States of Knowledge and the Logic of Campaigning

Prof. Rohit Parikh (Distinguished Professor of Computer Science, Mathematics and Philosophy, City University of New York)

Info

Date	9th September 2008 (week , Michaelmas Term 2008)
Time	16:30
Place	Lecture Theatre A

Abstract

States of knowledge change when someone observes something or hears something. The simplest case of such a change arises when a public announcement is made, simultaneously changing the state of knowledge of all hearers; but even that case has some interesting applications. We give an account of Aumann's result on agreeing to disagree, some subsequent developments by Geanakoplos and Polemarchakis, and by Parikh and Krasucki.

A more interesting case arises when parties say something with an end in view. This converts a bare statement into a game theoretic move. This latter consideration leads to notions like Gricean implicature and cheap talk. We discuss this briefly and end up with a description of our model of how candidates running for election should (and do) speak. This last part is joint work with Walter Dean.