Ultrafilters arise frequently in the social choice literature and surrounding fields as collections of the decisive set for a given aggregation procedure. We know from [8] that we can associate each Arrow social welfare function with an ultrafilter. Because of their structure, ultrafilters are useful in analyses of both finite and infinite voting populations. For an infinite set of voters, [5] ...

The aggregation of consistent individual judgments on logically interconnected propositions into a collective judgment on those propositions has recently drawn much attention. Seemingly reasonable aggregation procedures, such as propositionwise majority voting, cannot ensure an equally consistent collective conclusion. In this paper, we motivate that quite often, we do not only want to make a f...

In abstract argumentation, where arguments are viewed as abstract entities with a binary defeat relation among them, a set of agents may assign individual members the right to determine the collective defeat relation on some pairs of arguments. I prove that even under a minimal condition of rationality, the assignment of rights to two or more agents is inconsistent with the unanimity principle,...

ii ACKNOWLEDGEMENTS I would like to express my gratitude to Fulbright–LASPAU, the scholarship program that made my studies in the United States possible. I would also like to thank my thesis advisor, Dr. Michael E. Shin, for his great patience, trust, and support. I am grateful to my parents for their endless love and support. Finally, I want to express my gratitude to all the friends and colle...

The fact that a judge can make a discretion on a case has currently acquired recognition. This article is going to make a discussion on employment of the method of balancing of interests by a judge under the active judicial background. It mainly discusses the following several issues: whether a judge should choose a standard inside the law or seek for a standard for judgment outside the law whe...

One of the better studied properties for operators in judgment aggregation is independence, which essentially dictates that the collective judgment on one issue should not depend on the individual judgments given on some other issue(s) in the same agenda. Independence is a desirable property for various reasons, but unfortunately it is too strong, as, together with mild additional conditions, i...

The problem of the aggregation of consistent individual judgments on logically interconnected propositions into a collective judgment on the same propositions has recently drawn much attention. The difficulty lies in the fact that a seemingly reasonable aggregation procedure, such as propositionwise majority voting, cannot ensure an equally consistent collective outcome. The literature on judgm...

This paper introduces a new class of judgment aggregation rules, to be called ‘scoring rules’ after their famous counterparts in preference aggregation theory. A scoring rule generates the collective judgment set which reaches the highest total ‘score’across the individuals, subject to the judgment set having to be rational. Depending on how we de…ne ‘scores’, we obtain several (old and new) so...