Measuring Chain of Thought Faithfulness by Unlearning Reasoning Steps

Fuente: arXiv
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Autores principales: Tutek, Martin, Chaleshtori, Fateme Hashemi, Marasović, Ana, Belinkov, Yonatan
Formato: Preprint
Publicado: 2025
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author Tutek, Martin
Chaleshtori, Fateme Hashemi
Marasović, Ana
Belinkov, Yonatan
author_facet Tutek, Martin
Chaleshtori, Fateme Hashemi
Marasović, Ana
Belinkov, Yonatan
contents When prompted to think step-by-step, language models (LMs) produce a chain of thought (CoT), a sequence of reasoning steps that the model supposedly used to produce its prediction. Despite much work on CoT prompting, it is unclear if reasoning verbalized in a CoT is faithful to the models' parametric beliefs. We introduce a framework for measuring parametric faithfulness of generated reasoning, and propose Faithfulness by Unlearning Reasoning steps (FUR), an instance of this framework. FUR erases information contained in reasoning steps from model parameters, and measures faithfulness as the resulting effect on the model's prediction. Our experiments with four LMs and five multi-hop multi-choice question answering (MCQA) datasets show that FUR is frequently able to precisely change the underlying models' prediction for a given instance by unlearning key steps, indicating when a CoT is parametrically faithful. Further analysis shows that CoTs generated by models post-unlearning support different answers, hinting at a deeper effect of unlearning.
format Preprint
id arxiv_https___arxiv_org_abs_2502_14829
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measuring Chain of Thought Faithfulness by Unlearning Reasoning Steps
Tutek, Martin
Chaleshtori, Fateme Hashemi
Marasović, Ana
Belinkov, Yonatan
Computation and Language
When prompted to think step-by-step, language models (LMs) produce a chain of thought (CoT), a sequence of reasoning steps that the model supposedly used to produce its prediction. Despite much work on CoT prompting, it is unclear if reasoning verbalized in a CoT is faithful to the models' parametric beliefs. We introduce a framework for measuring parametric faithfulness of generated reasoning, and propose Faithfulness by Unlearning Reasoning steps (FUR), an instance of this framework. FUR erases information contained in reasoning steps from model parameters, and measures faithfulness as the resulting effect on the model's prediction. Our experiments with four LMs and five multi-hop multi-choice question answering (MCQA) datasets show that FUR is frequently able to precisely change the underlying models' prediction for a given instance by unlearning key steps, indicating when a CoT is parametrically faithful. Further analysis shows that CoTs generated by models post-unlearning support different answers, hinting at a deeper effect of unlearning.
title Measuring Chain of Thought Faithfulness by Unlearning Reasoning Steps
topic Computation and Language
url https://arxiv.org/abs/2502.14829