 For Axelrod, who studied these issues primarily in the context of repeated prisoner’s dilemmas, the two requirements identified above amount to the same thing. A strategy of unconditional cooperation allows an individual to be repeatedly taken advantage of. To prevent this she should only cooperate with those who are similarly willing to cooperate. More precisely, she should be nice (that is she should initially be willing to cooperate with anyone), but she should also be provocable (that is she should be prepared to stop cooperating with anyone who takes advantage of her, at least for some amount of time). And, because sustained cooperation is in everybody’s long-run interest, in this context withdrawing future cooperation as a consequence for being taken advantage of is a form of punishment.