Conjunction of Evidence and Fuzzy Logic
Kevin M. Clermont
Cornell Law School
July 22, 2012
Cornell Legal Studies Research Paper No. 12-58
Classical logic and probability theory produce in law the troublesome conjunction paradox. The theories seem to tell us the conjoined likelihood of independent elements equals the product of each element’s likelihood. Meanwhile, the law requires each element of a cause of action to meet the standard of proof, but it does not apply the standard of proof to the conjunction. Hence, if the cause entails more than one element, no assurance exists that the product of likelihoods will meet the standard of proof.
Fuzzy logic, however, explodes the conjunction paradox. It does so by saying that the elements’ conjoined likelihood equals the least likely element’s likelihood. This is exactly equivalent to the law’s approach. That consistency constitutes a powerful piece of proof that the law employs fuzzy logic in preference to classical logic and probability theory.
Number of Pages in PDF File: 24
Keywords: Procedure, Standards of Proof, Logic, Probability
Date posted: July 22, 2012 ; Last revised: June 21, 2016