Complexity_ A Guided Tour - Melanie Mitchell [106]
Inspire new technologies. Results from the Prisoner’s Dilemma modeling literature—namely, the conditions needed for cooperation to arise and persist—have been used in proposals for improving peer-to-peer networks and preventing fraud in electronic commerce, to name but two applications.
Lead to mathematical theories. Several people have used the results from Prisoner’s Dilemma computer simulations to formulate general mathematical theories about the conditions needed for cooperation. A recent example is work by Martin Nowak, in a paper called “Five Rules for the Evolution of Cooperation.”
How should results from idea models such as the Prisoner’s Dilemma be used to inform policy decisions, such as the foreign relations strategies of governments or responses to global warming? The potential of idea models in predicting the results of different policies makes such models attractive, and, indeed, the influence of the Prisoner’s Dilemma and related models among policy analysts has been considerable.
As one example, New Energy Finance, a consulting firm specializing in solutions for global warming, recently put out a report called “How to Save the Planet: Be Nice, Retaliatory, Forgiving, and Clear.” The report argues that the problem of responding to climate change is best seen as a multi-player repeated Prisoner’s Dilemma in which countries can either cooperate (mitigate carbon output at some cost to their economies) or defect (do nothing, saving money in the short term). The game is repeated year after year as new agreements and treaties regulating carbon emissions are forged. The report recommends specific policies that countries and global organizations should adopt in order to implement the “nice, retaliatory, forgiving, and clear” characteristics Axelrod cited as requirements for success in the repeated Prisoner’s Dilemma.
Similarly, the results of the norms and metanorms models—namely, that not only norms but also metanorms can be important for sustaining cooperation—has had impact on policy-making research regarding government response to terrorism, arms control, and environmental governance policies, among other areas. The results of Nowak and May’s spatial Prisoner’s Dilemma models have informed people’s thinking about the role of space and locality in fostering cooperation in areas ranging from the maintenance of biodiversity to the effectiveness of bacteria in producing new antibiotics. (See the notes for details on these various impacts.)
Computer Modeling Caveats
All models are wrong, but some are useful.
—George Box and Norman Draper
Indeed, the models I described above are highly simplified but have been useful for advancing science and policy in many contexts. They have led to new insights, new ways of thinking about complex systems, better models, and better understanding of how to build useful models. However, some very ambitious claims have been made about the models’ results and how they apply in the real world. Therefore, the right thing for scientists to do is to carefully scrutinize the models and ask how general their results actually are. The best way to do that is to try to replicate those results.
In an experimental science such as astronomy or chemistry, every important experiment is replicated, meaning that a different group of scientists does the same experiment from scratch to see whether they get the same results as the original group. No experimental result is (or should be) believed if no other group can replicate it in this way. The inability of others to replicate