Conclusion
Discoveries in moral psychology can undermine, and support, ethical principles if either or both of Foot’s or Kamm’s broad approaches are not entirely misguided. Does this mean Kant (1870, p. AK 4:425–6) was wrong? Not obviously. If we adopt Thomson’s other method of trolley cases, we have yet to find a role for discoveries in moral psychology. Nor do arguments from framing effects appear sufficient to establish that discoveries in moral psychology are ethically relevant (contra Rini, 2013 and Sinnott-Armstrong, 2008). But perhaps our perspective will change when we attempt to gain a deeper understanding of the psychology of ethical judgements.
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Notes
Empirical claims on which discoveries in moral psychology bear are directly involved in some ethical arguments, including those offered by Foot, Singer and Kamm (see Foot and Trolley Cases: Kant Was Wrong and Singer vs Kamm on Distance).
Recent philosophical discussion has tended to focus on the use of discoveries in moral psychology for supporting very general arguments aimed at showing moral intuitions are not justified (for example, Königs, 2020; Rini, 2016; Kumar & Campbell, 2012; Sandberg & Juth, 2011; see Debunking Arguments). Such discussions typically conclude that discoveries in moral psychology have little or no significance for ethics.
It may be correct that the very general arguments considered do not yield substantive new ethical knowledge. But in this lecture we have seen how examining particular ethical arguments points to a different conclusion. Discoveries in moral psychology can be important, in a direct and straightforward way, to evaluating some arguments in ethics.
Glossary
According to Sinnott-Armstrong, Young, & Cushman (2010, p. 256), moral intuitions are ‘strong, stable, immediate moral beliefs.’