BJPS Associate Editors don’t just act as midwives to great philosophy, they produce it too! Hot on the heels of ex-Associate Editor Marc Lange, Lara Buchak is featured in this year’s Philosopher’s Annual for her joint paper ‘Groupthink‘, written with Jeffrey Sanford Russell and John Hawthorn, and published in Philosophical Studies. Here’s the abstract:
How should a group with different opinions (but the same values) make decisions? In a Bayesian setting, the natural question is how to aggregate credences: how to use a single credence function to naturally represent a collection of different credence functions. An extension of the standard Dutch-book arguments that apply to individual decision-makers recommends that group credences should be updated by conditionalization. This imposes a constraint on what aggregation rules can be like. Taking conditionalization as a basic constraint, we gather lessons from the established work on credence aggregation, and extend this work with two new impossibility results. We then explore contrasting features of two kinds of rules that satisfy the constraints we articulate: one kind uses fixed prior credences, and the other uses geometric averaging, as opposed to arithmetic averaging. We also prove a new characterisation result for geometric averaging. Finally we consider applications to neighboring philosophical issues, including the epistemology of disagreement.