Close Encounters with Arguments of the “Third Kind”:

Abstract

This paper presents a comparative analysis of argumentation models based on the concepts of subjective probability and plausible reasoning. This analysis makes explicit the “family resemblance” between subjective probability and plausible reasoning, while examining the differences in the requirements that each model invokes regarding the evaluation of three types of informal fallacies: argument from authority (ad verecundiam), appeal to popularity (ad populum) and begging the question (petitio principii). We conclude that plausible reasoning, as it is characterized by Rescher and Walton, does not provide a strong alternative to probability as a either a normative or descriptive model of argument evaluation.