How “punishing evil and promoting good” promotes cooperation in social dilemma

In this paper, based on the social dilemma model, we introduce the punishing evil and promoting good strategy, whose basic strategy is to cooperate, while to obtain benefits at the cost of payment. Specifically, when the person who punishes evil and promotes good plays a game with the cooperator, his contributions will bring the same benefits to both parties, reflecting the promoting good. However, when the person who punishes evil and promotes good plays a game with the defector, making the benefit of the defector loss and become his own benefit, reflecting the punishing evil. The results show that when only the role of punishing evil is considered, increasing punishment strength can easily make those punishing evil and promoting good and ordinary cooperators appear. But only increasing the punishment is not enough to weed out the defectors. When only the effect of promoting good is considered, under a smaller temptation to defection, the increase of the reward strength can transform the system from a full defection state to a full cooperation state. Whereas when the temptation is greater, the increase in the reward is not enough for the cooperator to survive and only defectors exist in the system at this time. In addition, there exist combinations of minimum values of punishment and reward that bring the system to a defector-free state. In conclusion, our study finds effective intervals for promoting the development of those who punish evil and promote good and ordinary cooperators, respectively.