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Main Authors: Xu, Tianrun, Jing, Haoda, Li, Ye, Wei, Yuquan, Feng, Jun, Chen, Guanyu, Gao, Haichuan, Zhang, Tianren, Chen, Feng
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.20912
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author Xu, Tianrun
Jing, Haoda
Li, Ye
Wei, Yuquan
Feng, Jun
Chen, Guanyu
Gao, Haichuan
Zhang, Tianren
Chen, Feng
author_facet Xu, Tianrun
Jing, Haoda
Li, Ye
Wei, Yuquan
Feng, Jun
Chen, Guanyu
Gao, Haichuan
Zhang, Tianren
Chen, Feng
contents Recent advances in multimodal language models (MLLMs) have made thinking with images a dominant paradigm for multimodal reasoning. However, existing methods still fail to ensure evidence-answer consistency, where correct answers must be supported by correct visual evidence. To address this issue, we propose DeFacto, a counterfactual reasoning framework that explicitly aligns visual evidence with final answers. Our approach integrates three complementary training paradigms: positive, counterfactual, and random-masking. We further develop a language-guided evidence construction pipeline that automatically localizes question-relevant regions and generates counterfactual variants, resulting in DeFacto-100K. Building on this dataset, we train MLLMs with GRPO-based reinforcement learning and design three complementary rewards to promote correct answering, structured reasoning, and consistent evidence selection. Moreover, we introduce DeFacto-1.5K, a human-annotated benchmark for systematically evaluating evidence-grounded consistency beyond answer accuracy. Experiments on diverse benchmarks demonstrate that DeFacto substantially improves both answer accuracy and evidence-answer consistency over strong baselines.
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publishDate 2025
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spellingShingle DeFacto: Counterfactual Thinking with Images for Enforcing Evidence-Grounded and Faithful Reasoning
Xu, Tianrun
Jing, Haoda
Li, Ye
Wei, Yuquan
Feng, Jun
Chen, Guanyu
Gao, Haichuan
Zhang, Tianren
Chen, Feng
Artificial Intelligence
Recent advances in multimodal language models (MLLMs) have made thinking with images a dominant paradigm for multimodal reasoning. However, existing methods still fail to ensure evidence-answer consistency, where correct answers must be supported by correct visual evidence. To address this issue, we propose DeFacto, a counterfactual reasoning framework that explicitly aligns visual evidence with final answers. Our approach integrates three complementary training paradigms: positive, counterfactual, and random-masking. We further develop a language-guided evidence construction pipeline that automatically localizes question-relevant regions and generates counterfactual variants, resulting in DeFacto-100K. Building on this dataset, we train MLLMs with GRPO-based reinforcement learning and design three complementary rewards to promote correct answering, structured reasoning, and consistent evidence selection. Moreover, we introduce DeFacto-1.5K, a human-annotated benchmark for systematically evaluating evidence-grounded consistency beyond answer accuracy. Experiments on diverse benchmarks demonstrate that DeFacto substantially improves both answer accuracy and evidence-answer consistency over strong baselines.
title DeFacto: Counterfactual Thinking with Images for Enforcing Evidence-Grounded and Faithful Reasoning
topic Artificial Intelligence
url https://arxiv.org/abs/2509.20912