An Evolutionary Approach to Norms

概述

The three most common types of definitions are based upon expectations, values, and behavior.
对于norm的定义有三种，从expectations，values和behavior出发的。

DEFINITION. A norm exists in a given social setting to the extent that individuals usually act in a certain way and are often punished when seen not to be acting in this way.
基于behavior的定义就是惩罚不该做的事情。

To see what rational actors would do in a particular setting, a game theory approach can be used. Game theory assumes the players are fully rational and choose the strategy that gives the highest expected utility over time, given their expectations about what the other players will do.
博弈论假设每个人都是理性的，并且会选择对他们有最大utility的行为，简单地说就是：没有zuo（一声）的人

rationality. Instead, I use an evolutionary approach. This approach is based on the principle that what works well for a player is more likely to be used again while what turns out poorly is more likely to be discarded (Axelrod, 1984).
Axelrod提出的进化方法。就是基于一个原则：对player效果好的会保留，会player不好的会被抛弃

As in game theory, the players use their strategies with each other to achieve a payoff based upon their own choice and the choices of others. In an evolutionary approach, however, there is no need to assume a rational calculation to identify the best strategy. Instead, the analysis of what is chosen at any specific time is based upon an operationalization of the idea that effective strategies are more likely to be retained than ineffective strategies. Moreover, the evolutionary approach allows the introduction of new strategies as occasional random mutations of old strategies.
在博弈论中，玩家需要考虑他们自己的选择和别人的选择来决定strategies。但是在进化方法中，不需要这样的理性计算。选择哪一个策略的分析是基于有效的策略会会保留下来，而无效的策略会被抛弃这样的想法

The evolutionary principle itself can be thought of as the consequence of any one of three different mechanisms.
It could be that the more effective individuals are more likely to survive and reproduce. This is true in biological systems and in some economic and political systems.
A second interpretation is that the players learn by trial and error, keeping effective strategies and altering ones that turn out poorly.
A third interpretation, and the one most congenial to the study of norms, is that the players observe each other, and those with poor performance tend to imitate the strategies of those they see doing better. In any case, there is no need to assume that the individual is rational and understands the full strategic implications of the situation
这种进化原则可以解释为三种不同机制的结果：
1，更有效率的个体更可能生存和复制；
2，学习错误和错误的个体表现差；
3，和这个norm比较合适的个体是那些擅长观察别人，然后模拟比自己表现好的个体。
总而言之，没有必要假设个体是理性的并且理解全部的策略。

The evolutionary approach is inherently probabilistic and involves nonlinear effects. For these reasons, it is often impossible to use deductive mathematics to determine the consequences of a given model. Fortunately, computer simulation techniques (e.g., Cyert and March, 1963) provide a rigorous alternative to deductive mathematics
进化方法是概率的包含非线性影响的，因此不能使用演绎数学来决定一个结果。幸运的可以使用计算机模拟技术。