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Abstract: Nearly a decade ago, Dr. L. J. Cohen described a system of ordinal, inductive ‘probabilities' said to measure the strength of certain arguments. In The Role of Evidential Weight in Criminal Proof, Cohen argues that probabilities per se are insufficient to describe the probative force of evidence and that a calculus of ‘weight’ is required to supplement or supplant these probabilities. He asserts that one must attend to the completeness of the evidence used to estimate a probability, and that a measure of completeness cannot be incorporated into the probability itself or by means of another probability.
While agreeing that the fundamental premise requiring examination of the completeness of a body of evidence and the circumstances under which the evidence was gathered if one is to assess its probative value, this article disagrees with Cohen's conclusion that one is ‘inevitably driven’ to construct a model of forensic proof that relies on a conception of the ‘weight’ of a body of evidence that is logically distinct from the probability of an event conditioned on that body of evidence.
This article establishes that resort to a non-probabilistic measure of weight is unnecessary by giving an account of courtroom inference based strictly on probabilities and an interpretation of the burden of persuasion derived from decision theory.
Keywords: The Role of Evidential Weight in Criminal Proof, Probability, Evidence
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