The Footbridge Dilemma Reflects More Utilitarian Thinking Than The Trolley Dilemma: Effect Of Number Of Victims In Moral Dilemmas

The Footbridge Dilemma Reflects More Utilitarian Thinking Than The Trolley Dilemma: Effect Of Number Of Victims In Moral Dilemmas Kuninori Nakamura (nakamura.kuninori@gmail.com) Graduate School of Decision Science & Technology, Tokyo Institute of Technology 2-12-1, Ohkayama, Meguro-Ku, Tokyo 152-8552, Japan Abstract Previous studies on moral judgment have assumed that the trolley and footbridge dilemmas (Thomson, 1985) reflect utilitarian and deontologist thinking, respectively. However, on the basis of the “intervention myopia” hypothesis (Waldmann & Dieterich, 2007) and recent findings in analyses of moral dilemmas (Nakamura, 2011), the current study led a somewhat paradoxical prediction: An effect of the manipulation of the number of victims, considered a utilitarian aspect of moral dilemmas, is larger in the footbridge dilemma than in the trolley dilemma. In order to test this prediction, two experimental studies were conducted in which the number of victims in the trolley and footbridge dilemmas were manipulated. Results of the two studies consistently showed an interaction between the dilemma type and the number of victims, thereby indicating that the manipulation of the utilitarian aspect of moral dilemmas has more effect on the footbridge dilemma, which is believed to reflect deontologist thinking. Keywords: trolley dilemma, footbridge dilemma, utilitarian, deontologist Introduction Is it permissible to sacrifice fewer lives to save more? This is a central question in the debate between utilitarianism and deontology. Utilitarians (e.g., Bentham, 1789; 1948) argue that it is indeed permissible because saving more lives results in greater utility for society than saving fewer ones, whereas deontologists (e.g., Kant, 1965) argue that it is not permissible because life is an ultimate right that should not be violated, irrespective of the number benefit yielded by its sacrifice. This debate has drawn the attention of various researchers who have proposed a number of solutions (see e.g., Singer, 1979; Thomson, 1986; Greene & Haidt, 2002; Mikhail, 2009). The philosophical debate between utilitarians and deontologists concerns the normative theory of moral judgment. However, psychologists are interested in the descriptive aspect of moral judgment: are people utilitarian or deontologist? The answer to this question is, surprisingly, “it depends on the context. ” A discrepancy between the trolley and footbridge dilemmas (Thomson, 1985) clearly demonstrates the context dependency in moral judgment. The trolley dilemma can be described in the following manner: A runaway trolley is headed for five people who will be killed if it proceeds on its current course. The only way to save them is to hit a switch that will turn the trolley onto an alternate set of tracks where it will kill one person instead of five. Should one turn the trolley in order to save five people at the expense of one? Most people answer yes to this dilemma. Then, consider a similar problem, the footbridge dilemma. As before, a trolley threatens to kill five people. You are standing next to a large stranger on a footbridge that spans the tracks, in between the oncoming trolley and the five people. In this scenario, the only way to save the five people is to push this stranger off the bridge, onto the tracks below. He will die if you do this, but his body will stop the trolley from reaching the others. Should one save the five others by pushing this stranger to his death? To this question, most people answer no (with regard to precise data, see Greene & Haidt, 2002). With regard to the dominant responses in these dilemmas, people appear to be utilitarians when solving the trolley dilemma and deontologists when solving the footbridge dilemma. In the former dilemma, a person’s choice appears to depend on the number of workmen to be saved, whereas people make much of the right of the man on the bridge in the latter dilemma. Thus, it has been considered that the trolley dilemma reflects the utilitarian way of thinking, whereas the footbridge dilemma reflects the deontologist way of thinking (Greene, Sommerville, Nystrom, Darley, & Cohen, 2001; Waldmann & Dieterich, 2007). With regard to this discrepancy in the dominant responses between the trolley and footbridge dilemmas, various theoretical explanations have been proposed such as the dual process theory (Greene et al., 2001), moral grammar theory (Hauser, 2007; Mikhail, 2009), or causal decision theory (Waldmann & Dieterich, 2007). Although theorists of moral reasoning differ in terms of how to explain the discrepancy between the trolley and footbridge dilemmas, they consistently receive correspondence between the two dilemmas and philosophical way of thinking without any doubt. For example, Greene et al. (2001) said that the dominant response in the footbridge dilemma could be justified in a Kantian (deontologist) vein, but this justification has trouble when considering the trolley dilemma (Greene et al., 2001, p2106). Hauser (2006, p113–4) explained the philosophical implication of the trolley and footbridge dilemmas in terms of whether the utilitarian calculation can justify dominant responses in these dilemmas. Waldmann and Dieterich (2007) also argued that throwing the switch in the trolley dilemma is in line with the utilitarian view, whereas the footbridge dilemma is in line with the deontologist perspective (Waldmann & Dieterich, 2007, p247–8). Although there are differing theoretical explanations for the discrepancy between the trolley and footbridge dilemmas, the theorists in moral reasoning research have no doubt in