Olle Häggström: Fundamentals of Bayesian reasoning and the choice of prior

Abstract: Bayesian reasoning goes far beyond just Bayesian statistics, and is influential, e.g., in economics and in computer science. There is a beautiful body of work, going back to 20th century thinkers including Ramsey, de Finetti, von Neumann, Morgenstern and Savage, that is often taken as an indication that rationality implies Bayesian reasoning. In a recent Ph.D. course we centred around the question of how convincing this conclusion is, and arrived tentatively at an answer along the lines of "well, maybe sort of...". In this talk I will recap some of these discussions, and also address the issue of whether a prior can be chosen in a way that avoids arbitrariness and subjectivity.