Indirect reciprocity is generally considered one of the leading mechanisms to explain how cooperation may emerge by natural selection. The basic intuition is that establishing a reputation of being a helpful individual increases the probability of being in turn helped. Two models have been proposed to describe how indirect reciprocity may work: the standing model (Sugden, 1986/2004) and the image-scoring model (Nowak and Sigmund, 1998a,b). Although there is evidence that the former model would perform better under a wide set of circumstances, it is often maintained that it requires individuals with an implausibly large capacity of processing recursive information. In this paper I argue that this is not actually the case. I then suggest that the information needed by the image-scoring model, under reasonable assumptions, may be sufficient for the standing model to work. Finally I emphasize that even if the hypothesis of indirect reciprocity is unable to give a fair account of the ecological bases of cooperation, it has inspired a deal of research precious to social sciences.
