Questions hidden inside
- Is redirecting an existing threat morally different from creating a new threat?
- Should saving the greater number outweigh a person's claim not to be deliberately harmed?
- Why do judgments change when the physical details change but the number of lives does not?
Philosophical lenses
Consequences
How many people are harmed or saved?
Outcome-focused reasoning gives strong weight to reducing total harm, while still needing to consider uncertainty, precedent, and wider effects.
Rights and constraints
What may one person do to another?
Rights-based approaches ask whether some actions remain impermissible even when violating a constraint would produce a better total outcome.
Agency
What is the difference between acting and allowing?
The case tests whether redirecting danger, intending harm, foreseeing harm, and failing to intervene carry different moral significance.
Begin with a choice
A runaway trolley will strike five people unless you pull a switch that redirects it toward one person. What should you do?
The scenario
A runaway trolley is moving toward five people who cannot leave the track. You stand beside a switch that can send the trolley onto another track, where one person is unable to escape.
You did not create the danger, and there is no time to stop the trolley in another way. Pulling the switch will predictably save the five and expose the one person to the threat.
What the experiment is for
The case separates considerations that often point in the same direction: producing a better outcome, respecting each person, avoiding direct involvement in harm, and responding to an emergency.
It does not establish that ordinary moral decisions can be solved by counting lives. Its value lies in making competing reasons visible and allowing carefully changed versions to test which features drive a judgment.
Arguments and objections
An outcome-focused argument favors pulling the switch because one death is a lesser harm than five. A constraint-based objection asks whether an innocent person may be made to bear a danger for the benefit of others, even when the threat is redirected rather than created.
The distinction between doing and allowing harm may support refusing to intervene, but critics argue that knowingly permitting preventable deaths is also an exercise of agency. The intended-versus-foreseen distinction adds another dispute: the one person's death may be predicted without being the goal or method of saving the five.
| Consideration | Reason to pull | Reason not to pull |
|---|---|---|
| Total harm | One death is less harmful than five | Numbers may not override individual constraints |
| Agency | Intervention prevents avoidable deaths | Pulling makes the agent part of the harmful sequence |
| Intention | The aim is saving five, not killing one | Foreseeable lethal harm still requires justification |
| Rights | Each person's loss matters equally | The one person has not consented to bear the redirected threat |
What the case leaves out
Real emergencies include uncertainty, incomplete information, institutional roles, histories of responsibility, and alternatives that the simplified case removes. Those omissions make the thought experiment clearer, but also limit direct application.
Different variants can reveal unstable intuitions rather than a single hidden rule. A responsible conclusion should explain which feature matters and why, instead of treating an immediate reaction as proof.
- Change whether the harm is redirected or used as the means of stopping the trolley.
- Change whether the decision-maker helped create the danger.
- Change the certainty of the predicted outcomes.
- Ask what rule or institution would govern repeated cases.
Change one fact
Does making the person's death part of the method change your judgment?
Your earlier choice: Pull the switch because redirecting the trolley will save five people at the cost of one life.
Continue with moral responsibility, justice, value.
Continue with Ada
Professor Ada Rowan
Test an idea or objection
Compare perspectives, test an assumption, or develop an objection using this reviewed page as context.
Related paths
Sources
- The Trolley Problem — Judith Jarvis Thomson (1985)
Thomson’s influential paper develops and compares trolley, transplant, and related cases to test distinctions among rights, harming, using a person as a means, and redirecting threats. It is a primary source for later versions of the trolley problem rather than the sole origin of the broader family of cases.
View source - Doing vs. Allowing Harm (2025)
Detailed survey of whether doing harm differs morally from allowing harm, including action and omission, rights, causation, intention, trolley cases, and challenges to simple classifications. It supports trolley-problem content and unintended-consequence discussions.
View source - Doctrine of Double Effect — Alison McIntyre (2023)
Scholarly source for evaluating actions that have both beneficial and harmful effects, especially the debated moral distinction between harm intended as an end or means and harm foreseen as a side effect.
View source - Deontological Ethics — Larry Alexander; Michael Moore (2024)
Authoritative overview of duty-based theories that assess choices through constraints, permissions, obligations, agency, rights, and the distinction between intending harm and merely allowing or foreseeing it.
View source - Consequentialism — Walter Sinnott-Armstrong (2023)
Scholarly survey of consequentialist theories and their variations, including what consequences count, whose good matters, actual versus expected results, act and rule approaches, and major objections involving rights, justice, and demandingness.
View source
Last modified 2026-07-30. Reviewed by Thinking Paths editorial team.