Faculty of Information Technology, Monash University, Melbourne, Australia.
Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, 24306 Plön, Germany.
J R Soc Interface. 2019 Jul 26;16(156):20190127. doi: 10.1098/rsif.2019.0127. Epub 2019 Jul 24.
The emergence and maintenance of punishment to protect the commons remains an open puzzle in social and biological sciences. Even in societies where pro-social punishing is common, some individuals seek to cheat the system if they see a chance to do so-and public goods are often maintained in spite of cheaters who do not contribute. We present a model accounting for all possible strategies in a public goods game with punishment. While most models of punishment restrict the set of possible behaviours, excluding seemingly paradoxical anti-social strategies from the start, we show that these strategies can play an important role in explaining large-scale cooperation as observed in human societies. We find that coordinated punishment can emerge from individual interactions, but the stability of the associated institutions is limited owing to anti-social and opportunistic behaviour. In particular, coordinated anti-social punishment can undermine cooperation if individuals cannot condition their behaviour on the existence of institutions that punish. Only when we allow for observability and conditional behaviours do anti-social strategies no longer threaten cooperation. This is due to a stable coexistence of a minority supporting pro-social institutions and those who only cooperate if such institutions are in place. This minority of supporters is enough to guarantee substantial cooperation under a wide range of conditions. Our findings resonate with the empirical observation that public goods are resilient to opportunistic cheaters in large groups of unrelated individuals. They also highlight the importance of letting evolution, and not modellers, decide which strategies matter.
在社会和生物科学中，保护公共资源的惩罚的出现和维持仍然是一个未解之谜。即使在亲社会惩罚很常见的社会中，如果某些人有机会作弊，他们也会试图欺骗系统——尽管有不贡献的作弊者，公共物品通常仍能得到维持。我们提出了一个在具有惩罚的公共物品博弈中考虑所有可能策略的模型。虽然大多数惩罚模型限制了可能行为的集合，从一开始就排除了看似矛盾的反社会策略，但我们表明，这些策略可以在解释人类社会中观察到的大规模合作方面发挥重要作用。我们发现，协调的惩罚可以从个体互动中出现，但由于反社会和机会主义行为，相关制度的稳定性是有限的。特别是，如果个体不能根据惩罚机构的存在来调节自己的行为，协调的反社会惩罚可能会破坏合作。只有当我们允许可观察性和条件行为时，反社会策略才不会再次威胁合作。这是由于少数支持亲社会制度的人以及只有在这些制度存在的情况下才合作的人之间的稳定共存。我们的发现与这样一种实证观察相呼应，即在没有关联的大群体中，公共物品对机会主义的作弊者具有弹性。它们还强调了让进化而不是建模者来决定哪些策略重要的重要性。
