Abstract

The formal representation of the strength of witness testimony has been historically tied to a formula — proposed by Condorcet — that uses a factor representing the reliability of an individual witness. This approach encourages a false dilemma between hyper-scepticism about testimony, especially to extraordinary events such as miracles, and an overly sanguine estimate of reliability based on insufficiently detailed evidence. Because Condorcet’s formula does not have the resources for representing numerous epistemically relevant details in the unique situation in which testimony is given, many late 19th century thinkers like Venn turned away from the probabilistic analysis of testimony altogether. But a more nuanced approach using Bayes factors provides a better, more flexible, formalism for representing the evidential force of testimony.