Editing Prisoner's dilemma (section)

==Real-life examples==
Many instances of human interaction and natural processes have payoff matrices like the prisoner's dilemma's. It is therefore of interest to the [[social science]]s, such as [[economics]], [[politics]], and [[sociology]], as well as to the biological sciences, such as [[ethology]] and [[evolutionary biology]]. Many natural processes have been abstracted into models in which living beings are engaged in endless games of prisoner's dilemma.

===Environmental studies===
In [[environmental studies]], the dilemma is evident in crises such as global [[climate change]]. It is argued all countries will benefit from a stable climate, but any single country is often hesitant to curb [[Carbon dioxide|{{Co2}}]] emissions. The immediate benefit to any one country from maintaining current behavior is perceived to be greater than the purported eventual benefit to that country if all countries' behavior was changed, therefore explaining the impasse concerning climate-change in 2007.<ref>{{cite news|newspaper=[[The Economist]]|url=http://www.economist.com/finance/displaystory.cfm?story_id=9867020|title=Markets & Data|date=2007-09-27}}</ref>

An important difference between climate-change politics and the prisoner's dilemma is uncertainty; the extent and pace at which pollution can change climate is not known. The dilemma faced by governments is therefore different from the prisoner's dilemma in that the payoffs of cooperation are unknown. This difference suggests that states will cooperate much less than in a real iterated prisoner's dilemma, so that the probability of avoiding a possible climate catastrophe is much smaller than that suggested by a game-theoretical analysis of the situation using a real iterated prisoner's dilemma.<ref>{{cite web|last=Rehmeyer|first=Julie|title=Game theory suggests current climate negotiations won't avert catastrophe|url=https://www.sciencenews.org/article/game-theory-suggests-current-climate-negotiations-won%E2%80%99t-avert-catastrophe|work=Science News|publisher=Society for Science & the Public|date=2012-10-29}}</ref>

Thomas Osang and Arundhati Nandy provide a theoretical explanation with proofs for a regulation-driven win-win situation along the lines of [[Michael Porter]]'s hypothesis, in which government regulation of competing firms is substantial.<ref>{{cite thesis|type=paper|url= http://faculty.smu.edu/tosang/pdf/regln0803.pdf |archive-url=https://web.archive.org/web/20100702083255/http://faculty.smu.edu/tosang/pdf/regln0803.pdf |archive-date=2010-07-02 |url-status=live|first1=Thomas|last1=Osang|first2=Arundhati|last2=Nandyyz|date=August 2003|title=Environmental Regulation of Polluting Firms: Porter's Hypothesis Revisited}}</ref>

===Animals===
Cooperative behavior of many animals can be understood as an example of the iterated prisoner's dilemma. Often animals engage in long-term partnerships; for example, [[guppy|guppies]] inspect predators cooperatively in groups, and they are thought to punish non-cooperative inspectors.<ref>{{cite journal |last1=Brosnan |first1=Sarah F. |last2=Earley |first2=Ryan L. |last3=Dugatkin |first3=Lee A. |title=Observational Learning and Predator Inspection in Guppies ( Poecilia reticulata ): Social Learning in Guppies |journal=Ethology |date=October 2003 |volume=109 |issue=10 |pages=823–833 |doi=10.1046/j.0179-1613.2003.00928.x |doi-access=free }}</ref>

[[Vampire bat]]s are social animals that engage in reciprocal food exchange. Applying the payoffs from the prisoner's dilemma can help explain this behavior.<ref>{{cite book|last=Dawkins|first=Richard|title=The Selfish Gene|year=1976|publisher=Oxford University Press}}</ref>

===Psychology===
In [[addiction]] research and [[behavioral economics]], [[George Ainslie (psychologist)|George Ainslie]] points out that addiction can be cast as an intertemporal prisoner's dilemma problem between the present and future selves of the addict. In this case, "defecting" means relapsing, where not relapsing both today and in the future is by far the best outcome. The case where one abstains today but relapses in the future is the worst outcome: in some sense, the discipline and self-sacrifice involved in abstaining today have been "wasted" because the future relapse means that the addict is right back where they started and will have to start over. Relapsing today and tomorrow is a slightly "better" outcome, because while the addict is still addicted, they haven't put the effort in to trying to stop. The final case, where one engages in the addictive behavior today while abstaining tomorrow, has the problem that (as in other prisoner's dilemmas) there is an obvious benefit to defecting "today", but tomorrow one will face the same prisoner's dilemma, and the same obvious benefit will be present then, ultimately leading to an endless string of defections.<ref>{{cite book |last=Ainslie |first=George |title=Breakdown of Will |year=2001 |publisher=Cambridge University Press |isbn=978-0-521-59694-7}}</ref>

In ''The Science of Trust'', [[John Gottman]] defines good relationships as those where partners know not to enter into mutual defection behavior, or at least not to get dynamically stuck there in a loop. In [[cognitive neuroscience]], fast brain signaling associated with processing different rounds may indicate choices at the next round. Mutual cooperation outcomes entail brain activity changes predictive of how quickly a person will cooperate in kind at the next opportunity;<ref>{{cite journal | author=Cervantes Constantino, Garat, Nicolaisen, Paz, Martínez-Montes, Kessel, Cabana, and Gradin | title=Neural processing of iterated prisoner's dilemma outcomes indicates next-round choice and speed to reciprocate cooperation| journal=Social Neuroscience|year=2020 | volume=16| issue=2| pages=103–120| doi=10.1080/17470919.2020.1859410| pmid=33297873| s2cid=228087900| url=https://doi.org/10.1080/17470919.2020.1859410}}</ref> this activity may be linked to basic homeostatic and motivational processes, possibly increasing the likelihood of short-cutting into mutual cooperation.

===Economics===
The prisoner's dilemma has been called the ''[[Escherichia coli|E. coli]]'' of social psychology, and it has been used widely to research various topics such as [[Oligopoly|oligopolistic]] competition and collective action to produce a collective good.<ref>{{Cite journal|last=Axelrod|first=Robert|date=1980|title=Effective Choice in the Prisoner's Dilemma|journal=The Journal of Conflict Resolution|volume=24|issue=1|pages=3–25|issn=0022-0027|jstor=173932|doi=10.1177/002200278002400101|s2cid=143112198}}</ref>

Advertising is sometimes cited as a real example of the prisoner's dilemma. When [[cigarette advertising]] was legal in the United States, competing cigarette manufacturers had to decide how much money to spend on advertising. The effectiveness of Firm A's advertising was partially determined by the advertising conducted by Firm B. Likewise, the profit derived from advertising for Firm B is affected by the advertising conducted by Firm A. If both Firm A and Firm B chose to advertise during a given period, then the advertisement from each firm negates the other's, receipts remain constant, and expenses increase due to the cost of advertising. Both firms would benefit from a reduction in advertising. However, should Firm B choose not to advertise, Firm A could benefit greatly by advertising. Nevertheless, the optimal amount of advertising by one firm depends on how much advertising the other undertakes. As the best strategy is dependent on what the other firm chooses there is no dominant strategy, which makes it slightly different from a prisoner's dilemma. The outcome is similar, though, in that both firms would be better off were they to advertise less than in the equilibrium.

Sometimes cooperative behaviors do emerge in business situations. For instance, cigarette manufacturers endorsed the making of laws banning cigarette advertising, understanding that this would reduce costs and increase profits across the industry.<ref>{{cite journal |last1=Henriksen |first1=Lisa |title=Comprehensive tobacco marketing restrictions: promotion, packaging, price and place |journal=Tobacco Control |date=March 2012 |volume=21 |issue=2 |pages=147–153 |doi=10.1136/tobaccocontrol-2011-050416 |pmid=22345238 |pmc=4256379 }}</ref>{{efn|1=This argument for the development of cooperation through trust is given in ''[[The Wisdom of Crowds]]'', where it is argued that long-distance [[capitalism]] was able to form around a nucleus of [[Religious Society of Friends|Quakers]], who always dealt honourably with their business partners (rather than defecting and reneging on promises&nbsp;– a phenomenon that had discouraged earlier long-term unenforceable overseas contracts). It is argued that dealings with reliable merchants allowed the [[meme]] for cooperation to spread to other traders, who spread it further until a high degree of cooperation became a profitable strategy in general [[commerce]].}}

Without enforceable agreements, members of a [[cartel]] are also involved in a (multi-player) prisoner's dilemma.<ref>{{Cite book|last1=Nicholson|first1=Walter|year=2000|title=Intermediate microeconomics and its application|edition=8th|location=Fort Worth, TX|publisher=Dryden Press : Harcourt College Publishers|isbn=978-0-030-25916-6}}</ref> "Cooperating" typically means agreeing to a [[price floor]], while "defecting" means selling under this minimum level, instantly taking business from other cartel members. [[Anti-trust]] authorities want potential cartel members to mutually defect, ensuring the lowest possible prices for consumers.

===Sport===
[[Doping in sport]] has been cited as an example of a prisoner's dilemma. Two competing athletes have the option to use an illegal and/or dangerous drug to boost their performance. If neither athlete takes the drug, then neither gains an advantage. If only one does, then that athlete gains a significant advantage over the competitor, reduced by the legal and/or medical dangers of having taken the drug. But if both athletes take the drug, the benefits cancel out and only the dangers remain, putting them both in a worse position than if neither had doped.<ref name="wired">{{cite magazine |last=Schneier |first=Bruce |date=2012-10-26 |title=Lance Armstrong and the Prisoners' Dilemma of Doping in Professional Sports |url=https://www.wired.com/2012/10/lance-armstrong-and-the-prisoners-dilemma-of-doping-in-professional-sports/ |magazine=Wired |publisher=Wired.com |access-date=2012-10-29}}</ref>

===International politics===
In [[international politics|international relations theory]], the prisoner's dilemma is often used to demonstrate why cooperation fails in situations when cooperation between states is collectively optimal but individually suboptimal.<ref>{{Cite journal |last=Snyder |first=Glenn H. |date=1971 |title="Prisoner's Dilemma" and "Chicken" Models in International Politics |url=http://dx.doi.org/10.2307/3013593 |journal=International Studies Quarterly |volume=15 |issue=1 |pages=66–103 |doi=10.2307/3013593 |jstor=3013593 |issn=0020-8833}}</ref><ref>{{Cite journal |last=Jervis |first=Robert |date=1978 |title=Cooperation under the Security Dilemma |url=https://www.cambridge.org/core/journals/world-politics/article/abs/cooperation-under-the-security-dilemma/C8907431CCEFEFE762BFCA32F091C526 |journal=World Politics |language=en |volume=30 |issue=2 |pages=167–214 |doi=10.2307/2009958 |jstor=2009958 |hdl=2027/uc1.31158011478350 |s2cid=154923423 |issn=1086-3338|hdl-access=free }}</ref> A classic example is the [[security dilemma]], whereby an increase in one state's security (such as increasing its military strength) leads other states to fear for their own security out of fear of offensive action.<ref name=":1">{{Cite journal |last=Jervis |first=Robert |date=1978 |title=Cooperation Under the Security Dilemma |url=https://www.jstor.org/stable/2009958 |journal=World Politics |volume=30 |issue=2 |pages=167–214 |doi=10.2307/2009958 |issn=0043-8871 |jstor=2009958 |hdl-access=free |hdl=2027/uc1.31158011478350|s2cid=154923423 }}</ref> Consequently, security-increasing measures can lead to tensions, escalation or conflict with one or more other parties, producing an outcome which no party truly desires.<ref>{{Cite book |last=Herz |first=John H. |title=Idealist Internationalism and the Security Dilemma |year=1950 |pages=157–180}}</ref><ref name=":1" /><ref>{{Cite journal |last=Snyder |first=Glenn H. |date=1984 |title=The Security Dilemma in Alliance Politics |url=https://www.jstor.org/stable/2010183 |journal=World Politics |volume=36 |issue=4 |pages=461–495 |doi=10.2307/2010183 |jstor=2010183 |s2cid=154759602 |issn=0043-8871}}</ref><ref name=":3">{{Cite book |last=Jervis |first=Robert |url=https://books.google.com/books?id=qqAIuHgi2hoC |title=Perception and Misperception in International Politics |date=1976 |publisher=Princeton University Press |isbn=978-0-691-10049-4 |pages=58–113 |language=en}}</ref><ref name=":02">{{Cite book |last=Glaser |first=Charles L. |url=https://press.princeton.edu/titles/9207.html |title=Rational Theory of International Politics |date=2010 |publisher=Princeton University Press |isbn=9780691143729 |access-date= |archive-url= |archive-date= }}</ref> The security dilemma is particularly intense in situations when it is hard to distinguish offensive weapons from defensive weapons, and offense has the advantage in any conflict over defense.<ref name=":1" />

The prisoner's dilemma has frequently been used by [[Realism (international relations)|realist]] international relations theorists to demonstrate the why all states (regardless of their internal policies or professed ideology) under [[anarchy (international relations)|international anarchy]] will struggle to cooperate with one another even when all benefit from such cooperation.

Critics of realism argue that iteration and extending the shadow of the future are solutions to the prisoner's dilemma. When actors play the prisoner's dilemma once, they have incentives to defect, but when they expect to play it repeatedly, they have greater incentives to cooperate.<ref>{{Cite journal |last1=Axelrod |first1=Robert |last2=Hamilton |first2=William D. |date=1981 |title=The Evolution of Cooperation |url=https://www.science.org/doi/10.1126/science.7466396 |journal=Science |language=en |volume=211 |issue=4489 |pages=1390–1396 |doi=10.1126/science.7466396 |pmid=7466396 |bibcode=1981Sci...211.1390A |issn=0036-8075}}</ref>

===Multiplayer dilemmas===
Many real-life dilemmas involve multiple players.<ref>Gokhale CS, Traulsen A. Evolutionary games in the multiverse. Proceedings of the National Academy of Sciences. 2010 Mar 23. 107(12):5500–04.</ref> Although metaphorical, [[Garrett Hardin]]'s [[tragedy of the commons]] may be viewed as an example of a multi-player generalization of the prisoner's dilemma: each villager makes a choice for personal gain or restraint. The collective reward for unanimous or frequent defection is very low payoffs and the destruction of the commons.

The commons are not always exploited: [[William Poundstone]], in a book about the prisoner's dilemma, describes a situation in New Zealand where newspaper boxes are left unlocked. It is possible for people to [[Excludability|take a paper without paying]] (defecting), but very few do, feeling that if they do not pay then neither will others, destroying the system.{{sfn|Poundstone|1993|pp=126–127}} Subsequent research by [[Elinor Ostrom]], winner of the 2009 [[Nobel Memorial Prize in Economic Sciences]], hypothesized that the tragedy of the commons is oversimplified, with the negative outcome influenced by outside influences. Without complicating pressures, groups communicate and manage the commons among themselves for their mutual benefit, enforcing social norms to preserve the resource and achieve the maximum good for the group, an example of effecting the best-case outcome for prisoner's dilemma.<ref>{{cite web|url=http://volokh.com/2009/10/12/elinor-ostrom-and-the-tragedy-of-the-commons/ |title=The Volokh Conspiracy " Elinor Ostrom and the Tragedy of the Commons |publisher=Volokh.com |date=2009-10-12 |access-date=2011-12-17}}</ref><ref>{{cite book |last1=Ostrom |first1=Elinor |title=Governing the Commons: The Evolution of Institutions for Collective Action |date=2015 |orig-year=1990 |publisher=Cambridge University Press |isbn=978-1-107-56978-2 |doi=10.1017/CBO9781316423936}}</ref>

=== Academic settings ===

The prisoner's dilemma has been used in various academic settings to illustrate the complexities of cooperation and competition. One notable example is the classroom experiment conducted by sociology professor Dan Chambliss at [[Hamilton College]] in the 1980s. Starting in 1981, Chambliss proposed that if no student took the final exam, everyone would receive an A, but if even one student took it, those who didn't would receive a zero. In 1988, [[John K. Werner|John Werner]], a first-year student, successfully organized his classmates to boycott the exam, demonstrating a practical application of game theory and the prisoner's dilemma concept.<ref name="insidehighered">{{cite web |url=https://www.insidehighered.com/news/2013/02/22/look-back-another-successful-final-exam-boycott |title=A look back at another successful final exam boycott |author=Rivard, Ry |publisher=Inside Higher Ed |date=2013-02-21 |access-date=2024-07-12}}</ref>

Nearly 25 years later, a similar incident occurred at [[Johns Hopkins University]] in 2013. Professor Peter Fröhlich's grading policy scaled final exams according to the highest score, meaning that if everyone received the same score, they would all get an A. Students in Fröhlich's classes organized a boycott of the final exam, ensuring that no one took it. As a result, every student received an A, successfully solving the prisoner's dilemma in a mutually optimal way without iteration.<ref name="nyt">{{cite web |url=https://archive.nytimes.com/economix.blogs.nytimes.com/2013/02/14/gaming-the-system/ |title=Gaming the System |author=Wolfers, Justin |work=The New York Times |date=2013-02-14 |access-date=2024-07-12}}</ref><ref name="baltimorefishbowl">{{cite web |url=https://baltimorefishbowl.com/stories/johns-hopkins-students-boycott-final-exam-so-everyone-gets-an-a/ |title=Johns Hopkins Students Boycott Final Exam - So Everyone Gets an A |publisher=Baltimore Fishbowl |date=2013-02-25 |access-date=2024-07-12}}</ref> These examples highlight how the prisoner's dilemma can be used to explore cooperative behavior and strategic decision-making in educational contexts.