False beliefs which generate group-level benefits

From Why Being Wrong can be Right: Magical Warfare Technologies and the Persistence of False Beliefs by Nathan Nunn and Raul Sanchez de la Sierra. Abstract:

Across human societies, one sees many examples of deeply rooted and widely-held beliefs that are almost certainly untrue. Examples include beliefs about witchcraft, magic, ordeals, and superstitions. Why are such incorrect beliefs so prevalent and how do they persist? We consider this question through an examination of superstitions and magic associated with conflict in the Eastern Democratic Republic of the Congo. Focusing on superstitions related to bulletproofing, we provide theory and case-study evidence showing how these incorrect beliefs persist. Although harmful at the individual-level, we show that they generate Pareto efficient outcomes that have group-level benefits.

From the paper:

Some of those from the villages that stayed to fight were shot and died. But, the cause of their death did not prove the spell to be false. Given the set of conditions that had to be respected, it was obvious that if they died, it must have been because they did not follow some of the conditions. By the time we arrived in the village in March of 2015, the village of Bulambika (and the others in the area) had been freed and had experienced peace for the past two years.

This case provides one example for why false beliefs might persist. The bulletproofing ritual allowed the community to mobilize combatants by altering their beliefs about the likelihood that they would die in combat. While, at the individual level, this false belief is costly – it causes individuals to under-estimate the risk of combat – it nonetheless allowed the community to mobilize against the aggressors, and successfully eradicate them. Thus, although detrimental for some, it was beneficial for the community.

[snip]

In the presence of group-level selection, villages with the false belief of bulletproofing will be more likely to survive, and therefore we would expect this belief to spread throughout the population. Group-level imitation of successful groups would also have the same consequence (Boyd and Richerson, 2002). Thus, in an evolutionary setting where groups compete for survival, such false beliefs increase the average fitness of villages that hold them. Eastern Congo, like many other war-torn parts of the world, has characteristics that make it particularly likely that grouplevel selection is strong (see Henrich, 2004). The groups (i.e., rural villages, lineages, and armed units) are small and homogenous. They also have relatively low levels of migration between the groups. In militia groups, individuals are typically prevented from leaving the group. In rural areas, there is little migration between villages. Most migration is to urban centers. Lastly, because of the high rates of between-group conflict, selection between groups is very strong. With these characteristics, strong group-selection forces can induce false beliefs to spread and persist.

Group level selection is still strongly disputed among biologists, though it does have strong support and some evidence. In addition, anthropology has a long tradition of Just So stories to explain complex phenomena. See Cannibals & Kings by Marvin Harris.

The fact that group selection is still disputed and the fact that the explanations seem like Just So stories does not make the conclusions of Nunn and de la Sierra wrong. It is merely a note of caution. Required, I think, because their proposition is attractively compelling. I especially like their analysis of conditions where false knowledge is more likely to thrive. It is scattered through the paper and some of it is unstated but my reading and inference is that False Beliefs will generally thrive where there is:

Existential threat

Small, homogenous, and self-identified groups

Low levels of out-migration

Low levels of epistemic exposure

High rates of between-group competition

False belief is broadly compatible with existing group norms

False belief is not easily falsifiable

False belief is a catalyst to group level defensive action

That looks like a pretty powerful tool for understanding false knowledge, whether it is east African tribal magic or post-election hysterias in OECD countries (Trump, Brexit, resurgence of nationalists, etc.)