A liberal paradox for judgment aggregation

Abstract

In the emerging literature on judgment (as opposed to preference) aggregation, expert rights or liberal rights have not been investigated yet. When a group forms collective beliefs, it may assign experts with special knowledge on certain propositions the right to determine the collective judgment on those propositions; and, when a group forms collective goals or desires, it may assign individuals specially affected by certain propositions similar rights on those propositions. We identify a problem similar to, but more general than, Sen's `liberal paradox': Under plausible conditions, the assignment of such rights to two or more individuals (or subgroups) is inconsistent with the unanimity principle, whereby propositions accepted by all individuals must be collectively accepted. So a group respecting expert or liberal rights on certain propositions must sometimes overrule its unanimous judgments on others. The inconsistency does not arise if either different individuals' rights are `disconnected' or individuals are `agnostic/tolerant' or `deferring/empathetic' towards other individuals' rights. Our findings have implications for the design of mechanisms by which groups (societies, committees, expert panels, organizations) can reach decisions on systems of interconnected propositions.liberal paradox, liberal right, expert right, subgroup rights, unanimity principle, judgment aggregation, empathy, deferral, tolerance, agnosticism