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Sunday, August 13, 2023

Beyond killing one to save five: Sensitivity to ratio and probability in moral judgment

Ryazanov, A.A., Wang, S.T, et al. (2023).
Journal of Experimental Social Psychology
Volume 108, September 2023, 104499


A great deal of current research on moral judgments centers on moral dilemmas concerning tradeoffs between one and five lives. Whether one considers killing one innocent person to save five others to be morally required or impermissible has been taken to determine whether one is appealing to consequentialist or non-consequentialist reasoning. But this focus on tradeoffs between one and five may obscure more nuanced commitments involved in moral decision-making that are revealed when the numbers and ratio of lives to be traded off are varied, and when the probabilities of each outcome occurring are less than certain. Four studies examine participants' reactions to scenarios that diverge in these ways from the standard ones. Study 1 examines the extent to which people are sensitive to the ratio of lives saved to lives ended by a particular action. Study 2 verifies that the ratio rather than the difference between the two values is operative. Study 3 examines whether participants treat probabilistic harm to some as equivalent to certainly harming fewer, holding expected ratio constant. Study 4 explores an analogous issue regarding the sensitivity of probabilistic saving. Participants are remarkably sensitive to expected ratio for probabilistic harms while deviating from expected value for probabilistic saving. Collectively, the studies provide evidence that people's moral judgments are consistent with the principle of threshold deontology.

General discussion

Collectively, our studies show that people are sensitive to expected ratio in moral dilemmas, and that they show this sensitivity across a range of probabilities. The particular kind of sensitivity to expected value participants display is consistent with the view that people's moral judgments are based on one single principle of threshold deontology. If one examines only participants' reactions to a single dilemma with a given ratio, one might naturally tend to sort participants' judgments into consequentialists (the ones who condone killing to save others) or non-consequentialists (the ones who do not). But this can be misleading, as is shown by the result that the number of participants who make judgments consistent with consequentialism in a scenario with ratio of 5:1 decreases when the ratio decreases (as if a larger number of people endorse deontological principles under this lower ratio). The fact that participants make some judgments that are consistent with consequentialism does not entail that these judgments are expressive of a generally consequentialist moral theory. When the larger set of judgments is taken into account, the only theory with which they are consistent is threshold deontology. On this theory, there is a general deontological constraint against killing, but this constraint is overridden when the consequences of inaction are bad enough. The variability across participants suggests that participants have different thresholds of the ratio at which the consequences count as “bad enough” for switching from supporting inaction to supporting action. This is consistent with the wide literature showing that participants' judgments can shift within the same ratio, depending on, for example, how the death of the one is caused.

My summary:

This research provides new insights into how people make moral judgments. It suggests that people are not simply weighing the number of lives saved against the number of lives lost, but that they are also taking into account the ratio of lives saved to lives lost and the probability of each outcome occurring. This research has important implications for our understanding of moral decision-making and for the development of moral education programs.