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If your self-driving Volvo suddenly must decide whether to swerve into one pedestrian in order to avoid crashing into five others, what should it do? The thought experiment known as the “trolley problem” – long invoked in controversies from bioethics to capital punishment to climate change – has enjoyed a recent surge of attention, thanks to its uncanny resemblance to choices that driverless cars may have to face. In this essay, first I review Frances Kamm’s book, The Trolley Problem Mysteries, which reveals the unsettled state of philosophical debates about this classic dilemma. Next I report findings from randomized experiments I conducted, addressing this basic question: Can our intuitions about such moral dilemmas be influenced by the presence of the law? The findings suggest that the law can indeed exert an influence over our moral intuitions about the trolley problem. Telling subjects that turning the trolley (sacrificing one life to save more lives) constitutes criminal homicide increases the number who say that doing so is morally prohibited. In comparison, telling subjects that the law requires minimizing casualties during such accidents reduces the number who say that turning the trolley is morally prohibited; it also increases the number who say that doing so is morally required. Moreover, the content of the law can influence moral intuitions even when subjects are told that it will not be enforced. This evidence motivates further inquiry into the feedback loops between our moral intuitions and the law (what if the moral intuitions we can observe have already been shaped by people’s impressions, however vague or subconscious, about what the law expects?) and into the potential mechanisms of the law’s halo (do people sometimes look to the law as a source of moral guidance – and if so, when?).


Law | Law and Philosophy | Law and Society


Book Review
The Trolley Problem Mysteries by F.M. Kamm, New York, NY: Oxford University Press, 2015, pp. xi, 270, $29.95.