Josh Brekel

John Maynard Keynes’s concept of the weight of evidence is one of the most enduring—and mysterious—features of Keynes’s epistemology. One popular interpretation of Keynesian weight comes courtesy of Jochen Runde, who argues that weight is best construed as the ratio of the amount of known relevant evidence to the amount of total relevant information. Runde’s interpretation aims to establish a strong link between Keynesian weight and rational confidence, which in turn is meant to bolster the connection between Keynesian weight of evidence and Keynes’s later economic work. Despite this advantage, Runde’s interpretation also implies the existence of significant inconsistencies in Keynes’s account of weight of evidence. As a consequence, Runde’s interpretation paints Keynes as particularly confused about Keynesian weight of evidence. In this work, I provide a distinction between estimated Keynesian weight and actual Keynesian weight in order to preserve the desirable features of Runde’s interpretation while simultaneously resolving the textual inconsistencies that arise from that interpretation. The upshot is a novel interpretation that makes Keynesian weight less ambiguous, more consistent with the rest of Keynes’s epistemology, and better-situated for future research.