Two-level game theory
Two-level game theory
thumb|Five of the seven leaders at the 1978 G7 Economic Summit in Bonn. From left to right: Giulio Andreotti (Italy), Takeo Fukuda (福田 赳夫) (Japan), Jimmy Carter (USA), Helmut Schmidt (West Germany) and Valéry d'Estaing (France).Two-level game theory is a political model, derived from game-theory, that illustrates the domestic-international interactions between states. It was originally introduced in 1988 by Robert D. Putnam in his publication "Diplomacy and Domestic Politics: The Logic of Two-Level Games".
Putnam had been involved in research around the G7 summits between 1976 and 1979. However, at the fourth summit, held in Bonn in 1978, he observed a qualitative shift in how the negotiations worked. He noted that attending countries agreed to adopt policies in contrast to what they might have in the absence of their international counterparts. However, the agreement was only viable due to strong domestic influence - within each international government - in favour of implementing the agreement internationally. This culminated in international policy co-ordination as a result of the entanglement of international and domestic agendas. Due to a potential difference in domestic concerns, the full range of agreement outcomes at the international level may not necessarily be approved. As such, the possible agreement outcomes at the international level that are accepted by domestic interest groups is defined as a state's "win-set". As a classic case of the prisoner's-dilemma, states are therefore more incentivised to do nothing, rather than contributing to mitigating climate change. This unequal burden-sharing has led to varying conceptions between states of what is fair under the Paris Agreement, resulting in both small and large countries utilising their negotiating assets to arrive at an agreement.