Minimally acceptable altruism and the ultimatum game

I suppose that people react with anger when others show themselves not to be minimally altruistic. I show that, with heterogeneous agents, this can account for the experimental results of ultimatum and dictator games. Moreover, it accounts for the surprisingly large fraction of individuals who offer an even split with parameter values that are more plausible than those that are required to explain outcomes in these experiments with the models of Levine (1998), Fehr and Schmidt (1999), Dickson (2000) and Bolton and Ockenfels (2000).