Accuracy, Coherence and Evidence

Abstract. Taking Joyce’s (1998; 2009) recent argument(s) for probabilism as our point of departure, we propose a new way of grounding formal, synchronic, epistemic coherence requirements for (opinionated) full belief. Our approach yields principled alternatives to deductive consistency, sheds new light on the preface and lottery paradoxes, and reveals novel conceptual connections between alethic and evidential epistemic norms. 1. Setting the Stage This essay is about formal, synchronic, epistemic, coherence requirements. We begin by explaining how we will be using each of these (five) key terms. Formal epistemic coherence requirements involve properties of judgment sets that are logical (and, in principle, determinable a priori). These are to be distin-guished from other less formal and more substantive notions of coherence that one encounters in the epistemological literature. For instance, so-called “coherentists” like BonJour (1985) use the term in a less formal sense which implies (e.g.) that coherence is truth-conducive. While there will be conceptual connections between the accuracy of a doxastic state and its coherence (in the sense we have in mind), these connections will be quite weak (too weak to merit the conventional honorific “truth-conducive”). All of the varieties of coherence to be discussed below will be intimately related to deductive consistency. Consequently, whether a set of judg-ments is coherent will be determined by (i.e., will supervene on) logical properties of the set of propositions that are the objects of the judgments in question. Synchronic epistemic coherence requirements apply to the doxastic states of agents at individual times. These are to be distinguished from diachronic require-ments (e.g., conditionalization, reflection, etc.), which apply to sequences of doxas-tic states across times. Presently, we will be concerned only with the former.