Elsevier

Evolution and Human Behavior

Volume 41, Issue 5, September 2020, Pages 415-429
Evolution and Human Behavior

Kinship intensity and the use of mental states in moral judgment across societies

https://doi.org/10.1016/j.evolhumbehav.2020.07.002Get rights and content

Abstract

Decades of research conducted in Western, Educated, Industrialized, Rich, & Democratic (WEIRD) societies have led many scholars to conclude that the use of mental states in moral judgment is a human cognitive universal, perhaps an adaptive strategy for selecting optimal social partners from a large pool of candidates. However, recent work from a more diverse array of societies suggests there may be important variation in how much people rely on mental states, with people in some societies judging accidental harms just as harshly as intentional ones. To explain this variation, we develop and test a novel cultural evolutionary theory proposing that the intensity of kin-based institutions will favor less attention to mental states when judging moral violations. First, to better illuminate the historical distribution of the use of intentions in moral judgment, we code and analyze anthropological observations from the Human Area Relations Files. This analysis shows that notions of strict liability—wherein the role for mental states is reduced—were common across diverse societies around the globe. Then, by expanding an existing vignette-based experimental dataset containing observations from 321 people in a diverse sample of 10 societies, we show that the intensity of a society's kin-based institutions can explain a substantial portion of the population-level variation in people's reliance on intentions in three different kinds of moral judgments. Together, these lines of evidence suggest that people's use of mental states has coevolved culturally to fit their local kin-based institutions. We suggest that although reliance on mental states has likely been a feature of moral judgment in human communities over historical and evolutionary time, the relational fluidity and weak kin ties of today's WEIRD societies position these populations' psychology at the extreme end of the global and historical spectrum.

Introduction

For many readers, the above epigraph portrays a curious and almost counter-intuitive approach to moral judgment. Whether a death comes about through an intentional act of murder or is entirely accidental, the punishment is similarly harsh. This narrow focus on outcomes at the exclusion of intent contrasts with conceptions of culpability and responsibility common in many Western, industrialized societies today. The approach to guilt that many readers are familiar with, which began to develop in Western law during the Middle Ages, focuses primarily on inferences about the mental states of those involved (Berman, 1983; Harper, 2013; Henrich, 2020).

In recent decades, research on moral judgment among populations that are Western, Educated, Industrialized, Rich, and Democratic (WEIRD) has documented subjects' consistent tendency to heavily weight agents' mental states, and particularly their intentions, when assessing the moral permissibility and punishment-worthiness of actions. For example, WEIRD subjects judge attempted harms, which involve malicious intent but a neutral outcome, more harshly than accidental harms, which involve innocent intent but a negative outcome (Young, Cushman, Hauser, & Saxe, 2007; Young and Saxe, 2008, Young and Saxe, 2009). Although intent-based moral judgment has a complex developmental trajectory (Cushman, Sheketoff, Wharton, & Carey, 2013), some evidence indicates that even babies incorporate information about intent into their social decisions: given the choice, preverbal infants prefer a puppet who tried but failed to help a third party over a puppet who tried but failed to hinder a third party (Hamlin, 2013). These broad and replicable patterns (Cushman, 2015; Saxe, 2016; Young & Tsoi, 2013) suggest that the great importance of mental states in making moral judgments may be a reliably developing feature of human cognition that emerges with little input from cultural evolution. Considering others' mental states may serve as an adaptive strategy that helps individuals (1) pick the best cooperative partners, (2) avoid uncooperative or dangerous individuals (Chakroff et al., 2016; Young & Tsoi, 2013; Young & Waytz, 2013), (3) select and accurately learn from moral exemplars, or (4) punish and teach most effectively.

However, several recent studies reveal broad variation across societies in the manner and context in which people use mental states during moral judgment. In the largest cross-cultural study to date, Barrett et al. (2016) compared responses to moral-judgment vignettes featuring physical harm, poisoning, theft, and food taboo violations across ten societies. While participants from Los Angeles and rural Ukraine placed substantial weight on intentions in their judgments, pastoralists from Namibia and fisher-horticulturalists from Fiji deemed high- and low-intent harms across most domains to be equally bad, punishment-worthy, and reputation-damaging. Participants from the remaining six societies fell in between these extremes. Barrett et al. (2016) also found substantial variation in the degree to which potentially mitigating factors like self-defense, insanity, and necessity altered the severity of moral judgments. Because taking a mitigating factor into account often requires consideration of a perpetrator's state of mind, this result further indicates population-level variation in the tendency to employ mental-state reasoning during moral judgment. Replicating the noteworthy patterns found in Fiji, McNamara, Willard, Norenzayan, and Henrich (2019) confirmed that indigenous Fijians place more focus on outcomes than intentions when judging moral scenarios, while still taking intentions into account to some degree, in certain situations (e.g. deeming attempted harms, which involve negative intent but neutral outcome, somewhat “bad”). Related patterns have also been detected in industrialized Asian societies. In contemporary Japan, participants weigh intentions less heavily than in the U.S. when making moral judgments, particularly in certain contexts (Hamilton & Sanders, 1992). Together, these results suggest that while some inclination to consider intentions during moral judgment in at least some situations has been found in all societies studied to date, WEIRD people, with their laser-like focus on mental states, seem to lie at the extreme end of the global distribution.

This curious pattern presents a puzzle: how can we explain the observed cross-cultural variation? Here, we develop and test a cultural evolutionary theory to answer this question, arguing that a substantial part of this variation can be explained by the strength of kin-based institutions, or kinship intensity.

We first lay out a theoretical framework to support the hypothesis that reliance on mental states during moral judgments should decrease with kinship intensity. Then, to set the scene for our analysis of cross-cultural experimental data (Barrett et al., 2016), we review the ethnographic evidence for norms that might suppress the use of mental states, specifically focusing on opacity of mind and strict liability. Contrary to WEIRD intuitions, such mental-state-disregarding norms are widespread. This suggests that, rather than highlighting a few peculiar societies, recent cross-cultural studies of the importance of mental states in moral judgment may be uncovering globally and historically important forms of psychological variation. Next, we provide empirical support for our hypothesis, showing that kinship intensity predicts the use of mental states during moral judgment across a diverse sample of ten societies. In closing, we suggest that although mentalizing has likely been a feature of moral judgment in many communities, the relational fluidity and weak social ties of today's WEIRD societies place this population's psychology at the extreme end of the global and historical spectrum.

Section snippets

Theoretical framework

Theory of mind, or the ability to infer others' beliefs, thoughts, goals, and desires, is likely a reliably developing feature of human psychology (Barrett, 2015; Barrett et al., 2013; Henrich, 2016). This does not mean, however, that people everywhere employ theory of mind in the same contexts or with the same frequency; rather, social norms and other cultural technologies may shape, sharpen, and direct its use. Institutions, or packages of culturally-transmitted social norms, exert a potent

Mental states in moral judgment in the ethnographic record

In the global and historical spectrum, just how prevalent is the tendency to deemphasize mental states during moral judgment? Recent studies have begun to document cross-cultural variation in this tendency (Barrett et al., 2016; McNamara, 2016; McNamara et al., 2019). However, despite careful design and implementation, some researchers may worry that these results reflect participants' misunderstanding or some other experimental issue. To assuage these fears, we show that norms and institutions

Kinship intensity and reliance on mental states in moral judgments

We expanded an existing dataset from Barrett et al. (2016), who investigated moral judgments using vignettes in a diverse sample of ten societies that varied across subsistence mode, geography, ecology, and language (Fig. 3, Table S4). In this study, 322 participants rated the badness, punishment-worthiness, and reputation-damaging effects of different harm scenarios in two studies. In the first, the Intention vignettes featured either high-intent harm (e.g. an agent stealing someone's bag) or

General discussion

We have argued that some of the variation in the use of mental states in moral judgment can be explained as a psychological calibration to the social incentives, informational constraints, and cognitive demands of kin-based institutions, which we have assessed using our construct of kinship intensity. Our examination of ethnographic accounts of norms that diminish the importance of mental states reveals that these are likely common across the ethnographic record, while our analysis of data on

Data availability

The data associated with this research are available at: https://osf.io/65krf/?view_only=0ee63a2f9c6541c3b3ab4c4fe2663a13.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of Competing Interest

We declare no conflicts of interest.

Acknowledgements

We thank Anke Becker, Thomas Flint, and Tiffany Hwang for their help coding the Kinship Survey and the ethnographic review, and Steven Worthington of Harvard’s Institute for Quantitative Social Science for his statistical guidance. We also thank the communities, participants, and research assistants who made the Barrett et al. (2016) study possible.

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