Philosophisches Seminar



Kolloquium Logik und Sprachtheorie

Einladung zum Vortrag

Prof. Dr. Erik C. W. Krabbe
(Universität Groningen)

Hamblin's and Lorenzen's Systems of Dialogue:
Comparison and Integration

Dienstag 18. Mai, 18 Uhr c.t.
WSI, Sand 14, Seminarraum A104

When Charles Hamblin introduced the notion of a formal dialectic, he did not refer to the dialogical logic of Paul Lorenzen and Kuno Lorenz. However, in hindsight the dialogue games of Lorenzen and Lorenz clearly present us with examples of a kind of formal dialectical systems avant la lettre. One may speak of Hamblin-type and of Lorenzen-type systems. How do these types compare? And can they be brought together?
After a short introduction about the concept of a formal dialectical system, this talk will focus on two exemplars, each of a different type: Hamblin’s Why–Because system with questions, also known as "System H", and a Lorenzen- type constructive propositional system, Constructive NOT-Dialectics (CND). We shall scrutinize Hamblin’s (unique) example of a dialogue in System H, and have a briefer look at a CND dialogue. Motivations for these systems as well as problematic aspects will be discussed. It will be obvious that "completeness" makes no sense for Hamblin-systems; but, as an excursion, we shall briefly delve into a method for obtaining relatively short completeness proofs for Lorenzen-type systems. Finally, we shall see how systems of these two types can be profitably integrated into one model of reasonable discussion.