Matthias Unterhuber (Düsseldorf) gives a talk at the MCMP Colloquium (12 Jan, 2012) titled "Modeling AGM Belief Revision by Possible Worlds Semantics: The Case of Chellas-Segerberg Semantics". Abstract: Both AGM belief revision and conditional logics use the Ramsey test to spell out how to evaluate (indicative) conditionals. In AGM belief revision the Ramsey test is specified on the basis of belief revision operations. In my talk I will take the reverse approach and explore in how far a conditional logic interpretation of possible worlds semantics with the Ramsey test can model belief revision. For that purpose I will use the Chellas-Segerberg semantics, which does not presuppose orderings of possible worlds, but allows - as I argue in my PhD thesis - for a plausible interpretation of conditionals in terms of a qualitative Ramsey test. My approach contrasts with possible worlds accounts of AGM belief revision in the literature, which either employ a Lewis' type sphere semantics (e.g., Grove, Segerberg) or else a temporal logic semantics (e.g., Bonanno).

Matthias Unterhuber is a post-doctoral research fellow at the chair of theoretical philosophy (Gerhard Schurz) in Duesseldorf. He recently completed his PhD on possible worlds semantics for conditionals. His interests include conditional logic, modal logic, belief revision, Bayesianism, human reasoning, prototype theory and causality.