The probability that the other party will not act ina harmful way is raised by the understanding that mutual interest makes defection costly enough to be deterred. The soldiers' belief that they can trust each other results from an inference concerning the effectiveness of their interests as a motive for rational action in initiating and maintaining cooperation. Thus p is raised in the ' course of cooperation itself, without any assumption being made as to prior levels: 'The cooperative exchanges of mutual restraint actually changed the nature of the interaction. They tended to make the two sides care about each other's welfare' (Axelrod 1984: 85).

XREF: Echoes game theory and Axelrod's iterated prisoner's dilemma, where repeated cooperation fosters trust without prior assumptions. Builds on: "Optimal cooperation emerges without deliberate manipulation of arrangements."

Diego Gambetta, Trust - Making and Breaking…, loc. 2792