We are pleased to announce that Paul Weirich, Curators’ Professor of the Department of Philosophy at the University of Missouri-Columbia, will deliver a Games and Decisions lecture, “Decisions without Sharp Probabilities,” on Wednesday, February 22, 2012, at Carnegie Mellon University. Weirich, having earned a B.A. in philosophy from Saint Louis University, pursed a doctorate in philosophy at the University of California, Los Angeles, earning a Ph.D. in 1977 for his thesis, Probability and Utility for Decision Theory, written under the supervision of Tyler Burge. In addition to numerous articles, Weirich is author of Collective Rationality: Equilibrium in Cooperative Games (OUP: 2010), Realistic Decision Theory: Rules for Nonideal Agents in Nonideal Circumstances (OUP: 2004), Decision Space: Multidimensional Utility Analysis (CUP: 2001), and Equilibrium and Rationality: Game Theory Revised by Decision Rules (CUP: 1998). What follows is an abstract of his Games and Decisions lecture.
Adam Elga (2010) argues that no principle of rationality leads from unsharp probabilities to decisions. He concludes that a perfectly rational agent does not have unsharp probabilities. This paper defends unsharp probabilities. It shows how unsharp probabilities may ground rational decisions.
Unsharp probabilities arise from sparse or unspecific evidence. For example, meteorological evidence, because unspecific, often does not suggest a sharp probability that tomorrow will bring rain. An agent may assign to rain a range of probabilities going from, say, 0.4 to 0.6. Elga argues that unsharp probability assignments may lead an agent to a sure loss. In this event, a dilemma arises: the agent may have either unsharp probability assignments that accurately represent evidence, or sharp probabilities that prevent sure losses. Should an agent’s probability assignments be faithful to the evidence, or should they promote practical success? This paper maintains that an agent’s probability assignments can attain both goals.
Games and Decisions Group
Department of Philosophy
Carnegie Mellon University
Wednesday, February 22, 2012
12:30-1:30 pm Baker Hall 135
As usual, all are invited to attend. To ensure that we can accommodate all lunchtime guests, please contact Teddy Seidenfeld or Kevin Zollman to signal your intention to attend.
Posted by Arthur Paul Pedersen 
Jonah N. Schupbach
Horacio Arló-Costa
Jeff Helzner
Gregory Wheeler
Jon Williamson
Vincenzo Crupi
Jake Chandler
Arthur Paul Pedersen
Sonja Smets
Carlo Martini
