The theory proposed by Fitouchi et al. misses the core of puritanical morality: Cruel punishment for harmless actions. Punishment is mutually harmful, unlike cooperation which is mutually beneficial. Theories of moral judgment should not obscure this fundamental distinction.

Our recent review demonstrates that “purity” is a messy construct with at least nine popular scientific understandings. Cultural beliefs about self-control help unify some of these understandings, but much messiness remains. The harm-centric theory of dyadic morality suggests that purity violations can be comprehensively understood as abstract harms, acts perceived by some people (and not others) to indirectly cause suffering.

We argue that people may resist temptations not only with the aim of acquiring more self-control, but also because they want to convince others that they are patient and already possess self-control.

Recent findings in evolutionary psychology explain how moral disciplining is connected to the need for collective action. Morals are strict in societies affected by war or perceived collective danger, but loose where peace and security prevail. This theory supplements the moral disciplining theory by providing an evolutionary explanation for the postulated link between puritanism and the need for cooperation.

We argue that the occurrence of puritanical norms cannot simply be explained by appealing to the need for cooperation. Anthropological and archaeological studies suggest that across history and cultures’ self-indulgent behaviours, such as excessive drinking, eating, and feasting, have been used to enhance cooperation by enforcing social and group identities.

We agree with Fitouchi et al. that self-denial is sometimes moralized to signal capacity for cooperation, but propose that a person's cooperative character is more precisely judged by willingness to follow cultural, group, and interpersonal goals, for which many rules can serve as proxies, including rules about abstention. But asceticism is not a moral signal if its aims are destructive, while indulging impulses in a culturally approved way can also signal cooperation.

This account of puritanical morality is useful and innovative, but makes two errors. First, it mischaracterizes the purity foundation as being unrelated to cooperation. Second, it makes the leap from cooperation (broadly construed) to a monist account of moral cognition (as harm or fairness). We show how this leap is both conceptually incoherent and inconsistent with empirical evidence about self-control moralization.

Purity violations overlap with other moral domains. They are not uniquely characterized by hypothesized markers of purity – the witness's emotion of disgust, taint to perpetrator's soul, or the diminished role of intention in moral judgment. Thus, Fitouchi et al.'s proposition that puritanical morality (a subset of violations in the purity domain) is part of cooperation-based morality is an important advance.

As the cultural evolution of a puritanical moral norm in Turkey illustrates, puritanical moral norms are not developed by nonrational reasoning concerned with purity and cleanliness. People use puritanical moral rules as moral heuristics for making intendedly rational decisions about whether to cooperate or not when the commitment of the counterparty is uncertain.

Why do people moralize harmless behaviors? Although people rely on cooperative principles in making their moral judgments, I argue that self-interest likely plays a role even in these judgments. I suggest potential lines of research that might examine the role of self-interest in puritanical morality.

Fitouchi et al. claim that seemingly victimless pleasures and nonproductive activities are moralized because they alter self-control. Their account predicts that: (1) victimless excesses are negatively moralized because they diminish self-control, and (2) restrained behaviors are positively moralized because they enhance self-control. Several examples run contrary to these predictions and call into question the general relationship between self-control and cooperation.

Some aspects of moral disciplining theory (MDT) – the association between cooperation and self-control; the notion that people and societies value sacrifice and costly prosocial behaviors – are well supported. However, other aspects of MDT – the association between religion/religiosity and cooperation; the notion that sacrifice and costly prosocial behaviors are no longer valued in “western, educated, industrialized, rich, and democratic” (WEIRD) societies – are inconsistent with existing evidence.

Because suppression of sex has been and is at the core of puritanical morals, a proper account thereof would need to explain why suppression of sex has been largely directed towards the human female. Not only do the authors not account for this pattern, but their general model would seem to predict the reverse – that is, greater suppression/control of the male libido.

I propose that young children may be a useful test case for Fitouchi et al.'s theory that certain seemingly harmless acts are moralized because they are seen as risk factors for future poor cooperation. The theory predicts that prior to the development of certain folk-psychological beliefs about self-control, children should be untroubled by violations of puritanical morality, and that an adult-like folk psychology of self-control should develop in tandem with disapproval of such violations.

This commentary raises three points in response to the target article. First, what appear to be victimless behaviors in highly individualistic, post-industrial societies might have a direct impact on group members in small-scale societies. Second, many societies show marked tolerance or ambivalence toward intemperate behavior. Third, undisciplined behavior is not antithetical to cooperation but can be used to cooperative ends.

Puritanical morality regulates a range of seemingly insignificant behaviors, including those involving human sexuality. A sizable portion of the latter particularly burdens women, who are held responsible for the moral conduct of men. In my paper, I show that these norms have not necessarily served to evolve cooperation, but to subjugate and eliminate women from public life.

Contradicting our earlier claims of American moral exceptionalism, recent self-replication evidence from our laboratory indicates that implicit puritanism characterizes the judgments of people across cultures. Implicit cultural evolution may lag behind explicit change, such that differences between traditional and non-traditional cultures are greater at a deliberative than an intuitive level. Not too deep down, perhaps we are all implicit puritans.

Fitouchi et al. persuasively argue against popular disgust-based accounts of puritanical morality. However, they do not consider alternative account of moral condemnation that is also based on the psychology of disgust. We argue that these other disgust-based accounts are more promising than those dismissed in the target article.

There is a puzzle in reconciling the widespread presence of puritanical norms condemning harmless pleasures with the theory that morality evolved to reap the benefits of cooperation. Here, we draw on the work of several philosophers to support the argument by Fitouchi et al. that these norms evolved to facilitate and scaffold self-control for the sake of cooperation.

Fitouchi et al.'s moral disciplining approach highlights the significant role social evaluations of self-control appear to play in human moral judgment. At the same time, attributing the wide range of puritanical concerns to a singular focus on self-control seems unwarranted. A more pluralistic approach would enrich understanding of moral judgment in all its cultural and historical diversity.