quality:corruption
The "obligatory reciprocal altruism" hypothesis

Ib Ulbæk invokes another standard Darwinian principle—" reciprocal altruism " —to explain the unusually high levels of intentional honesty necessary for language to evolve. "Reciprocal altruism" can be expressed as the principle that if you scratch my back, I'll scratch yours. In linguistic terms, it would mean that if you speak truthfully to me, I'll speak truthfully to you. Ordinary Darwinian reciprocal altruism, Ulbæk points out, is a relationship established between frequently interacting individuals. For language to prevail across an entire community, however, the necessary reciprocity would have needed to be enforced universally instead of being left to individual choice. Ulbæk concludes that for language to evolve, society as a whole must have been subject to moral regulation.

Critics point out that this theory fails to explain when, how, why or by whom "obligatory reciprocal altruism" could possibly have been enforced. Various proposals have been offered to remedy this defect. A further criticism is that language does not work on the basis of reciprocal altruism anyway. Humans in conversational groups do not withhold information to all except listeners likely to offer valuable information in return. On the contrary, they seem to want to advertise to the world their access to socially relevant information, broadcasting that information without expectation of reciprocity to anyone who will listen.