Abstract
Evolutionary explanations of the co-existence of large-scale cooperation and warfare in human societies rest on the hypothesis of parochial altruism, the view that in-group pro-sociality and out-group anti-sociality have co-evolved. We designed an experiment that allows subjects to freely choose between actions that are purely pro-social, purely anti-social, or a combination of the two. We present behavioral evidence on the existence of strong aggression—a pattern of non-strategic behaviors that are welfare-reducing for all individuals (i.e., victims and perpetrators). We also show how strong aggression serves to dynamically stabilize in-group pro-sociality.
Highlights
“...Ich bin ein Teil von jener Kraft, die stets das Böse will, und stets das Gute schafft” (Faust, 1335–1336). [I am part of that power which eternally wills evil and eternally works good]
An important result by Halevy et al (2008) is that participants to the IPD-MD do not exhibit strong aggression and exert peaceful cooperation when they are allowed to. We hypothesize that this pattern is due to the symmetric design of the IPD-MD that presumably promotes peaceful behaviors: Expectations of retaliation by the other group could potentially inhibit aggressive behaviors. Those expectations play no role in our asymmetric version of the IPD-MD and our results clearly show that participants exhibit patterns of strong aggression in this asymmetric setup
This study provides behavioral evidence consistent with the phenotypic predictions of evolutionary theories of parochial altruism
Summary
“...Ich bin ein Teil von jener Kraft, die stets das Böse will, und stets das Gute schafft” (Faust, 1335–1336). [I am part of that power which eternally wills evil and eternally works good]. The crucial aspect of parochial altruism is the complementarity between in-group pro-sociality and out-group anti-sociality With this respect, our study differs in important ways from earlier work on aggression in the laboratory. An important result by Halevy et al (2008) is that participants to the IPD-MD do not exhibit strong aggression and exert peaceful cooperation when they are allowed to We hypothesize that this pattern is due to the symmetric design of the IPD-MD that presumably promotes peaceful behaviors: Expectations of retaliation by the other group could potentially inhibit aggressive behaviors. By contrast, those expectations play no role in our asymmetric version of the IPD-MD and our results clearly show that participants exhibit patterns of strong aggression in this asymmetric setup. There is a key difference between this experiment and ours: while burning money reduces inequality in Zizzo (2004)’s setting, the corresponding options in our design increased inequality
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