Miscellaneous
Colloquium Mathematical Philosophy, Denis Bonnay (Paris Quest/IHPST) gives a talk at the MCMP Colloquium (30 April, 2015) titled "An Axiomatization of Individual and Social Updates". Abstract: In this talk, I will consider update rules, which an agent may follow in order to update her subjective probabilities and take into account new information she receives. I will consider two different situations in which this may happen: (1) individual updates: when an agent learns the probability for a particular event to have a certain value. (2) social updates: when an agent learns the probability an other agent's gives to a particular event. Jeffrey's conditioning and weighted averaging are two famous update rules, in individual and social situations respectively. I will show that both can be axiomatized by means of one and the same invariance principle, related to Carnap's use of invariance in his work on probabilities.