Cleansing effects are widely replicated in embodied social cognition research. Lee and Schwarz propose that these effects could be interpreted as a proxy of more basic procedures of separation, in line with Semin and Smith's (Reference Semin and Smith2008) view on embodied grounding, which suggests that psychological processes could be rooted in motoric and physical actions.

In this commentary, we would like to propose that the practice of psychological separation is embedded in human social activities that are created in historical realities. Acknowledging the primacy of action in attitudinal and cognitive processes (Harmon-Jones, Harmon-Jones, & Levy, Reference Harmon-Jones, Harmon-Jones and Levy2015), we perceive evaluations and cognitions as means in organized social practices that were developed in historical realms. The evaluation of basic social practices, such as separation, is determined by what is valued in the given socio-cultural context. In this commentary, we would like to interpret human actions of separation and cleansing as a consequence of agricultural practices and intergroup relations developed in modern societies.

Modern modes of agriculture have been developed with a goal of increasing effectiveness in pest management and weed control. They involved plant and animal selection, crop rotations, crop sanitation, and the use of agrochemicals. All these practices could be seen as acts of separation and cleansing. The prevalence of this approach in agriculture was accompanied by tendencies in Western societies to value separation and cleansing also in other life domains.

In their most extreme forms, these processes are reflected in segregationist social ideas, ideologies, and developments such as hygienism, eugenics, ethnic cleansing, and genocide. The ideas of crop control and selective breeding of animals were developed in late eighteenth and early nineteenth century Britain, as part of the Second Agricultural Revolution (Mazoyer & Roudart, Reference Mazoyer and Roudart2006; Mingay, Reference Mingay1977), which followed the first revolution involving the elimination of fallowing and mechanization. The trend toward crop and animal selection and farm specialization was drawn by the need of increased productivity of agriculture. This process was based on the development of fertilizer industry. The careful selection of crops and animals and the deepening of farm specialization (which led to separation of grain-producing farms from animal farms) served the goal of ever growing productivity. These innovations in agriculture are considered as being important sources of eugenic and hereditarian ideas, as well as sterilization policies in many countries (Gibbons, Reference Gibbons2014; Kevles, Reference Kevles1995; Kimmelman, Reference Kimmelman1983). From the eugenic standpoint, agriculture and raising children on a farm represented also a crucial factor in supporting the wellbeing of the population (Cook, Reference Cook1916).

The principle of “social gardening” (Bauman, Reference Bauman2000) – a perception of society as an object of designing, cultivating, and weed-poisoning, was apparent in most modern genocides. Metaphors related to cleansing accompanied many mass atrocities that involved radical forms of social separation (e.g., the concept of “Jundenrein” and “Rassenhygiene” in Nazi Germany during the Holocaust; phrases such as “inyezi” and “cutting trees” used in the Rwandan Genocide propaganda, etc.; Bilewicz, Reference Bilewicz and Newman2019). Sanitizing language, involving such terms as “wasting people,” “surgical strikes,” “servicing the target” are used as means of moral disengagement by the perpetrators of mass violence (Bandura, Reference Bandura1999; Reference Bandura2016; McAlister, Bandura, & Owen, Reference McAlister, Bandura and Owen2006). Bandura (Reference Bandura and Christie2012, p. 2) notes that “people behave more cruelly when detrimental practices are sanitized than when they are called aggression.”

The modern approach to agriculture has been questioned in recent decades. Some current trends of more sustainable agriculture emphasize integration rather than segregation. This includes, above all, permaculture, understood, in general as agriculture modeled on natural, “unclean,” ecosystems. Permaculture is realized, among others, by using a variety of inter- and multi-cropping methods or “forest gardens” (Bilewicz, Reference Bilewicz2020; Holmgren, Reference Holmgren2002; Veteto & Lockyer, Reference Veteto and Lockyer2008). Also post-genocide human intergroup relations have gravitated toward desegregation and reconciliation in many societies worldwide – most prominently in the United States and post-apartheid South Africa. Anti-segregationism is the prominent theme of contemporary collective action (e.g., Black Lives Matter movement, Wilson, Reference Wilson2016), as well as the key psychological strategy of conflict resolution and reconciliation (Durrheim & Dixon, Reference Durrheim and Dixon2005). Nuanced narratives and desegregated collective memories form and important aspect of post-genocide reconciliation, where atypical moral exemplars are used (Čehajić-Clancy, Reference Čehajić-Clancy2019; Čehajić-Clancy & Bilewicz, Reference Čehajić-Clancy and Bilewicz2020; Witkowska, Beneda, Čehajić-Clancy, & Bilewicz, Reference Witkowska, Beneda, Čehajić-Clancy and Bilewicz2019). Such narratives focus on individuals who acted morally in times of genocide and transgressed intergroup boundaries (e.g., Oskar Schindler or Chiune Sugihara in times of the Holocaust), offering a desegregationist account in collective memories after mass atrocities.

These visible symptoms of changes occurring in contemporary culture suggest that the general value of segregation is decreasing in today's world. It is visible also in the meta-analytic effects of studies looking at immorality-cleansing effects (Lee & Schwarz, Reference Lee and Schwarz2018; Siev, Zuckerman, & Siev, Reference Siev, Zuckerman and Siev2018) showing that the cleansing effects are systematically decreasing in time. It could be seen both in case of the effects of post-decisional dissonance after physical cleansing (Lee & Schwarz, Reference Lee and Schwarz2018; suppl.) as well as in the case of “Macbeth effect,” the relation between immorality and cleansing (Siev et al., Reference Siev, Zuckerman and Siev2018), where more recent studies show smaller effects than the early studies. Although relatively short time since first studies of these phenomena does not allow to draw far-reaching conclusions from this process, it is possible that we are witnessing a significant cultural change that might affect this basic metaphor in human cognition.

To summarize, in this commentary we propose that the metaphor of cleansing was a by-product of modernization processes in human culture and agriculture. Lee and Schwarz suggest that the effects of cleansing are valence- and domain-general, as they are grounded in basic motoric action of segregation. Based on cultural and historical evidence, we claim that the activation of cleansing metaphor triggered positive associations in times when separation was a positively regarded element of human culture and agriculture, but it should not exert the same effect in times when separation became culturally anachronistic. More systematic cross-cultural, meta-analytic, and historical studies would be needed to determine whether such social change could affect basic human metaphors and embodiments.