Abstract

A rational subject who believes that a = b, and also believes that j, cannot at the same time disbelieve that j, i.e. believe that not-j. John Searle points out that no such constraint holds for desire and some other propositional attitudes. Which ones, exactly? Where is the divide located and what determines it? These are no minor questions, as they directly bear on the larger issue of how far rationality reaches and the extent to which practical reasoning obeys logical rules. It will be argued that there is no reason for despairing that deductive logic will find a way of dealing with practical reasoning, contrary to Searle’s pessimistic attitude.