This work briefly discusses one of the central problems in the current psychology of reasoning: that of explaining the effects of content. T w o competing theories recently proposed to explain such effects (pragmatic reasoning schemas and social contract theories) are illustrated with reference to an experiment on reasoning in children employing a selection problem, which requires a search for the potential counterexamples of a conditional rule. On the one hand, the theory of pragmatic schemas (i.e. clusters of rules related to pragmatically relevant actions and goals) predicts that correct selection performance derives from the activation of specific contractual schemas, such as obligation and permission, the production rules of which correspond to the logic of implication. On the other hand, according to the social contract theory, people are able to detect potential counterexamples only when they correspond to the potential cheaters of rules having the form 'If benefit A is received, then cost B must be paid'. The results of the experiment show that performance on tasks of this kind is not determined simply by the possibility of representing the rule in question in cost-benefit terms; to predict performance one necessary factor is knowledge of the nature of the possible cheating behaviour that one is requested to check.