Ill-informed Consensus or Truthful Disagreement? How Argumentation Styles and Preference Perceptions Affect Deliberation Outcomes in Groups with Conflicting Stakes

In groups where members deliberate with limited information, consensus can emerge where, under complete information, fundamental disagreement would prevail. Using an agent-based model, we explore the factors contributing to group consensus by comparing argumentation styles in two types of groups: agents in groups of advocates communicate arguments for options perceived as personally beneficial. Agents in groups of diplomats do the same but avoid disagreement in that they bring up arguments supporting a second-best option whenever their interaction partner perceives to benefit the least from what the sender finds best. Results show that consensus depends on argumentation style, but also on what members initially perceive as preferred. Diplomats are more likely to form consensus when initial perceptions accurately align with full information preferences, which diverge within the group. Conversely, and perhaps counterintuitively, in the presence of inaccurate initial perceptions, groups of advocates converge while diplomats part in disagreement. Our results imply that the ideal argumentation style must be considered carefully in light of both the desired outcome and the initial information distribution: when conflicting stakes produce a trade-off between consensus and truthful perceptions, polite versus selfish ways of deliberation may produce one or the other outcome, depending on the initial information members are equipped with.