我们为何偏好公平：一个演化视角的解释

Why Do We Prefer Fairness:An Explanation Based on Evolutionary View

当代行为经济学已经确认人类存在公平心理偏好,但并未回答它从何而来。本文提出一个演化解释:人类公平偏好的根源可能在于人类早期的进化过程。通过一个演化博弈模型和随机演化仿真模型表明:(1)在一个完全封闭的族群中,公平偏好的单态社会是随机稳定的演化均衡,非公平偏好的双态社会也是演化稳定的但并非随机稳定的;(2)若同时考虑族群之间的竞争,则公平偏好的单态社会将是唯一的演化稳定均衡。其原因在于,合作机会多少与合作利益大小是此消彼长的,公平行为最能够平衡合作机会与合作利益对生存竞争的影响,从而成为个体—族群两个层面的生存竞争中最具适存性优势的行为模式。人类的公平偏好,可能源于本能性的公平行为在人类早期进化中的适存性优势。

Cotemporary behavioral economics make it convinced that human being has fairness preference, but do not reveal why it exists. This paper develops an evolutionary explanation to it that fairness preference of human being origins from the process of earlier human being evolution. Based on an evolutionary game model and a stochastic evolution simulation model, this paper shows that, a） in a closed group, singular state society with fairness preference is stochastic evolutionary stable equilibrium, while dual-state society with non-fairness preference is also evolutionary stable but not stochastic stable; b） if the competitions among groups are considered, the only evolutionary stable equilibrium is the singular state society with fairness preference. The reasons are as follows, there is a tradeoff between cooperation opportunities and the cooperation benefit and fair behavior can balance the effects of cooperation opportunity and cooperation benefit on survival competition, and then becomes the behavioral paradigm with optimal fitness in survival competition at both individual and group level.