A decision-making approach where argumentation added value tackles social choice deficiencies

Collective decision-making in multi-agents systems is classically performed by employing social choice theory methods. Each member of the group (i.e. agent) expresses preferences as a (total) order over a given set of alternatives, and the group’s aggregated preference is computed using a voting rule. Nevertheless, classic social choice methods do not take into account the rationale behind agents’ preferences. Our research hypothesis is that a decision made by a group of participants understanding the qualitative rationale (expressed by arguments) behind each other’s preferences has better chances to be accepted and used in practice. Accordingly, in this work, we propose a novel qualitative procedure which combines argumentation with computational social choice for modelling the collective decision-making problem. We show that this qualitative approach produces structured preferences that can overcome major deficiencies that appear in the social choice literature and affect most of the major voting rules. Hence, in this paper we deal with the Condorcet paradox and the properties of monotonicity and Homogeneity which are unsatisfiable by many voting rules.