Who would sacrifice one person in order to save five? – Global differences when it comes to making moral decisions

A study presented 70,000 participants in 42 different countries with moral dilemmas

January 21, 2020

The degree to which people are willing to sacrifice a single individual in order to save several others differs from one country to another. A scientific study of 70,000 participants from 42 countries conducted by a research team led by Iyad Rahwan, Director of the Center for Humans and Machines at the Max Planck Institute for Human Development indicates that worldwide, there are areas of commonality and difference when it comes to making moral decisions. The results of the study have been published in the journal PNAS.

Is it acceptable to sacrifice one person in order to save the lives of several others? This question has been the subject of debate among philosophers, ethicists and legal experts for decades, with reference to a well-known moral thought experiment: the trolley problem. A “trolley” (tram) is traveling towards five men working on the track, and is not braking. The person manning the points could divert the trolley to a side track, on which just one person is working. Should the points operator sacrifice one person in order to save five?

 “During the course of the debate surrounding autonomous vehicles, the trolley problem has been revived. How should self-driving vehicles behave if an accident cannot be prevented? Should the vehicle swerve to avoid a group of people, but kill the passengers in the car while doing so?” As Iyad Rahwan, Director of the Center for Humans and Machines at the Max Planck Institute for Human Development explains, “There are no universal basic principles to guide engineers and programmers of autonomous vehicles.” The large Moral-Machine Survey, which Iyad Rahwan and his team at the Massachusetts Institute of Technology conducted in 2017, also shows that people would program autonomous vehicles in different ways in situations of this kind, depending on their cultural milieu.

While their earlier work focused on autonomous vehicle accidents, Iyad Rahwan and his team now turned back to the classic versions of the Trolley Problem. This is important because, despite the large public interest in autonomous vehicle accident dilemmas, the classic Trolley Problem is much better understood among philosophers and psychologists. To this end, they have analyzed decisions made by 70,000 participants from 42 countries relating to three variants of the trolley problem.

In the first scenario, the classic trolley problem, participants were able to pull the switch and divert the wagon to a side track. One person working on the side track dies, while five others on the main track are saved. In the second scenario, the side track loops back onto the main track on which the five people are working. Pulling the switch leads to the death of the person working on the side track. However, his body prevents the wagon from rolling back onto the main track. Unlike the first scenario, the death of one individual is not only taken into account, but is necessary in order to save the lives of the other five. In the third scenario, one large man can be knocked off a pedestrian bridge onto the tracks, as a result of which his body stops the wagon and saves five other people. Here, too, the death of one individual is not only taken into account, but is necessary.

By comparison, in all countries, more participants were willing to sacrifice one person’s life in the first scenario than in the second, while the smallest number were willing to do so in the third scenario. The willingness to take into account the death of one person in order to save others is greater worldwide than the willingness to instrumentalize the death of an individual, as would be the case in the second and third scenarios.

However, there were differences between the countries when it came to the general willingness to sacrifice peoples’ lives. In the first scenario, for example, 82 percent of Germans would approve of sacrificing the individual person, and the values are similar in most western countries. It is only in some east Asian countries that the degree of willingness to sacrifice one human life in order to save the lives of several others is noticeably lower. In China, for example, just 58 percent of participants would approve of pulling the switch in the first scenario. In the third scenario, the responses from the different countries deviate more widely. Thus, 49 percent of participants in Germany would approve of knocking the large man off the pedestrian bridge, while in Vietnam, that figure is 66 percent, and is a mere 32 percent in China.

The researchers discovered a noticeable connection in relation to other aspects of life that are particular to individual countries. In countries where it is difficult to forge new relationships beyond traditional social constructs such as family or work, the degree of willingness to sacrifice one human life is lower. The scientists assume that people shrink from making controversial and unpopular decisions when they are afraid of losing their current relationships. “People may worry that they might be perceived as ‘monsters’ if they are willing to sacrifice a person's life for the greater good. It is still too early to draw a clear, causal link between people's culture-specific moral choices and the ease with which they can form new relationships. However, there is growing evidence that how reputation is cultivated in a particular culture may influence the moral intuitions of the people from this culture.” says Iyad Rahwan.

Original Publication

Awad, E., Dsouza, S., Shariff, A., Rahwan, I., and Bonnefon, J.-F. (2020). Universals and variations in moral decisions made in 42 countries by 70,000 participants. PNAS. https://doi.org/10.1073/pnas.1911517117

The participants can make decisions with respect to three scenarios.

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