86 CHAPTER THREE ■ InternatIonal relatIons theorIes
structure of an interaction can intervene between intention and outcome to explain
unintended (or harmful) outcomes. It is an effectively realist story, which emphasizes
how the structure of interactions limit the possibility of peace through cooperation.
But neoliberal institutionalists added a startling question: Why assume a single round of
play?
If the prisoner’s dilemma interaction is played repeatedly, the likelihood of reciproc-
ity (known in game theory parlance as “tit for tat”) makes it rational for each prisoner
to cooperate rather than defect. If either prisoner testified against the other in a first
round, then in a second round, that prisoner could expect retaliation. As more rounds
are played, rational players understand they can maximize their expected benefit by
cooperating, and over time, cooperation becomes their preferred or dominant strat-
egy. Similarly, states in the international system are not faced with a one- time round
of “play”: they confront each other repeatedly on a wide range of issues. Unlike classi-
cal liberals, neoliberal institutionalists do not believe that individuals naturally co -
operate out of an innate characteristic of humanity. The prisoner’s dilemma provides
neoliberal institutionalists with a rationale for mutual cooperation in an environment
where no international authority mandates such cooperation.
French president François Hollande and German chancellor Angela Merkel attend a cele
bration of the peaceful Franco German relationship that has endured since the end of World
War II. Liberal theorists believe France’s and Germany’s joint membership in numerous
international organ izations, including the UN, NATO, and the Eu ro pean Union, has supported
this long peace.