Introduction
Tragedy of the Commons is a situation where a group of individuals have open access to a common resource, acting independently towards their own interest and eventually causing the depletion of the resource through their uncoordinated actions. This phenomenon frequently occurs in the realm of sustainability. For example, fishers in an area might catch more fishes to maximize their own profits, but collectively causing overfishing and depleting their fishery resources. What’s the cause of this? Is this due to a lack of coordination? By modeling this phenomenon as a prisoner’s dilemma, Carrozzo Magli, A., Della Posta, P. and Manfredi, P. discussed the nature of such tragedies.
Modeling the Tragedy
The paper focuses on discussing “sustainability games’, which they defined as a game involving any economic, social or political agents, whose outcome could have a relevant impact on the Earth’s fundamental resources (Carrozzo, Della, Manfredi, 2021). Each player of such games are usually faced with two strategies: a ‘clean’ strategy that costs more money and has less impact on the environment, versus a ‘dirty’ strategy that is cheaper but sacrifices the environment. Intuitively we could associate the ‘clean’ strategy with the ‘stay quiet’ strategy in a prisoner’s dilemma, and the ‘dirty’ strategy with ‘giving out the partner’.
However there are some obvious differences between a sustainability game and a classical prisoner’s dilemma. A sustainability game usually has a huge number of players (agents), instead of having only 2. Also because of this, each agent’s choice has very limited impact on the environment. The paper provides a slightly different modeling to accommodate these differences.
Notice if a player chooses to cooperate while others choose to defect, the player will receive “The sucker’s outcome”, as in a classical prisoner’s dilemma. Furthermore, with a big enough N, for any player in the game, ‘Defect’ is the dominant strategy regardless of what other players do, hence we have a Nash’s Equilibrium at the bottom right cell. Therefore the authors conclude this is indeed a prisoner’s dilemma.
Conclusion
If sustainability games are indeed prisoner’s dilemma, then we are facing a relatively pessimistic future. The Nash Equilibrium is not on our side, without external intervention every agent is going to sacrifice the environment for their own interests. Furthermore this cannot be solved by enhancing coordination, because the Prisoner’s Dilemma is not a coordination game. The dilemma exists even if each player has complete knowledge of all other players. If this is the case then we would need rapid measures to prevent the tragedy from realizing.
References
OECD (2015), “Access to information on social networks, 2013: As a percentage of smartphone users who use the Internet”, in OECD Digital Economy Outlook 2015: , OECD Publishing, Paris, https://doi.org/10.1787/9789264232440-graph84-en.
Carrozzo Magli, A., Della Posta, P., & Manfredi, P. (2021). The Tragedy of the Commons as a Prisoner’s Dilemma. Its Relevance for Sustainability Games. Sustainability, 13(15), 8125. https://doi.org/10.3390/su13158125