Essays on Collective Decision-Making

Identifier:  TDX:2916

Handle: https://hdl.handle.net/20.500.11797/TDX2916

Authors:  Moskalenko, Anna

Abstract:
This thesis consists of four independent chapters related to collective decision-making. First, intra-party dynamics is analyzed in the presence of intra-party conflict. It is shown how the incorporation of intra-party democracy (in particular, the introduction of primaries) may help to resolve intra-party conflict. Second, the problem arising when a group of agents must choose a winner among themselves is studied. There exists a deserving winner, whom all agents know. Nevertheless, each agent is selfish: he always wants to be the winner. A veto mechanism is proposed that always chooses the deserving winner irrespective of the selfish preferences of the agents. Third, the assumption of the harmfulness of dictatorial voting rule is questioned. The aim is to get away from dictatorial voting rules, by searching for the rule that is the furthest away from the closest dictatorial rule, and to identify the rules balancing all dictatorial rules. The first result finds the reverse-plurality rule as the furthest from the closest dictatorial voting rule. Unfortunately, this rule violates some apparently desirable properties. The second result states that the plurality rule is the one that balances the agreement between all dictatorial voting rules. Fourth, the relationship between two incompatible properties of dictatorship and manipulability is analyzed, in terms of certain indices of manipulability and non-dictatorship. The aim is to shed some light on the problem of choosing between voting rules.