Probabilistic models of legal corroboration

Abstract

The aim is to develop a sensible probabilistic model of legal corroboration in response to an attack on the probabilistic approach to legal reasoning due to Cohen. One of Cohen’s arguments is that there is no probabilistic measure of evidential support which satisfactorily captures the situation in which independent witnesses testify to the truth of the same proposition (or independent pieces of evidence converge on a certain claim)—the phenomenon called corroboration (or convergence). We investigate the properties of several probabilistic measures discussed by Cohen, discuss Cohen’s criticism of those measures, and develop our own. Finally, we offer a probabilistic measure of corroboration that evades the critical points raised against the ones discussed so far.