Free-MAD: Consensus-Free Multi-Agent Debate

Yu Cui, Hang Fu, Haibin Zhang, Licheng Wang, Cong Zuo

Keywords: LLM, multi-agent system, consensus, robustness

Abstract: Multi-agent debate (MAD) is an emerging approach to improving the reasoning capabilities of large language models (LLMs). Existing MAD methods rely on multiple rounds of interaction among agents to reach consensus, and the final output is decided by majority voting in the last round. However, this consensus-based design faces several limitations. First, multiple rounds of communication increases token overhead and limits scalability. Second, due to the inherent conformity of LLMs, agents that initially produce correct responses may be influenced by incorrect ones during the debate process, causing error propagation. Third, majority voting introduces randomness and unfairness in the decision-making phase, and can degrade the reasoning performance. To address these issues, we propose Free-MAD, an alternative and novel MAD framework that eliminates the need for consensus among agents. Free-MAD introduces a novel score-based decision mechanism that evaluates the entire debate trajectory rather than relying on the last round only. This mechanism tracks how each agent's reasoning evolves, enabling more accurate and fair outcomes. In addition, Free-MAD reconstructs the debate phase by introducing anti-conformity, a mechanism that enables agents to mitigate excessive influence from the majority. Experiments on eight benchmark datasets demonstrate that Free-MAD significantly improves reasoning performance while requiring only a single-round debate and thus reducing token costs. We also show that compared to existing MAD approaches, Free-MAD exhibits improved robustness in real-world attack scenarios.

Primary Area: foundation or frontier models, including LLMs

Submission Number: 4775