ABSTRACT
If is a two letter word that has troubled philosophers and psychologists alike. It cannot be escaped in the study of either reasoning or decision making. To infer a conclusion from premises in reasoning is to commit oneself to holding that the conclusion is true, or at least probably true, if the premises are true. To consider an option in decision making is to think what will happen, or at least probably happen, if the option is taken. If has properties quite unlike other propositional connectives such as and, or and not. In particular, a conditional statement invites the listener to focus on the possibility that its antecedent holds.
