For those outside Australia, the Garnaut Climate Change Review is our equivalent of the Stern Review and last week a draft report was released. In this report, a nation’s decision as to how to act in the face of climate change is compared to the prisoner’s dilemma:
Effective international action is necessary if the risks of dangerous climate change are to be held to acceptable levels, but deeply problematic. International cooperation is essential for a solution to a global problem. However, such a solution requires the resolution of a genuine prisoners’ dilemma. Each country benefits from a national point of view if it does less of the mitigation itself, and others do more. If all countries act on this basis, without forethought and cooperation, there will be no resolution of the dilemma.
A staple of game theory, the classic formulation of the prisoner’s dilemma goes something like this. You have been arrested, along with your partner in crime. The two of you have been separated and are under interrogation. The police are light on evidence and they offer both of you the same deal. If you are the only one to talk, the reward for cooperation is that you go free, but your silent partner gets a ten year sentence. If both of you talk, your evidence is not so valuable, but your cooperation is still noted and you both receive a reduced sentence of five years. However, if both of you keep quiet, the lack of evidence means that you will both only get six months in jail. What should you do?
The classical analysis says you should always blab because no matter what your partner does, you will be better off. If he or she stays quiet, you will go free rather than getting five years, while if he or she spills the beans too, then you will get five years rather than ten. Of course, the problem is that if both of you follow the same reasoning, you will both get five years when a bit of cooperation would have resulted in a better outcome overall with only six months each.
If that was all there was to the analysis, it would paint a grim picture for international action on climate change. However, the situation changes significantly when you get to play the “game” repeatedly and you can both take into account each other’s previous behaviour. The mathematically formalised version of the game, known as the Iterated Prisoner’s Dilemma (IPD), has no police, no prison cells, just a series of decisions to either attack your opponent (i.e. blabbing) or to cooperate (staying silent) and scores for each outcome (the sentences). Famously, political scientist Robert Axelrod arranged a tournament in 1980 in which different computer algorithms were pitted against one another playing IPD. Strategies included randomly attacking or cooperating, always attacking or always cooperating. The winning strategy in the tournament, known as “Tit-for-Tat”, would intially cooperate but, if attacked, would attack back. Likewise, it was quick to forgive and would reciprocate any cooperation. Evolutionary theorists* have latched on to this phenomenon as an explanation for how cooperative behaviour can evolve in a natural world which we would otherwise expect to always be red in tooth and claw.
Of course, international diplomacy is certainly iterated over a long period of time, and so cooperation is an extremely powerful technique (admittedly some would argue that we don’t need computer tournaments to show us this!). While some point to the fact that Australia only contributes around 1.5% of world emissions to justify inaction (putting aside the fact that we are one of the highest per capita emitters), this ignores the fact that decisive action on the part of Australia will put us in a far better position to influence the behaviour of other countries. The applause Rudd received in Bali when announcing that Australia would ratify the Kyoto protocol shows how effective Tit-for-Tat can be.
* For more on the evolutionary biology story, an excellent account can be found in Matt Ridley’s book “The Origins of Virtue“.
Thanks to Nicole from the Climate Group for alerting me to some broken links.