David Gauthier thinks agents facing a prisoner's dilemma ('pd') should find it rational to dispose themselves to co-operate with those inclined to reciprocate (i.e., to acquire a constrained maximizer--'cm'--disposition), and to co-operate with other 'cmers'. Richmond Campbell argues that since dominance reasoning shows it remains to the agent's advantage to defect, his co-operation is only rational if cm "determines" him to co-operate, forcing him not to cheat. I argue that if cm "forces" the agent to co-operate, he is not acting at all, never mind rationally. Thus, neither author has shown that co-operation is rational action in a pd
