Swinburne's Challenge: A Note on Probability Estimates for Nontypical Potential Evidence Instances

General confirmation theory, and especially its Bayesian variant, has never been able to adequately address the issue of how to handle qualitative evidence instances. Such statements encompass a wide class including historical claims, those of the human sciences not incorporating quantitative models, legal statements and the like. The issue was recognized by the philosopher Swinburne (1973) who puzzled how such statements as, Caesar crossed the Rubicon, could be assigned a meaningful probability estimate. The present paper suggests that such statements can be transformed into, at least, plausible probability estimates. This requires a two step process: judgements made by credible raters, and the transformation of judgements into one or more reliability co-efficients. These reliability estimates can then be utilized in the standard Bayesian model to yield plausible degrees of belief between hypothesis and evidence.