The Present and Future of Judgement Aggregation Theory. A Law and Economics Perspective

Abstract

This chapter brie ‡y reviews the present state of judgment aggregation theory and tentatively suggests a future direction for that theory. In the review, we start by emphasizing the di¤erence between the doctrinal paradox and the discursive dilemma, two idealized examples which classically serve to motivate the theory, and then proceed to reconstruct it as a brand of logical theory, unlike in some other interpretations, using a single impossibility theorem as a key to its technical development. In the prospective part, having mentioned existing applications to social choice theory and computer science, which we do not discuss here, we consider a potential application to law and economics. This would be based on a deeper exploration of the doctrinal paradox and its relevance to the functioning of collegiate courts. On this topic, legal theorists have provided empirical observations and theoretical hints that judgment aggregation theorists would be in a position to clarify and further elaborate. As a general message, the chapter means to suggest that the future of judgment aggregation theory lies with its applications rather than its internal theoretical development.

The Semi-random Likelihood of Doctrinal Paradoxes

“…Doctrinal paradox is also a special case of responsibility voids, where no individual in the committee can morally be responsible voting outcome (Braham and VanHees 2011). List and Pettit (2002) proved the first impossible theorem about doctrinal paradox, which has lead to many followup impossibility theorems (Pauly and Hees 2006;Mongin 2008;Dietrich and List 2008;Awad et al 2017;Mongin 2019;Baharad, Neeman, and Rubinchik 2020;Marcoci and Nguyen 2020). Methods to escape from the paradox have been explored (Nehring and Pivato 2021;Rahwan and Tohmé 2010;Nehring and Puppe 2008;Lyon and Pacuit 2013).…”

“…The doctrinal paradox "originated the whole field of judgement aggregation" (Grossi and Pigozzi 2014), and continued to play a central role since then (List 2012;Grossi and Pigozzi 2014;Brandt et al 2016). A large body of literature has shown the negative effects of the doctrinal paradox in law (Kornhauser and Sager 1986;Hanna 2009;Chilton and Tingley 2012), economics (Mongin 2019), computational social choice (Bonnefon 2010;Brandt et al 2016), philosophy (Sorensen 2003;Mongin 2012) and psychology (Bonnefon 2011), etc. Unfortunately, the paradox is unavoidable under mild assumptions (List and Pettit 2002), and there is a large body of literature on impossibility theorems as well as ways for escaping from them (List and Polak 2010;Grossi and Pigozzi 2014;Endriss 2016).…”