[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

The analytic result (that only 2 of 736 strategically unique ordinal 2×2 games are PDs) is interesting, the numerical simulation less so; the paper doesn't motivate the specific choice of a uniform distribution from which to randomly sample payoffs. (I can imagine the results changing quite a lot if the payoffs are taken from e.g. lognormal or normal distributions instead.)

Wanna bet? I made a few Prediction Book entries. The author was nice enough to give me his source code; I modified it and ran it. I will edit this comment as soon as I finish cranking out the results. I'll rot13 them, or hide them in a spoiler window (is that possible?), for those who'd like to try a Prediction Book probability estimate.

I neglected to make Prediction Book entries for the lognormal distribution, but they would have been similar. Herewith, the results in rot13:

Normal distribution: guerr cbvag sbhe creprag

Lognormal: guerr cbvag svir cre... (read more)