Ken Binmore Origins of Fair Play

John Mackie’s Inventing Right and Wrong Metaphysical moral philosophy is unsound. Look instead at: Anthropology Game theory

Social Contracts No bosses Fair division The social contracts of pure hunter-gatherer societies have two universal properties:

Pure hunter-gatherers

Toy games dove hawk Prisoners’ Dilemma dove hawk Stag Hunt Adam’s strategies

Toy games Prisoners’ Dilemma Stag Hunt dovehawkdovehawk Eve’s strategies

Toy games dove hawk Prisoners’ Dilemma dove hawk Stag Hunt dovehawkdovehawk Adam’s payoffs

Toy games dove hawk Prisoners’ Dilemma dove hawk Stag Hunt dovehawkdovehawk Eve’s payoffs

Toy games dove hawk Prisoners’ Dilemma dove hawk Stag Hunt dovehawkdovehawk

Nash Equilibria dove hawk Prisoners’ Dilemma dove hawk Stag Hunt dovehawkdovehawk

Coordination Games left right Driving Game box ball Battle of the Sexes leftrightboxball

Reciprocal Altruism indefinitely repeated Prisoners’ Dilemma

Reciprocal Altruism dh d Grim strategy h

Reputation and Trust Sure I trust him. You know the ones to trust in this business. The ones who betray you, bye-bye.

Vampire bats share blood on a reciprocal basis to insure each other against hunger.

Folk Theorem efficient equilibria current status quo Eve’s payoff Adam’s payoff 0

Equilibrium selection Fairness is evolution’s solution to the equilibrium selection problem.

Equilibrium selection Fairness is evolution’s solution to the equilibrium selection problem. Fairness therefore evolved as a means of balancing power---not as a substitute for power.

Deep structure of fairness norms As with language, fairness has a deep structure that is universal in the human species. This deep structure is embodied in Rawls’ original position

John Rawls’ original position Veil of ignorance Comparison of welfare Enforcement

I might be Adam and Oskar might be Eve. Or Oskar might be Adam and I might be Eve Original Position Adam Eve Oskar John

implicit insurance contracts deep structure of fairness? implicit insurance contracts

original position deep structure of fairness? original position

implicit insurance contracts original position utilitarianismegalitarianism external enforcement self-policing Who is right? Harsanyi Rawls

Modern Equity Theory What is fair … is what is proportional. Aristotle Eve Adam 0 status quo slope is ratio of the players’ context-dependent social indices

implicit insurance contracts original position utilitarianismegalitarianism external enforcement self-policing standard of interpersonal comparison cultural evolution

... 0 Adam’s payoff Eve’s payoff Utilitarianism and Egalitarianism The slopes are determined by the standard of interpersonal comparison. utilitarian outcome egalitarian outcome state of nature

... 0 Adam’s payoff Eve’s payoff Utilitarianism and Egalitarianism The slopes are determined by the standard of interpersonal comparison. utilitarian outcome egalitarian outcome

.. 0 Adam’s payoff Eve’s payoff Utilitarianism and Egalitarianism The slopes are determined by the standard of interpersonal comparison. utilitarian outcome egalitarian outcome

.. 0 Utilitarianism and Egalitarianism The slopes are determined by the standard of interpersonal comparison. Nash bargaining solution

.. 0 Cultural Evolution: Egalitarian Case medium-run past Nash bargaining solution. short-run present egalitarian solution

Analogy with language Chomsky discovered that all languages have a deep structure which is universal in the human species, but the particular language spoken in a society is determined by its cultural history. Fairness norms similarly have a common deep structure, but the standard of interpersonal comparison that is necessary as an input to the original position is culturally determined.

Moral relativism Need Ability Effort Status Social indices always respond to these parameters in the same way, but the degree of response varies with a society’s cultural history.

Reform?