The Mirage of Explainability: A Survey on Chain-of-Thought Faithfulness in Large Language Models

Xi Jin, LeChen Qi, Houfeng Wang, Liangming Pan


Abstract
Chain-of-Thought (CoT) reasoning appears to provide explainability, leading users to trust that verbalized rationales reflect the model’s underlying computation. However, substantial evidence indicates that CoT often fails to reflect the model’s actual decision-making process, leading to a surge of research into the faithfulness of these explanations. This paper presents a comprehensive survey of CoT faithfulness. We first unify the definition of faithfulness by integrating internal alignment with external consistency and synthesize key failure phenomena, such as post-hoc rationalization and sycophancy. Furthermore, we systematize evaluation metrics, benchmarks, and critically review current mitigation strategies. We conclude by outlining open challenges and advocating for architectural innovations to achieve genuinely faithful reasoning for credible AI.
Anthology ID:
2026.emnlp-main.614
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
14122–14136
Language:
URL:
https://aclanthology.org/2026.emnlp-main.614/
DOI:
Bibkey:
Cite (ACL):
Xi Jin, LeChen Qi, Houfeng Wang, and Liangming Pan. 2026. The Mirage of Explainability: A Survey on Chain-of-Thought Faithfulness in Large Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 14122–14136, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
The Mirage of Explainability: A Survey on Chain-of-Thought Faithfulness in Large Language Models (Jin et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.614.pdf