Formal and Empirical Research on Cascaded Inference in Jurisprudence

This paper reports observations from a series of formal and empirical studies of the process of assessing the probative value of evidence in the cascaded or hierarchical inference tasks commonly performed by fact finders in court trials. The formal research develops expressions that prescribe how the ingredients of various forms of evidence can be coherently combined in assessing the probative value of evidence. These expressions allow identification and systematic analysis of a wide assortment of subtle properties of evidence, many of which are commonly recognized in evidence law. The reported empirical research was designed to evaluate the consistency with which persons actually assess the probative value of evidence when they are asked to make these evaluations in several equivalent ways. Results show that persons, when required to mentally combine a large amount of probabilistic evidence, exhibit certain inconsistencies such as treating contradictory testimony as corroborative testimony and double-counting or overvaluing redundant testimony. However, when people are asked to make assessments about the fine-grained logical details of the same evidence, these inconsistencies do not occur.