Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
J Evol Biol. 2009 Nov;22(11):2192-200. doi: 10.1111/j.1420-9101.2009.01835.x. Epub 2009 Sep 3.
Conflict and cooperation for the exploitation of public goods are usually modelled as an N-person prisoner's dilemma. Many social dilemmas, however, would be described more properly as a volunteer's dilemma, in which a certain number of individuals are necessary to produce a public good. If volunteering is costly, but so is failure to produce the public good, cheaters can invade and form a stable mixed equilibrium with cooperators. The dilemma is that the benefit for the group decreases with group size because the larger the group is, the less likely it is that someone volunteers. This problem persists even in the presence of a high degree of relatedness between group members. This model provides precise, testable predictions for the stability of cooperation. It also suggests a counterintuitive but practical solution for this kind of social dilemmas: increasing the damage resulting from the failure to produce the public good increases the probability that the public good is actually produced. Adopting a strategy that entails a deliberate risk (brinkmanship), therefore, can lead to a benefit for the society without being detrimental for the individual.
对于公共物品的开发，冲突与合作通常被建模为 N 人囚徒困境。然而，许多社会困境如果用志愿者困境来描述更为恰当，在这种困境中，需要一定数量的个体来产生公共物品。如果做志愿者是有代价的，而不生产公共物品也是有代价的，那么骗子就可以入侵并与合作者形成一个稳定的混合均衡。困境在于，随着群体规模的扩大，群体的利益会减少，因为群体越大，志愿者出现的可能性就越小。即使在群体成员之间存在高度相关性的情况下，这个问题仍然存在。这个模型为合作的稳定性提供了精确的、可测试的预测。它还为这种社会困境提供了一个反直觉但实用的解决方案：增加不生产公共物品所造成的损失会增加公共物品实际生产的可能性。因此，采取一种故意冒险（边缘政策）的策略，不仅对个人没有损害，还可以为社会带来好处。
