Conditionals and the logic of decision

In this paper Richard Jeffrey's 'Logic of Decision' is extended by examinat ion of agents' attitudes to the sorts of possibilities identified by indica tive conditional sentences. An expression for the desirability of condition als is proposed and, along with Adams' thesis that the probability of a con ditional equals the conditional probability of its antecedent given its con sequent, is defended by informally deriving it from Jeffrey's notion of des irability and some weak constraints on rational preference for conditional possibilities. Finally a statement is given of a representation theorem est ablishing the conditions under which a rational agent's preferences for con ditionals determines the existence of unique measures (up to choice of scal e) of her degrees of belief and desire.