Epistemic Utility and Norms for Credences (original) (raw)

Beliefs come in different strengths. An agent's credence in a proposition is a measure of the strength of her belief in that proposition. Various norms for credences have been proposed. Traditionally, philosophers have tried to argue for these norms by showing that any agent who violates them will be lead by her credences to make bad decisions. In this article, we survey a new strategy for justifying these norms. The strategy begins by identifying an epistemic utility function and a decision-theoretic norm; we then show that the decision-theoretic norm applied to the epistemic utility function yields the norm for credences that we wish to justify. We survey results already obtained using this strategy, and we suggest directions for future research. Like the rest of us, Paul's beliefs come in degrees. Some are stronger than others. In particular , Paul believes that Linda is a bank teller and a political activist more strongly than he believes that she is a bank teller. That is, his credence in the former proposition is greater than his credence in the latter. Surely, Paul is irrational. But why? 1 In this survey, I describe a new strategy for answering such questions. It is a strategy that was first introduced by Jim Joyce (1998). The traditional strategy-the strategy that Joyce sought to replace or, at least, supplement is to show that such credences will lead the agent who has them to make decisions that are guaranteed to have a bad outcome. These are the well-known Dutch Book arguments. 2 For instance, Paul's credences will lead him to buy a book of bets on the two propositions concerning Linda that is guaranteed to lose him money. This, it is claimed, makes him irrational. Now, the validity of this argument has been the subject of much debate. However, even if it works, it only identifies one way in which Paul's credences are irrational: they are poor guides to action; from a pragmatic point of view, they are irrational. But, intuitively, there is something irrational about these credences from a purely epistemic point of view; they seem to exhibit a purely epistemic flaw. Even for an agent incapable of acting on her credences-and therefore incapable of making the bets that lead to the guaranteed loss-Paul's credences would be irrational. We will be concerned with identifying why that is so. That is, Joyce's strategy, which we describe here, provides a purely epistemic route to the norms that govern credences; this route does not rely on any connection between credence and action. We will begin by showing how the strategy works in the case of Paul. Then, we will show how to extend it to establish probabilism, which is the norm that Joyce considers in his original paper. Probabilism is one of the core tenets of so-called Bayesian episte-mology. Our next target is the other core tenet of that view, namely, conditionalization. We will give an argument for that norm that uses Joyce's strategy as well: it is due to Hilary Greaves and David Wallace (2006). After considering how we might strengthen these arguments by weakening the assumptions they make, we conclude by describing possible avenues for future research.