Purity is not a distinct moral domain.

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.