The Department of Logic & Philosophy of Science Colloquium Series presents

"A New Resolution of the Judy Benjamin Problem"
with Jan-Willem Romeijn, University of Groningen

October 21, 2011
3:00 p.m.
Social Science Tower, Room 777

About the talk:
In Van Fraassen's Judy Benjamin problem, the soldier Judy loses her way in the jungle. She contacts her base and a radio officer tells her that if she is in the territory of the Red army, the odds are three to one that she is in Headquarters area. How should she revise her beliefs in view of this conditional information? Van Fraassen's Judy Benjamin problem has generally been taken to show that not all rational changes of belief can be modelled in a probabilistic framework if the available update rules are restricted to Bayes's rule and Jeffrey's generalization thereof. But alternative rules based on distance functions between probability assignments that allegedly can handle the problem seem to have counterintuitive consequences. Taking a cue from a recent proposal by Richard Bradley, Romeijn argues that Jeffrey's rule can solve the Judy Benjamin problem after all. Moreover, Romeijn will show that the specific instance of Jeffrey's rule that solves the Judy Benjamin problem can be underpinned by a particular distance function. Finally, Romeijn's talk will extend the set of distance functions to ones that take into account the varying degrees to which propositions may be epistemically entrenched.

For further information, please contact Patty Jones, or 949-824-1520.


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