Objective probability and the assessment of evidence

Abstract

As accounts of evidential reasoning, theories of subjective probability face a serious limitation: they fail to show how features of the world should constrain probability assessments. This article surveys various theories of objective probability, noting how they overcome this problem, and highlighting the difficulties there might be in applying them to the process of fact-finding in trials. The survey highlights various common problems which theories of objective probability must confront. The purpose of the survey is, in part, to shed light on an argument about the use of Bayes' rule in fact-finding recently made by Alvin Goldman. But the survey is also intended to highlight important features of evidential reasoning that have received relatively little attention from evidence scholars: the role categorization plays in reasoning, and the link between probability and wider theories of epistemic justification.