In this commentary, I will argue that Levine et al. understate the range of folk moral judgments that cannot be easily explained by their contractualist theory of moral cognition, and on the flipside, overstate the range of moral judgements that cannot be easily explained by rival deontological or consequentialist theories of moral cognition. In particular, I will argue that folk moral judgments about future generations and nonhuman animals cannot be easily explained by resource-rational contractualism.

Levine et al. themselves concede that “we sometimes feel moral commitments to people beyond what a contractualist approach would seem to demand” – such as to distant strangers or our own children. Levine et al. suggest that feelings of special moral obligation toward one’s own children can be explained by kin partiality impinging upon our core contractualist moral psychology. Furthermore, they also suggest that beneficence toward distant strangers can be explained by (1) heuristic generalizations of contractualist agreements, which “overextend moral concern to others where it is not warranted by the logic of bargaining” and (2) a desire to “signal one’s favorable qualities as a social partner” to nearby strangers.

Unfortunately, though, none of these strategies is particularly promising for explaining our moral judgments about nonhuman animals. Folk judgments about animal ethics have many features in common with our folk judgments about the ethical treatment of human beings. For instance, most people seem to judge that there are deontological constraints against harming some animals in order to benefit others, analogous to (although somewhat weaker than) the deontological constraints against harming some human beings in order to benefit others (Caviola et al., Reference Caviola, Kahane, Everett, Teperman, Savulescu and Faber2021; Kahane & Caviola, Reference Kahane and Caviola2023). Thus, we should expect any adequate theory of our core interpersonal moral psychology to also be able to explain our folk judgments about animal ethics.

However, it is difficult to see how our judgments about animal ethics can be explained by “the principle of finding mutually beneficial agreements under resource constraint.” After all, the folk routinely judge that it can be morally wrongful for a human being to harm animals regardless of whether or not that person could expect to have any sort of cooperative relationship with the animals. Moreover, it is difficult to imagine that our ethical judgments about harming squirrels or tigers (say) could be heuristic overgeneralizations of bargains that we’ve struck with nearby human beings, or else ways of signaling a willingness to cooperate with other nearby humans.

Likewise, it is difficult to see how any of Levine et al.’s explanatory strategies could be extended to account for folk judgments about population ethics. We sometimes make moral judgments about actions that will only affect generations living well after our own deaths. The empirical evidence suggests that these judgments are complex and multi-factoral (Caviola et al., Reference Caviola, Althaus, Mogensen and Goodwin2022; Law et al., Reference Law, Syropoulos, Coleman, Gainsburg and O’Connor2024; Schubert et al., Reference Schubert, Caviola, Savulescu and Faber2024) – so exactly the sort of moral judgments that we should expect a theory of our core moral psychology to supply an account of. However, it is not clear what future generations could do to harm or benefit present generations in a bargain for mutual advantage. And it would be implausible to suggest that all of our population ethical judgments are (for instance) just extensive overgeneralizations of some other contractualist bargains.

(A caveat: some philosophers have argued that we can be “posthumously” harmed and benefitted by future generations [Boonin, Reference Boonin2019]. However, it strikes me as implausible to suppose that many folk judgments about population ethics implicitly presuppose this possibility for posthumous changes to our wellbeing. Hence, it remains unclear whether resource-rational contractualism can account for our folk judgments.)

This concludes my argument for the claim that Levine et al. understate the range of everyday moral judgments that cannot be easily explained by resource-rational contractualism. In the remainder of this commentary, I will now point out a couple of places where Levine et al. also overstate the range of moral judgments that cannot be easily explained by deontological and consequentialist theories of moral cognition.

Firstly, Levine et al. report that when presented “with a hypothetical situation in which somebody is able to earn a large sum of money by painting their neighbor’s house blue while the neighbor cannot be contacted,” study participants judged (Levine et al., Reference Levine, Kleiman-Weiner, Chater, Cushman and Tenenbaum2024) that “accepting the money is permissible if a sizeable enough portion is given to the neighbor.” Levine et al. suggest that these judgments cannot be well-modeled by deontological theories of moral cognition (Levine et al., Reference Levine, Kleiman-Weiner, Chater, Cushman and Tenenbaum2024). However, I suspect that these judgments could in fact be well-modeled by deontological theories of moral cognition which incorporate the familiar notion of hypothetical consent (Kuflik, Reference Kuflik2009). According to these versions of deontology, if I am not in a position to ask my neighbor for her consent to deface her property, then it might (nonetheless) be permissible for me to do so as part of a sequence of actions which I have reason to believe my neighbor would give her consent to.

Levine et al. also suggest that “current theories of moral psychology fall short of explaining … how, when, and why people will exhibit moral flexibility” by revising existing moral rules or norms. However, I suspect that rule consequentialism could explain this phenomenon just as well as contractualism could. For instance, a rule consequentialist theorist of moral cognition could suggest that it is morally appropriate to attempt to revise an established moral rule if and only if we have reason to believe that the expected benefits of revising this rule would outweigh all of the associated transition costs and risks.

In summary, then, Levine et al. need to say more to defend their suggestion that resource-rational contractualism fares better than its rivals with respect to the desideratum of providing a unified explanation for “the apparently fragmentary nature of our moral psychology.”