A representation theorem for a decision theory with conditionals

This paper investigates the role of conditionals in hypothetical reasoning and rational decision making. Its main result is a proof of a representatio n theorem for preferences defined on sets of sentences (and, in particular, conditional sentences), where an agent's preference for one sentence over another is understood to be a preference for receiving the news conveyed by the former. The theorem shows that a rational preference ordering of condi tional sentences determines probability and desirability representations of the agent's degrees of belief and desire that satisfy, in the case of non- conditional sentences, the axioms of Jeffrey's decision theory and, in the case of conditional sentences, Adams' expression for the probabilities of c onditionals. Furthermore, the probability representation is shown to be uni que and the desirability representation unique up to positive linear transf ormation.