The Tragedy of the Commons and The Prisoner’s Dilemma. Thomas Malthus. 1798, writes critique of Condorcet et al Food supplies increase additively (linear) Population increases geometrically (nonlinear). Thomas Malthus. Malthus argued that two types of checks hold population within resource
The Tragedy of the CommonsandThe Prisoner’s Dilemma
"A Theory of Population" (1852)
is like feeding rats: you only get more rats
The Universal Declaration of Human Rights describes the family as the natural and fundamental unit of society. [Article 16] It follows that any choice and decision with regard to the size of the family must irrevocably rest with the family itself, and cannot be made by anyone else.
Game Theory Approach to the Psychology of the Commons: The Prisoner’s Dilemma
You have diamonds, your dealer has money.
You both agree to leave bags at designated places in forest:
You leave a full bag, but his bag is empty. You get ripped off.
You leave an empty bag, he leaves a full one. You have doubled your wealth.
You leave an empty bag, and he leaves an empty bag: no worse off than you are already.
Therefore, economic “rationalism” demands that you leave an empty bag. Since the dealer is in the same situation, you both receive nothing.
The Prisoner’s Dilemma
You have both been accused of a crime:
You both stay mum, you each get 2 years in jail
You rat out your partner: you are free, he gets 5
You both rat each other out, you each get 4 years in jail
“Rational self-interest” gives a sub-optimum result!
RAND in 1950s: US and USSR each want to eliminate nukes
The Prisoner’s Dilemma applies to many situations in which lack of trust destroys our ability to cooperate
The Prisoner’s Dilemma: canonical version
Two players have the choice of cooperating or defecting.
Temptation to defect is the highest payoff (5)
Reward for mutual cooperation is second highest payoff (3)
Punishment for mutual defection is third highest (1)
Sucker’s payoff (cooperating during defect) is lowest (0)
T>R>P>S and (T+S)/2 < R are required conditions
More generally, this is
A “Nash Equilibrium”
The Iterated Prisoner’s Dilemma:
Robert Axelrod 1979
The Iterated Prisoner’s Dilemma winner: Rapoport’s tit for tat
The Iterated Prisoner’s Dilemma winner: Rapoport’s Tit for Tat
Spatial prisoner’s dilemma (Martin Nowak)
Runs like cellular automaton
Spatial structure allows “islands” of cooperation to rise in sea of defectors
Why don’t “freeloaders”
rise in genetic
The Side-Blotched Lizard (Utastansburiana) is polymorphic with
three morphs that each pursues a different mating strategy
1) The Orange throat is very aggressive and operates over a large territory - attempting to mate with numerous females within this larger area
2) The unaggressive Yellow Throat (called “sneakers”) mimic the markings/behavior of female lizards and sneakily slip into the Orange Throat's territory to mate with the females there (thereby overtaking the population), and
3) The Blue Throat who mates with and carefully guards ONE female - making it impossible for the sneakers to succeed and therefore overtakes their place in a population…