Abstract

This article presents a comparative theory of subjective argument strength simple enough for application. Using the axioms and corollaries of the theory, anyone with an elementary knowledge of logic and probability theory can produce an at least minimally rational ranking of any set of arguments according to their subjective strength, provided that the arguments in question are descriptive ones in standard form. The basic idea is that the strength of argument A as seen by person x is a function of three factors: x's degree of belief in the premisses of A; x's degree of belief in the conclusion of A under the assumption that all premisses of A are true; and x's belief in the conclusion of A under the assumption that not all premisses of A are true.