[LINK] Prisoner's Dilemma? Not So Much

torekp

Hannes Rusch argues that the Prisoner's Dilemma is best understood as merely one game of very many:

only 2 of the 726 combinatorially possible strategically unique ordinal 2x2 games have the detrimental characteristics of a PD and that the frequency of PD-type games in a space of games with random payoffs does not exceed about 3.5%. Although this does not compellingly imply that the relevance of PDs is overestimated, in the absence of convergent empirical information about the ancestral human social niche, this finding can be interpreted in favour of a rather neglected answer to the question of how the founding groups of human cooperation themselves came to cooperate: Behavioural and/or psychological mechanisms which evolved for other, possibly more frequent, social interaction situations might have been applied to PD-type dilemmas only later.

http://www2.units.it/etica/2013_2/RUSCH.pdf

Hannes Rusch argues that the Prisoner's Dilemma is best understood as merely one game of very many:

only 2 of the 726 combinatorially possible strategically unique ordinal 2x2 games have the detrimental characteristics of a PD and that the frequency of PD-type games in a space of games with random payoffs does not exceed about 3.5%. Although this does not compellingly imply that the relevance of PDs is overestimated, in the absence of convergent empirical information about the ancestral human social niche, this finding can be interpreted in favour of a rather neglected answer to the question of how the founding groups of human cooperation themselves came to cooperate: Behavioural and/or psychological mechanisms which evolved for other, possibly more frequent, social interaction situations might have been applied to PD-type dilemmas only later.

http://www2.units.it/etica/2013_2/RUSCH.pdf

Looks like they deliberately use a conservative formulation of the "detrimental characteristics of a PD." Both players are required to have a dominant strategy, that leads to a situation where both are worse off than the optimal square.

A more expansive formulation would be something like "there is a Nash equilibrium that is not Pareto optimal." If the preference-ranking version of the PD is something like [[11],[24]][[42],[33]], this means that we'd also notice something interesting about the game [[22],[14]][[41],[43]], etc.

there is a Nash equilibrium that is not Pareto optimal

Like Stag Hunt.

What they argue is that mechanisms for producing mutual cooperation in games like your more expansive formulation but that don't match the deliberately conservative formulation might have been important in the evolution of cooperativeness.

6torekp12y

I find the narrow definition of "PD-type" games useful. You raise a good question though, to which the author's answer is [...]