to The Trolley Problem, one of moral philosophy’s most famous and unsettling dilemmas. First introduced by philosopher Philippa Foot in 1967 and later expanded by Judith Jarvis Thomson, this thought experiment forces us to question the foundations of morality—specifically, whether it’s more ethical to act or refrain from acting when both choices involve harm.
There’s no perfect answer, but how we think about this problem reveals a lot about how we define right and wrong.
The Basic Dilemma
Let’s break it down:
Option A: Do nothing. The trolley continues on its path, killing five people.
Option B: Pull the lever. The trolley switches tracks and kills one person.
If you pull the lever, you actively cause a death—but you save five lives. If you do nothing, you let five people die, but you haven’t “caused” any harm directly.
This setup pits utilitarianism (minimize total harm) against deontological ethics (don’t do harm, regardless of outcome).
The Utilitarian View
Utilitarians argue that we should always do the thing that maximizes well-being—or minimizes harm.
From this perspective, pulling the lever is morally right. One death is better than five. Simple math.
This logic often drives decisions in public health, emergency management, and even self-driving car programming. Sacrificing one life to save five makes statistical sense.
But… are people statistics?
The Deontological View
Deontologists, following thinkers like Immanuel Kant, believe that some actions are morally wrong, no matter the consequences. Killing an innocent person—no matter how many lives it saves—is always wrong.
In this view, pulling the lever means actively choosing to kill someone, which violates a moral duty not to harm. Doing nothing, while tragic, doesn’t make you morally responsible in the same way.
It’s the difference between letting something bad happen and causing it to happen.
The Fat Man Variant
Now imagine this twist: the trolley is heading toward five people, and this time there’s no lever. But you’re standing on a bridge above the track, next to a large man. If you push him off the bridge, his body will stop the trolley—saving the five people, but killing him.
Would you do it?
Most people who would pull the lever in the first version hesitate here. Why? The outcome is the same—one life for five—but physically pushing someone feels more personal and violent than pulling a lever.
This variation highlights how much our moral judgments depend on intention, proximity, and emotional salience—not just logic.
What This Reveals About Us
Philosophers and psychologists have studied the Trolley Problem for decades, and here’s what they’ve found:
People tend to favor utilitarian choices in impersonal scenarios (e.g., pulling levers).
People lean toward deontological choices in personal scenarios (e.g., pushing someone).
Emotional reactions play a large role in moral reasoning, even when we think we’re being rational.
In short, our ethics are messy—and influenced by more than just reason.
Real-World Applications
While the Trolley Problem is hypothetical, it echoes real ethical dilemmas:
Autonomous Vehicles
If a self-driving car must choose between hitting a pedestrian or swerving and risking its passenger’s life, what should it do? This is a Trolley Problem on wheels.
Medical Triage
Doctors sometimes face decisions about who receives limited life-saving treatment. Saving one patient might mean letting another die. These are real, painful choices.
Military Ethics
Drone strikes and wartime decisions often involve weighing the lives of civilians against military targets. How do we calculate acceptable loss?
Each of these cases brings trolley-like tradeoffs into the real world—often with lives on the line and no time for philosophy class.
Philosophical Variations
Over the years, dozens of Trolley Problem variants have emerged:
Loop Track: The diverted track loops back onto the main track. The person on the side track is large enough to stop the trolley, but only if it hits them first.
Organ Transplant: A surgeon has five patients in need of organs. Should they kill a healthy patient to save five? (Most say no—despite the math being the same.)
Lazy Susan: A spinning platform randomly switches the tracks. Would you let chance decide?
These versions test our intuitions and show how fragile our ethical principles can be under pressure.
Neuroscience Meets Ethics
Recent studies using brain imaging show that different types of moral decisions activate different areas of the brain:
Emotional reasoning (like pushing the fat man) activates the limbic system.
Rational cost-benefit thinking (like pulling the lever) activates prefrontal regions.
This suggests we use dual systems—emotion and reason—in moral judgment. It’s not just about logic. It’s about being human.
Criticisms of the Trolley Problem
Not everyone loves the trolley.
Critics argue that:
It’s too simplistic and unrealistic.
It forces binary decisions, ignoring complex social dynamics.
It ignores systemic causes of harm (like inequality or infrastructure).
It may lead to cold utilitarian logic in real-life policy.
Still, even critics agree that the Trolley Problem provokes meaningful questions—and helps clarify our moral instincts.
Pop Culture and Influence
The Trolley Problem has made its way into:
The Good Place (TV): Chidi literally faces a trolley dilemma—and freezes.
Ethics 101 courses: It’s a classroom staple.
Memes: Yes, even ethics gets meme-ified.
Its simplicity makes it endlessly remixable. Its depth makes it unforgettable.
Glossary of Terms
Utilitarianism: Ethical theory that promotes actions that maximize overall happiness or minimize suffering.
Deontology: Ethics based on duties and principles, regardless of consequences.
Moral Dilemma: A situation where every available choice involves some form of wrongdoing or harm.
Intention vs. Consequence: The debate over whether actions are judged by what they aim to do, or by what they actually cause.
Discussion Questions
Is it more ethical to act and cause harm, or to do nothing and allow greater harm?
Does emotional distance change the morality of a decision?
How should we design policies or technologies that involve trolley-like tradeoffs?
References and Further Reading
Foot, Philippa. “The Problem of Abortion and the Doctrine of the Double Effect” (1967)
Thomson, Judith Jarvis. “Killing, Letting Die, and the Trolley Problem” (1976)
Stanford Encyclopedia of Philosophy – The Trolley Problem
MIT Media Lab – Moral Machine: Explore how people across cultures respond to trolley-like dilemmas
Greene, Joshua. Moral Tribes: Emotion, Reason, and the Gap Between Us and Them