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Autonomous Cars: In Favor of a Mandatory Ethics Setting


The recent progress in the development of autonomous cars has seen ethical questions come to the forefront. In particular, life and death decisions regarding the behavior of self-driving cars in trolley dilemma situations are attracting widespread interest in the recent debate. In this essay we want to ask whether we should implement a mandatory ethics setting (MES) for the whole of society or, whether every driver should have the choice to select his own personal ethics setting (PES). While the consensus view seems to be that people would not be willing to use an automated car that might sacrifice themselves in a dilemma situation, we will defend the somewhat contra-intuitive claim that this would be nevertheless in their best interest. The reason is, simply put, that a PES regime would most likely result in a prisoner’s dilemma.

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Fig. 1


  1. 1.

    Henceforth, we will use the terms autonomous car, robot car and self-driving car interchangeably.

  2. 2.

    This is according to the data of the Insurance Institute for Highway Safety. Note that the traffic-related death rate per 100,000 inhabitants is lower for first world countries due to safer (newer) technology, functioning regulation and enforcement of traffic laws.

  3. 3.

    We emphasize the normative point here, since there might be other perspectives from which the introduction of autonomous cars seems to pose a problem. People who enjoy having a steering wheel in their hand might fear, for instance, that autonomous cars will prove so much safer than regular cars that Elon Musk’s prediction comes true and the government might outlaw non-autonomous cars (Hof 2015).

  4. 4.

    This scenario is based on Millar’s tunnel problem (Millar 2014a). Marcus (2012) and Goodall (2013) give a similar scenario called the “bridge scenario”.

  5. 5.

    In this paper we will not discuss the trolley problem in detail. Readers who are not familiar with the thought experiment are referred to Foot (1967), Thomson (1976) and Thomson (1985). For a complete overview see Robinson (2014).

  6. 6.

    One could argue that the manufactures could come together and agree on industry standards. There are two things to say to this. First, industry-wide standards are pretty hard to achieve in a globalized world with important car manufacturers all over the globe. Second, it is especially difficult if the industry standards do not reflect the preferences of consumers.

  7. 7.

    In this case, the expected value equals the expected number of deaths.

  8. 8.

    Unfortunately, we cannot debate the various ways in which such a maxim could be implemented. Although this maxim, on the face of it, seems quite simple, the implementation will surely raise many morally relevant follow-up questions. For instance, how should we weight lives? Should one person count equally regardless of, say, their age? Furthermore, who should count as ‘all people affected’—should this include just motorized participants in traffic or should this also include pedestrians?

  9. 9.

    However, note that our approach is contractarian by nature.

  10. 10.

    It should be noted, though, that the data just weekly confirms our argument. The reason is that there is a difference between what an individual deems as the right course of conduct and whether she wants that particular course of action to become a law that is applied to everyone.

  11. 11.

    An interesting question that arises from this line of argument would be whether a MES would incentivize people to car-share to minimize their risk of being targeted. The answer to that depends on many variables, for instance, to what degree people value time alone. From an ecological perspective, an incentive to carpool would surely not be a bad thing. Furthermore, more carpooling or the use of public transportation would mean less traffic, and less traffic might decrease the possibility of accidents. On the other hand, people could choose to pay people to accompany them in their cars to increase their safety. While this is not impossible, it seems highly unlikely to play a role.

  12. 12.

    For that reason we are also highly skeptical of Millar’s suggestion to apply ethical norms from medicine and bioethics to the case of autonomous cars.

  13. 13.

    We want to express our gratitude towards two anonymous reviewers who brought this point to our attention.


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Correspondence to Jan Gogoll.

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Gogoll, J., Müller, J.F. Autonomous Cars: In Favor of a Mandatory Ethics Setting. Sci Eng Ethics 23, 681–700 (2017).

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  • Autonomous driving
  • Automation
  • Ethics
  • Morality
  • Dilemma