The provocative and interesting claim by Fitouchi et al. is that we moralize certain seemingly harmless acts – laziness, overeating, unruly music and dance, and so on – because we believe that they are risk factors for future poor cooperation, because they erode self-control. This theory suggests that people who lack certain beliefs about self-control should not exhibit this kind of puritanical morality, and conversely, people who don't exhibit a puritanical morality should be less concerned about issues of self-control. The authors review one such case study in their discussion of western, educated, industrialized, rich, and democratic (WEIRD) societies, and suggest that people within these societies are less concerned with puritanical morality because they see one another as overall more self-controlled and trustworthy, and thus less susceptible to the eroding forces of gluttony and sloth.

Here, I propose that an even better test case for their theory is a diametrically opposite group, one deeply lacking in self-control, and strongly prone to hedonistic behavior – namely, young children. The cluster of folk-psychological beliefs that the authors focus on – including the notions that cooperation requires self-control, that hedonistic behavior erodes self-control, and that self-control can be trained by repeated practice – is unlikely to be innate, and instead, emerge slowly throughout childhood (Duckworth, Gendler, & Gross, Reference Duckworth, Gendler and Gross2014). Two predictions arise from this (or, equivalently, two ways to falsify their theory). First, prior to the development of these folk-psychological beliefs, children should be untroubled by what (many) adults would see as violations of puritanical morality. Children do possess a moral sense, and from a very young age they are bothered by acts that they see as harmful or unfair (e.g., Bloom, Reference Bloom2014; Woo, Tan, & Hamlin, Reference Woo, Tan and Hamlin2022), but they should lack a puritanical morality. Second, once these folk-psychological views are in place, they should have the same puritanical morality that adults do.

Are these predictions supported? There is a rich body of research into children's beliefs about self-control, choice, and inner conflict (for a recent review, see Wente, Zhao, Gopnik, Kang, & Kushnir, Reference Wente, Zhao, Gopnik, Kang, Kushnir and Mele2020). Some studies find that mature folk beliefs in this domain are slow to develop. For instance, children fail to understand that one person might have conflicting or mixed desires until the age of 7 or 8 (e.g., Choe, Keil, & Bloom, Reference Choe, Keil and Bloom2005; Harris, Reference Harris1989; Harter & Buddin, Reference Harter and Buddin1987; Lagatutta, Reference Lagattuta2005). But other studies with simpler tasks and more explicit forced choices find even 4-year-olds can identify mixed emotions (Kestenbaum & Gelman, Reference Kestenbaum and Gelman1995) and 6-year-olds affirm that people can act against their stated desires (Kushnir, Gopnik, Chernyak, Seiver, & Wellman, Reference Kushnir, Gopnik, Chernyak, Seiver and Wellman2015). Finally, metacognitive knowledge about self-control strategies (such as the effectiveness of removing a tempting marshmallow from one's field of view) improves gradually between the ages of 4 and 12 (Mischel & Mischel, Reference Mischel and Mischel1983). This is all relevant to the claims in the target article, however, there is as yet little known about whether children see self-control as a capacity that can be nurtured or eroded, and whether they see it as related to cooperation.

Similarly, although there is some research exploring the emergence of a disgust-based morality in young children (finding, for the most part, that it tends to emerge relatively late, e.g., Aznar, Tenenbaum, & Russell, Reference Aznar, Tenenbaum and Russell2023; Rottman & Kelemen, Reference Rottman and Kelemen2012), the developmental emergence of a puritanical morality is more of an open question. When do young children come to believe that it's wrong to overindulge in Halloween candy or sleep until noon on a weekend? (And do their moral intuitions differ when they are judging themselves, other children, or adults?)

The answers to the interesting questions raised by the target article need not be all-or-none. Perhaps children have a different conception of the relationship between self-control, hedonistic behavior, and cooperation than adults do; if Fitouchi et al. are right, this should lead to a correspondingly different conception of puritanical morality.

My own work hints at one aspect of this different conception. In Starmans and Bloom (Reference Starmans and Bloom2016), 3- to 8-year-old children, as well as a group of adults, were told two stories. Both stories described a child performing a morally good action (e.g., keeping a promise, telling the truth, helping someone). In one story, the character struggled with the decision to act morally, because she was tempted by other options, like going out to play, but also wanted to do the right thing. Ultimately, she acted morally even though it was difficult for her, thus displaying self-control. In the other story, the character was not tempted to do otherwise, and so self-control was not required. After hearing both stories, children and adults were asked which character they thought was more morally good.

The findings revealed a striking developmental difference: Not surprisingly, adults had the intuition that the individual with self-control, who overcame their struggle with temptation, was morally better. But children's judgments were strongly in the opposite direction. When the outcome is held constant, children judge someone who does the right thing without experiencing any inner struggle to be morally superior to someone who does the right thing through the use of self-control. This developmental difference remained consistent when participants were asked who should be rewarded, who is morally superior, and who will act morally in the future.

This suggests that an appreciation of the value of exercising willpower and self-control is late-emerging (see Zhao & Kushnir [Reference Zhao and Kushnir2022] for replication and extension). The theory proposed by Fitouchi et al. does not necessarily entail that these children must therefore lack a puritanical morality, but the findings reviewed above suggest that this is a prediction the authors might want to make. If this prediction holds – and, more generally, if a puritanical morality emerges very late in development, alongside the emergence of adult-like beliefs about self-control – it would provide considerable support for their intriguing theory.