Abstract
A considerable share of the literature on the evolution of human cooperation considers the question why we have not evolved to play the Nash equilibrium in prisoners' dilemmas or public goods games. In order to understand human morality and pro-social behaviour, we suggest that it would actually be more informative to investigate why we have not evolved to play the subgame perfect Nash equilibrium in sequential games, such as the ultimatum game and the trust game. The 'rationally irrational' behaviour that can evolve in such games gives a much better match with actual human behaviour, including elements of morality such as honesty, responsibility and sincerity, as well as the more hostile aspects of human nature, such as anger and vengefulness. The mechanism at work here is commitment, which does not need population structure, nor does it need interactions to be repeated. We argue that this shift in focus can not only help explain why humans have evolved to know wrong from right, but also why other animals, with similar population structures and similar rates of repetition, have not evolved similar moral sentiments. The suggestion that the evolutionary function of morality is to help us commit to otherwise irrational behaviour stems from the work of Robert Frank (American Economic Review, 77(4), 593-604, 1987; Passions within reason: The strategic role of the emotions, WW Norton, 1988), which has played a surprisingly modest role in the scientific debate to date.
Highlights
If we paint the mechanisms at work with a broad brush, in most of those models, cooperation evolves because of population structure or because of repeated interactions between players, with partner choice coming in third at a respectable distance
Prisoners’ dilemmas and public goods games We have looked at reasons why predictions from models with prisoners’ dilemmas do not match deviations from simple selfishness in games like the ultimatum game or the trust game
The recurrent theme is that these deviations are bad for fitness, but being committed to them can be good. This is true for rejections in the ultimatum game, for sending back money in the trust game, for truly caring for each other in the insurance game, and for punishing defections in prisoners’ dilemmas or public goods games with the option to punish
Summary
There is an extensive theoretical literature on the evolution of cooperation. Most papers in this literature (including our own) present models in which individuals play prisoners’ dilemmas, or public goods games, and look for ways in which cooperation can outperform defection. If we paint the mechanisms at work with a broad brush, in most of those models, cooperation evolves because of population structure (which often means that it can be seen as kin selection) or because of repeated interactions between players, with partner choice coming in third at a respectable distance. Rejections would be pro-social, if they increased the fitness of the other player, but that is not what they do; they reduce the fitness for both players involved If commitment evolves, it does not necessarily advance the common good; it can do that, as we will see, in games like the trust game, but in games like the ultimatum game, it just helps individuals secure a larger share of a fixed-size pie.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
