A model to support collective reasoning: Formalization, analysis and computational assessment

TL;DR

This paper introduces a flexible model for representing human debates that allows for dynamic information addition, opinion expression, and analysis of collective reasoning without assuming rationality, supported by computational efficiency evaluations.

Contribution

It presents a novel debate model accommodating non-rational opinions and dynamic information, along with analysis of coherence and consensus effects on collective decision-making.

Findings

Aggregated opinions can be coherent despite low consensus.

The model supports efficient computation of collective opinions.

Different aggregation functions yield diverse coherence outcomes.

Abstract

Inspired by e-participation systems, in this paper we propose a new model to represent human debates and methods to obtain collective conclusions from them. This model overcomes drawbacks of existing approaches by allowing users to introduce new pieces of information into the discussion, to relate them to existing pieces, and also to express their opinion on the pieces proposed by other users. In addition, our model does not assume that users' opinions are rational in order to extract information from it, an assumption that significantly limits current approaches. Instead, we define a weaker notion of rationality that characterises coherent opinions, and we consider different scenarios based on the coherence of individual opinions and the level of consensus that users have on the debate structure. Considering these two factors, we analyse the outcomes of different opinion aggregation functions that compute a collective decision based on the individual opinions and the debate structure. In particular, we demonstrate that aggregated opinions can be coherent even if there is a lack of consensus and individual opinions are not coherent. We conclude our analysis with a computational evaluation demonstrating that collective opinions can be computed efficiently for real-sized debates.