Tramway Problem

The Trolley Problem is a thought experiment in ethics and moral philosophy that examines the conflict between the majority’s right to life and the minority’s right to life. It has been the subject of extensive research for nearly half a century across multiple disciplines including psychology neuroscience ethics and law. At its core the problem questions whether it is morally permissible to divert a runaway trolley from a track where it will kill five people onto another track where it will kill one person instead.

Underlying the problem are two sub-questions: one descriptive and the other normative. The descriptive question seeks to understand why people make different moral judgments in situations that are similar in terms of aims and outcomes—for example switching a lever to sacrifice one person versus a surgeon sacrificing one person to save five through organ transplantation. The normative question investigates whether it is permissible to sacrifice an innocent minority’s life to save the majority and if so under what conditions this might be justified.

Five Lives Against One Life (Generated by Artificial Intelligence)

Historical Development

The first formulation of the trolley problem appeared in 1967 in British philosopher Philippa Foot’s paper titled “The Problem of Abortion and the Doctrine of the Double Effect.” In this work Foot used the dilemma of a runaway trolley driver who could divert the trolley from a track with five workers onto another track with one worker as an example to discuss the Doctrine of the Double Effect (DDE).

However it was American philosopher Judith Jarvis Thomson who named developed and popularized the problem. In her 1976 article “Killing Letting Die and The Trolley Problem” and her 1985 article “The Trolley Problem” Thomson introduced new scenarios such as the “fat man case” and the “loop variant” thereby complicating the problem and establishing it as a central topic in philosophical literature. Since then the trolley problem has become a standard thought experiment for testing deontological ethical theories.

Core Scenarios and Variants

Several key scenarios form the basis for understanding the trolley problem:

The Switch Case

A runaway trolley is headed toward five workers on the track. An observer can flip a nearby lever to divert the trolley onto another track where one worker is present. Flipping the lever will save the five workers but cause the death of the one worker. Empirical studies indicate that the vast majority of people approximately 90 percent regard flipping the lever as morally permissible in this scenario.

The Fat Man / Footbridge Case

Similar to the first scenario a runaway trolley is headed toward five people. This time the observer stands on a footbridge above the tracks beside a very heavy man whose weight is sufficient to stop the trolley. The observer can push the man off the bridge onto the tracks thereby saving the five people but causing the death of the fat man. In this scenario the vast majority of people approximately 90 percent consider pushing the man to be morally wrong.

The Transplant Surgeon Case

Often presented as an alternative to the fat man case a successful organ transplant surgeon has five patients each in need of a different organ and all will die without transplants. At that moment a healthy young man comes to the clinic for a routine checkup and is found to be a tissue match for all five patients. The surgeon could kill the healthy man and harvest his organs to save the five patients. In this case nearly everyone agrees that the surgeon’s action would be morally unacceptable.

The Loop Variant

• In this variant the second track to which the trolley is diverted loops back and reconnects with the main track. If no one were on the second track the trolley would circle back and kill the five workers. However on the second track is a fat man whose body is large enough to stop the trolley. In this case turning the lever makes it more explicit that the fat man’s presence is being used as a means to save the five thereby testing theories such as the Doctrine of the Double Effect.

Theoretical Approaches

Solutions to the trolley problem are typically framed within consequentialist and deontological ethical theories.

Consequentialist Approach

According to consequentialist or utilitarian ethics the moral rightness of an action is determined by its outcomes. In the simplest utilitarian calculation the action that saves the greatest number of lives is the morally correct one. From this perspective five lives are more valuable than one so sacrificing one person to save five is not only morally permissible but may even be obligatory in both the switch case and the fat man case. Thus within a purely consequentialist framework there is no genuine “problem” or contradiction in the trolley scenario.

Deontological Approaches

Deontological theories evaluate the morality of actions based on adherence to specific moral rules principles or duties regardless of consequences. The trolley problem serves as a central test case for these approaches.

Doctrine of Double Effect (DDE)

This doctrine which traces back to Thomas Aquinas draws a moral distinction between an intended outcome and a merely foreseen side effect. According to this doctrine it may be permissible to allow a harmful outcome as an unintended side effect but it is not permissible to intentionally use that harmful outcome as a means to achieve a good end.

• Application: In the switch case the death of one worker is not the direct aim of the action but only a foreseen side effect of diverting the trolley. In the fat man or transplant surgeon cases however the victim’s death is intentionally used as a means to save the five; without the victim’s body the rescue would fail. This distinction attempts to explain the intuitive moral difference between the two scenarios.

Distinction Between Negative and Positive Duties (Philippa Foot)

In her own solution Foot draws a distinction between negative duties—the duty not to interfere or cause harm—and positive duties—the duty to help others. Foot argues that negative duties are stronger and take priority over positive duties.

• Application: The transplant surgeon case presents a conflict between the negative duty not to kill and the positive duty to save five lives. The stronger negative duty not to kill prevails. The switch case however can be seen as a conflict between two negative duties—to kill one person or to kill five—and in such cases the action causing less harm is preferred.

Violation of Rights and the Redirecting of Threat (Judith Jarvis Thomson)

In her 1985 work Thomson attempted to explain the problem in terms of rights. Her hypothesis holds that redirecting an existing threat from a larger group to a smaller one may be permissible provided that the act of redirection itself does not violate the victim’s fundamental rights.

• Application: In the switch case the threat (the trolley) is redirected by flipping the lever. The act of flipping the lever does not itself constitute a rights violation. In the fat man case however the threat is redirected by pushing the man. Pushing someone without consent is itself a direct rights violation. This distinction aims to explain the moral difference between the two cases.

Psychological and Neurological Findings

fMRI (functional magnetic resonance imaging) studies conducted by Joshua Greene and colleagues have investigated the neural basis of moral responses to the trolley problem. These studies show that different scenarios activate distinct regions of the brain:

• Personal dilemmas such as the fat man case which involve direct physical force trigger greater activity in brain regions associated with emotion such as the medial frontal gyrus.

• Impersonal dilemmas such as the switch case which involve indirect action trigger greater activity in brain regions associated with cognitive control and logical reasoning such as the parietal lobe.

These findings suggest that the intuitive moral difference between the two scenarios arises from distinct cognitive and emotional processes.

Evaluation from the Perspective of Criminal Law

Because the trolley problem centers on the right to life it also falls within the scope of criminal law. The question “How should I act to avoid violating the law?” is addressed through legal doctrines such as necessity (state of necessity) and conflict of duties.

• State of Necessity (TCK Art. 25/2): This refers to a situation in which a person commits an act proportional to the gravity of a serious and inevitable threat to a right belonging to themselves or another. In Turkish law there is debate over whether necessity constitutes a justification (lawful act) or merely an excuse (removal of fault). However in conflicts between rights to life the notion that one life is quantitatively superior to another is problematic especially when grounded in the concept of human dignity.

• Conflict of Duties: This approach frames the problem as a situation in which an agent faces multiple legal duties that cannot be fulfilled simultaneously. In the trolley problem this conflict arises between the negative duty not to kill (TCK Art. 81) and the positive duty to assist the five endangered persons (TCK Art. 98).

In both Turkish and German criminal law doctrines the general tendency is that when equal legal interests such as rights to life conflict the negative duty not to cause harm takes precedence over the positive duty to help. This is because actively causing harm is considered a more serious injustice than failing to prevent harm. This distinction is also reflected in sentencing: the penalty for intentional killing is significantly heavier than the penalty for failing to fulfill a duty to assist.

According to this legal framework actively sacrificing an innocent minority to save the majority is unlawful. Therefore from a strict criminal law perspective the interventions described in most trolley scenarios (switching the lever pushing the fat man etc.) would be considered unjustified. As a result there may be no genuine “problem” or moral dilemma in the philosophical sense under this legal framework.