Information Update as Social Choice Johan van Benthem Abstract: Information update and the resulting belief revision may be viewed as a process of merging plausibility or preference relations coming from different sources. In this note, first presented at the Dynamic Logic Workshop in Montréal June 2007, we show how 'priority product update' in the sense of Baltag & Smets can be characterized precisely in terms of reasonable postulates of 'social choice' between such sources. The result uses ideas from Andréka, Ryan & Schobbens on preference merge, and our somewhat radical view here is that agents are dynamic societies consisting of all inputs they received over time. Keywords: dynamic epistemic logic; product update; preference merge; social choice