Date of Original Version
Proceedings of the Fourth International Symposium on Imprecise Probabilities and Their Applications. Pittsburgh, PA. 2005.
Abstract or Table of Contents
The "Ellsberg phenomenon" has played a significant role in research on imprecise probabilities. Fox and Tversky  have attempted to explain this phenomenon in terms of their "comparative ignorance" hypothesis. We challenge that explanation and present empirical work suggesting an explanation that is much closer to Ellsberg's own diagnosis.