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Tuesday, January 17, 2023

Deeply Rational Reasons for Irrational Beliefs

Barlev, M., & Neuberg, S. L. (2022, December 7).


Why do people hold irrational beliefs? Two accounts predominate. The first spotlights the information ecosystem and how people process this information; this account either casts those who hold irrational beliefs as cognitively deficient or focuses on the reasoning and decision-making heuristics all people use. The second account spotlights an inwardly-oriented and proximate motivation people have to enhance how they think and feel about themselves. Here, we advance a complementary, outwardly-oriented, and more ultimate account—that people often hold irrational beliefs for evolutionarily rational reasons. Under this view, irrational beliefs may serve as rare and valued information with which to rise in prestige, as signals of group commitment and loyalty tests, as ammunition with which to derogate rivals in the eyes of third-parties, or as outrages with which to mobilize the group toward shared goals. Thus, although many beliefs may be epistemically irrational, they may also be evolutionarily rational from the perspective of the functions they are adapted to serve. We discuss the implications of this view for puzzling theoretical phenomena and for changing problematic irrational beliefs.


Why do we hold irrational beliefs that often are not only improbable, but impossible? According to some, the information ecosystem is to blame, paired with deficiencies in how people process information or with heuristic modes of processing. According to others, it is because certain beliefs—regardless of their veracity—can enhance how we think and feel about ourselves. We suggest that such accounts are promising but incomplete: many irrational beliefs exist because they serve crucial interpersonal (and more ultimate rather than proximal) functions.

We have argued that many irrational beliefs are generated, entertained, and propagated by psychological mechanisms specialized for rising in prestige, signaling group commitment and testing group loyalty, derogating disliked competitors in the eyes of third-parties, or spreading common knowledge and coordination toward shared goals. Thus, although many beliefs are epistemically irrational, they can be evolutionarily rational from the perspective of the functions they are adapted to serve.

Is it not costly to individuals to hold epistemically irrational beliefs? Sometimes. Jehovah's Witnesses reject life-saving blood transfusions, a belief most consider to be very costly, explaining why courts sometimes compel blood transfusions such as in the case of children. Yet even here, the benefits to individuals of carrying such costly beliefs may outweigh their costs, at least for some. For example, if such belief are designed to signal group commitment, they might emerge among particularly devout members of groups or among groups in which the need to signal commitment is particularly strong; the costlier the belief, the more honest a signal of group commitment it is (Petersen et al., 2021). However, such cases are the exception—most of the irrational beliefs people hold tend to be inferentially isolated and behaviorally inert. For example, the belief that God the Father, the Son, and the Holy Spirit are one may function for a Christian as a signal of group affiliation and commitment, without carrying for the individual many costly inferences or behavioral implications (Petersen et al., 2021; Mercier, 2020).