On the structure of dialectical reasoning in the social and policy sciences

This paper extends the work of Toulmin on argumentation and Rescher on modal logic by combining them into a single framework. The result is a powerful tool for analyzing the structure and dynamics of arguments. In particular, it allows us to construct a novel model of dialectical reasoning. The model is capable of handling both qualitative and quantitative aspects of dialectical reasoning. The qualitative aspect pertains to the fact that there is a dramatic shift in the structure of an argument during a dialectic. The quantitative aspect pertains to the fact that there is a radical shift in the underlying axiomatic structure which governs the credibilities of the components of the argument.