Debate or Vote: Which Yields Better Decisions in Multi-Agent Large Language Models?

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Main Authors: Choi, Hyeong Kyu, Zhu, Xiaojin, Li, Sharon
Format: Preprint
Published: 2025
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author Choi, Hyeong Kyu
Zhu, Xiaojin
Li, Sharon
author_facet Choi, Hyeong Kyu
Zhu, Xiaojin
Li, Sharon
contents Multi-Agent Debate~(MAD) has emerged as a promising paradigm for improving the performance of large language models through collaborative reasoning. Despite recent advances, the key factors driving MAD's effectiveness remain unclear. In this work, we disentangle MAD into two key components--Majority Voting and inter-agent Debate--and assess their respective contributions. Through extensive experiments across seven NLP benchmarks, we find that Majority Voting alone accounts for most of the performance gains typically attributed to MAD. To explain this, we propose a theoretical framework that models debate as a stochastic process. We prove that it induces a martingale over agents' belief trajectories, implying that debate alone does not improve expected correctness. Guided by these insights, we demonstrate that targeted interventions, by biasing the belief update toward correction, can meaningfully enhance debate effectiveness. Overall, our findings suggest that while MAD has potential, simple ensembling methods remain strong and more reliable alternatives in many practical settings. Code is released in https://github.com/deeplearning-wisc/debate-or-vote.
format Preprint
id arxiv_https___arxiv_org_abs_2508_17536
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Debate or Vote: Which Yields Better Decisions in Multi-Agent Large Language Models?
Choi, Hyeong Kyu
Zhu, Xiaojin
Li, Sharon
Computation and Language
Multiagent Systems
Multi-Agent Debate~(MAD) has emerged as a promising paradigm for improving the performance of large language models through collaborative reasoning. Despite recent advances, the key factors driving MAD's effectiveness remain unclear. In this work, we disentangle MAD into two key components--Majority Voting and inter-agent Debate--and assess their respective contributions. Through extensive experiments across seven NLP benchmarks, we find that Majority Voting alone accounts for most of the performance gains typically attributed to MAD. To explain this, we propose a theoretical framework that models debate as a stochastic process. We prove that it induces a martingale over agents' belief trajectories, implying that debate alone does not improve expected correctness. Guided by these insights, we demonstrate that targeted interventions, by biasing the belief update toward correction, can meaningfully enhance debate effectiveness. Overall, our findings suggest that while MAD has potential, simple ensembling methods remain strong and more reliable alternatives in many practical settings. Code is released in https://github.com/deeplearning-wisc/debate-or-vote.
title Debate or Vote: Which Yields Better Decisions in Multi-Agent Large Language Models?
topic Computation and Language
Multiagent Systems
url https://arxiv.org/abs/2508.17536