Fragmentation and Representation Processing: Two Distinct Approaches to Information Access, Deduction, and Logical Omniscience

Abstract Ordinary thinkers don’t know every necessary truth - they are not “logically omniscient.” Furthermore, they don’t know everything that follows from their beliefs - they are not “deductively omniscient.” Stalnaker has famously argued that this is partly due to the “fragmentation” of our beliefs, which are divided into different belief-states. Elga and Rayo have developed this idea, arguing that an agent has access to different information under different conditions, such that her doxastic state is divided (“fragmented”) into different informational states. In this article, I distinguish fragmentation from an alternative approach to limited information access. According to this second approach, our limited access to information is explained by our representation-processing mechanisms - the ways in which mental representations are processed by our cognitive systems. I argue that this approach must be sharply distinguished from fragmentation: The limitations that result from our representation-processing mechanisms need not amount to a fragmented doxastic state. The distinction is especially significant given recent objections against fragmentation: Stalnaker’s and Elga and Rayo’s views still seem to attribute an implausible amount of knowledge to ordinary thinkers. I show that an account based on representation processing avoids these objections, thereby opening up a viable alternative to fragmentation.