[philipov]

One should be hesitant to proclaim knowledge of the optimal strategy without knowing all the details. Whether or not the default strategy is to cooperate or betray is sensitive to the precise weights of the rewards for each combination of decisions, as well as the number of times the game is played. For example, in the simple version of the Iterated Prisoner's Dilemma, the optimal strategy is tit-for-tat: the default is to cooperate, and only betray in exchange for being betrayed.