People in these societies therefore fail to cooperate, in part because it would do no good in many contexts and in part because they naturally focus on the competitive, zero-sum aspects of their lives. If there is no point in cooperation, there may even be advantage in deceit, secrecy, and cheating, as there typically is in a zero-sum conflict. Of course, if everyone outside my family is likely to cheat me, I have good reason not to trust them.

Russell Hardin, Trust and Trustworthiness, loc. 473