A pluralist theory is one which entails that there are multiple, incommensurable kinds of moral concern; for example, both purity and harm. By contrast, a monist theory is one which identifies one fundamental aspects, most likely harm, or something related to harm, as the sole basis for all genuinely moral concern.
What kind of evidence might favour pluralism over monism? This section introduces two key sources.
Second,specific kinds of moral concern (e.g. purity) appear to have had different roles in evolution. For instance, van Leeuwen, Park, Koenig, & Graham (2012) had subjects answer questions which indicated the degree to which they endorsed moral concerns linked to purity, authority and loyalty (the ‘binding foundations’) compared to the degree to which they endorsed moral foundations linked to harm and unfairness (the ‘individual foundations’). They found a link between stronger endorsement of binding foundations and the historical prevalence of pathogens in the region subjects lived:
‘historical pathogen prevalence—even when controlling for individual-level variation in political orientation, gender, education, and age—significantly predicted endorsement of Ingroup/loyalty [stats removed], Authority/respect, and Purity/sanctity; it did not predict endorsement of Harm/care or Fairness/reciprocity’ (van Leeuwen et al., 2012).
This is coherent with the idea that purity has been important because it enabled humans to mitigate risks from pathogens associated with their diet long before they understood pathogens.
While none of these reasons are decisive, it appears that moral pluralism is needed for a variety of explanations. This justifies us in accepting that there are incommensurable kinds of moral concern.
binding foundations : Categories of moral concern linked to social needs; these are often taken to be betrayal/loyalty, subversion/authority, and impurity/purity (Graham et al., 2011).
individual foundations : Categories of moral concern linked to individual needs; these are often taken to be harm/care, cheating/fairness (Graham et al., 2011). Sometimes called individualizing foundations.
moral disengagement : Moral disengagement occurs when self-sanctions are disengaged from inhumane conduct. Bandura (2002, p. 103) identifies several mechanisms of moral disengagement: ‘The disengagement may centre on redefining harmful conduct as honourable by moral justification, exonerating social comparison and sanitising language. It may focus on agency of action so that perpetrators can minimise their role in causing harm by diffusion and displacement of responsibility. It may involve minimising or distorting the harm that follows from detrimental actions; and the disengagement may include dehumanising and blaming the victims of the maltreatment.’
Barnett, M. D., Öz, H. C. M., & Marsden, A. D. (2018). Economic and Social Political Ideology and Homophobia: The Mediating Role of Binding and Individualizing Moral Foundations. Archives of Sexual Behavior, 47(4), 1183–1194. https://doi.org/10.1007/s10508-017-0989-2
Chakroff, A., Russell, P. S., Piazza, J., & Young, L. (2017). From impure to harmful: Asymmetric expectations about immoral agents. Journal of Experimental Social Psychology, 69, 201–209. https://doi.org/10.1016/j.jesp.2016.08.001
Dungan, J. A., Chakroff, A., & Young, L. (2017). The relevance of moral norms in distinct relational contexts: Purity versus harm norms regulate self-directed actions. PLOS ONE, 12(3), e0173405. https://doi.org/10.1371/journal.pone.0173405
Graham, J., Haidt, J., Koleva, S., Motyl, M., Iyer, R., Wojcik, S. P., & Ditto, P. H. (2013). Moral Foundations Theory: The Pragmatic Validity of Moral Pluralism. In P. Devine & A. Plant (Eds.), Advances in Experimental Social Psychology (Vol. 47, pp. 55–130). Academic Press. https://doi.org/10.1016/B978-0-12-407236-7.00002-4
Graham, J., Haidt, J., Motyl, M., Meindl, P., Iskiwitch, C., & Mooijman, M. (2019). Moral Foundations Theory: On the advantages of moral pluralism over moral monism. In K. Gray & J. Graham (Eds.), Atlas of Moral Psychology. New York: Guilford Publications.
Graham, J., Haidt, J., & Nosek, B. A. (2009). Liberals and conservatives rely on different sets of moral foundations. Journal of Personality and Social Psychology, 96(5), 1029–1046. https://doi.org/10.1037/a0015141
Graham, J., Nosek, B. A., Haidt, J., Iyer, R., Koleva, S., & Ditto, P. H. (2011). Mapping the moral domain. Journal of Personality and Social Psychology, 101(2), 366–385. https://doi.org/10.1037/a0021847
Hendel, R. S. (1987). Of Demigods and the Deluge: Toward an Interpretation of Genesis 6:1-4. Journal of Biblical Literature, 106(1), 13–26. https://doi.org/10.2307/3260551
Koleva, S. P., Graham, J., Iyer, R., Ditto, P. H., & Haidt, J. (2012). Tracing the threads: How five moral concerns (especially Purity) help explain culture war attitudes. Journal of Research in Personality, 46(2), 184–194. https://doi.org/10.1016/j.jrp.2012.01.006
van Leeuwen, F., Park, J. H., Koenig, B. L., & Graham, J. (2012). Regional variation in pathogen prevalence predicts endorsement of group-focused moral concerns. Evolution and Human Behavior, 33(5), 429–437. https://doi.org/10.1016/j.evolhumbehav.2011.12.005