Current Issues in Conductive Argument Weight

Abstract

Carl Wellman’s seminal account of conductive premise weight is revisited, particularly with respect to his distinction between “automated” or “mechanical” scale weight and his concept of “heft” weight. I argue that Wellman’s concept of heft weight provides a suitable metaphor for premise weight in that both are non-numerically quantitative, comparative, and objective in the sense of intersubjective. Recent work in cognitive psychology is referenced as support for the concept of quantitative but non-numerical judgment in many aspects of human cognitive functioning. My interpretation of Wellman’s work provides a theoretical grounding for familiar the non-numerically quantitative categories of premise weight which are expressed in several different ways, e.g. “very strong, moderately strong, moderately weak, very weak, nil”, etc. I next proceed to apply the above interpretation of Wellman’s model to Trudy Govier’s account of conductive premise weight evaluation in terms of generalities and ceteris paribus clauses. Govier maintains that premise weight is proportional to the comparative quantity of exceptions that are made to the generality underlying each premise/consideration, with fewer exceptions implying greater conductive premise weight. In Govier’s widely studied ‘euthanasia example’, the comparative number of exception cases is understood in terms of prevailing social values underlying the opposing considerations. I argue for the existence of some parallels between Govier’s treatment of conductive evaluation in terms of exceptions cases and the role of social values in cased-based legal arguments in AI and Law. Trevor Bench-Capon and others in AI & Law have shown how cases are decided partly on the basis of values, with case decisions sometimes altering value rankings for future cases. Recent work by Robert C. Pinto in the informal logic approach has also, in my interpretation, shown interesting parallels with Bench-Capon’s work on cases and values. Emerging from the above analysis of Wellman, Govier, Bench-Capon, and Pinto is a strong suggestion that differences over individual premise weight can be rationally addressed through constructing an ‘argument to classification’ to one of the strength categories, at least for value-based conductive arguments. The existence in value-based argument and argumentation of deep disagreements does not, I argue, imply that premise weight is subjective in nature. A major implication of my findings is that the concept of argument weight in theory of argument is central and indeed essential in theory of argument. If so, conductive pro and con, issue-based argument and argumentation deserve an increasing level of attention within the theory of argument community.