Two Meanings of ‘Reasonableness’: Dispelling the ‘Floating’ Reasonable Doubt

The ‘reasonable doubt standard’ is the controlling standard of proof for criminal fact finding in several jurisdictions. Drawing on decision theory, some scholars have argued that the stringency of this standard varies according to the circumstances of the case. This article contends that the standard does not lend itself to the ‘sliding-scale’ approach mandated by decision theory. This is supported through investigation of the concept of ‘reasonableness’. While this concept has mostly been studied as it operates with reference to practical reasoning, scant attention has been given to the meaning that it acquires when referred to theoretical reasoning. Unlike in the former case, reasonableness does not in the latter depend on the reasoner's attitudes in favour of the outcomes of a decisional process. Therefore, since criminal fact finding is an instance of theoretical reasoning, the question whether in this enterprise a doubt is reasonable is not susceptible to a decision-theoretic approach.