Purity is a popular topic in moral psychology. One popular theory argues that purity represents a unique moral “foundation” – a distinct domain of moral judgment – that explains why liberals and conservatives disagree about politics (Graham, Haidt, & Nosek, Reference Graham, Haidt and Nosek2009; Haidt, Reference Haidt2007). This theory suggests conservatives but not liberals care about violations of purity, clarifying why conservatives are more likely to condemn gay marriage and burning Bibles. The problem with this argument is that purity is not a distinct domain (Schein & Gray, Reference Schein and Gray2015) or unique to conservatives (Frimer, Tell, & Haidt, Reference Frimer, Tell and Haidt2015), and – most challenging – nobody even knows what exactly purity is (Gray, DiMaggio, Schein, & Kachanoff, Reference Gray, DiMaggio, Schein and Kachanoff2022a).

In our recent review, we discovered that there are at least nine popular understandings of purity violations, ranging from disrespecting God to touching feces (Gray et al., Reference Gray, DiMaggio, Schein and Kachanoff2022a). Purity is not defined as a single thing, but a grab-bag of norm-violating acts. We empirically demonstrated that purity is an especially messy concept that is more poorly defined and operationalized than other concepts in morality like harm or loyalty (DiMaggio, Kachanoff, & Gray, Reference DiMaggio, Kachanoff and Gray2022), and without a clear definition of purity, it is incomprehensible as a distinct moral domain.

Fitouchi et al. tackle the messiness of purity, moving away from the unsupported ideas of distinct moral foundations. They identify a “constellation of moral norms” in puritanical cultures that emphasize self-control and temperance. Rather than arguing purity concerns are some cognitive fault-line separating modern American republicans and democrats, the authors explain that many purity norms emerge from the application of puritanical religious beliefs about intuitions around cooperation. Fitouchi et al. identify that people have the intuition that engaging in impure acts (e.g., bodily pleasures) hampers self-control capacities, and self-control is essential to being a cooperative member of society. Therefore, if someone revels in bizarre sexual fetishes, they won't work well in teams, pay back favors, or respect property rights.

This self-control account helps unify some of the acts labeled as “impure” but not all of them. Other purity concerns, like norms around not engaging in disgusting acts (Haidt, Reference Haidt2007) and the culturally situated prohibitions of eating meat following the death of a loved one in Hindu religious communities (Shweder, Much, Mahapatra, & Park, Reference Shweder, Much, Mahapatra, Park, Brandt and Rozin1997), are still moralized, but this isn't because rolling in urine or eating chicken makes you less likely to pay back loans. A full account of purity must also be able to explain moral judgments like these – we need a meta-theory of purity.

We argue instead that the moralization of all the different purity concerns can be better explained by understanding their relationship to perceptions of harm. The theory of dyadic morality (TDM) argues that we all share a harm-based moral mind and that we condemn moral acts based on how harmful they seem (Schein & Gray, Reference Schein and Gray2018). Further research supports the central role of harm in predicting moral condemnation across various “moral domains” (Ochoa, Reference Ochoa2022) (Fig. 1).

Figure 1. Perceptions of harm predict moral judgment across diverse acts. Data from Ochoa (Reference Ochoa2022).

However, harm is a matter of perception and can vary based on assumptions of the perceiver. The wrongness of purity violations are debated between people, not because they appeal to any distinct moral mechanisms, but because their harmfulness is very ambiguous. We might all agree that child abuse causes harm to a vulnerable person, but the acts used to operationalize purity are generally seen to lack obvious interpersonal harm (Gray et al., Reference Gray, DiMaggio, Schein and Kachanoff2022a). Rolling around in sterile urine is weird but doesn't cause immediate injury. Where's the harm there? Research suggests that people do perceive some harm – and concrete victims – in these disgusting acts (Gray, Schein, & Ward, Reference Gray, Schein and Ward2014; Gray et al., Reference Gray, MacCormack, Henry, Banks, Schein, Armstrong-Carter and Muscatell2022b), and we build off these findings to suggest an overarching and culturally situated view of purity (Gray et al., Reference Gray, DiMaggio, Schein and Kachanoff2022a). Real-world purity judgments revolve around abstract harms, moral norms perceived by some people (and not others) to indirectly cause suffering. These abstract harms often do not have an objective direct victim but instead have a perceived indirect victim.

The abstract harms account of purity was clearly supported when purity was first introduced to psychology by Richard Shweder as a form of moral rhetoric. Shweder and colleagues (Reference Shweder, Much, Mahapatra, Park, Brandt and Rozin1997) studied how the Oriya Hindu Brahmin community discussed purity concerns around “death pollution.” These Brahmins believe that one must eat a special diet to process the death pollution of a dead person. However, they also believe that failure to do so harms the soul of the deceased by delaying their reincarnation (Shweder, Reference Shweder and Fassin2012). Although American researchers may not directly see suffering caused by some actions, those who follow these purity norms believe it causes harm downstream.

Other abstract harms rely on more metaethical beliefs, like “what if everyone did it?!” Levine, Kleiman-Weiner, Schulz, Tenenbaum, and Cushman (Reference Levine, Kleiman-Weiner, Schulz, Tenenbaum and Cushman2020) clarify how this logic of universalization influences harm perceptions through the case of overfishing. Although it isn't necessarily harmful for a single person to fish as much as humanly possible, if everyone acted this way, ocean ecosystems would collapse, so the best moral norm is to exercise moderation. Fitouchi et al.'s description of puritanical morals implies this logic in puritan prohibitions against drugs and weird sex acts based on the belief that this leads you to be a less cooperative individual. Although one onanist may not bring about civilizational collapse, puritans believe that the most vulnerable in our society would be harmed if we were all out-of-control sodomites who “did not aid the poor and needy” (Ezekiel, 16:49).

Fitouchi et al. suggest a method for how psychologists might be able to better incorporate cultural beliefs into our investigations of morality. By analyzing how particular beliefs scaffold onto harm, the authors provide a rich account of how unique moral norms emerge from specific social contexts. Rather than accepting that some moral divides represent immutable group differences in the mind, this approach suggests that we can foster moral understanding by learning about beliefs which drive others' perceptions of abstract harm, and moral psychologists can use this method to continue to unravel the problem of purity.