Indirect reciprocity is the most elaborate and cognitively demanding of all known cooperation mechanisms, and is the most specifically human because it involves reputation and status. By helping someone, individuals may increase their reputation, which may change the predisposition of others to help them in future. The revision of an individual’s reputation depends on the social norms that establish what characterizes a good or bad action and thus provide a basis for morality. Norms based on indirect reciprocity are often sufficiently complex that an individual’s ability to follow subjective rules becomes important, even in models that disregard the past reputations of individuals, and reduce reputations to either ‘good’ or ‘bad’ and actions to binary decisions. Here we include past reputations in such a model and identify the key pattern in the associated norms that promotes cooperation. Of the norms that comply with this pattern, the one that leads to maximal cooperation (greater than 90 per cent) with minimum complexity does not discriminate on the basis of past reputation; the relative performance of this norm is particularly evident when we consider a ‘complexity cost’ in the decision process. This combination of high cooperation and low complexity suggests that simple moral principles can elicit cooperation even in complex environments.

中文翻译：

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合作演变中的社会规范复杂性和过去的声誉

间接互惠是所有已知合作机制中最精细和认知要求最高的，也是最具体的人，因为它涉及声誉和地位。通过帮助某人，个人可能会提高他们的声誉，这可能会改变其他人将来帮助他们的倾向。个人声誉的修正取决于社会规范，这些规范确定了好坏行为的特征，从而为道德提供了基础。基于间接互惠的规范通常非常复杂，以至于个人遵循主观规则的能力变得很重要，即使在忽略个人过去声誉并将声誉降低为“好”或“坏”并将行为降低为二元决策的模型中也是如此。在这里，我们将过去的声誉包含在这样的模型中，并确定了促进合作的相关规范中的关键模式。在符合这种模式的规范中，导致最大程度合作（大于 90%）和最小复杂性的规范不会根据过去的声誉进行歧视；当我们在决策过程中考虑“复杂性成本”时，该规范的相对表现尤为明显。这种高度合作和低复杂性的结合表明，即使在复杂的环境中，简单的道德原则也能引发合作。当我们在决策过程中考虑“复杂性成本”时，该规范的相对表现尤为明显。这种高度合作和低复杂性的结合表明，即使在复杂的环境中，简单的道德原则也能引发合作。当我们在决策过程中考虑“复杂性成本”时，该规范的相对表现尤为明显。这种高度合作和低复杂性的结合表明，即使在复杂的环境中，简单的道德原则也能引发合作。