Cross-lingual Self-Consistency for Multilingual Reasoning with Language Models

Ahmed Elhady, Eneko Agirre, Mikel Artetxe


Abstract
Despite expanding their multilingual coverage, the advanced reasoning capabilities of LLMs remain largely confined to a few high-resource languages like English. To address this, we propose an unsupervised Reinforcement Learning (RL) approach to enhance multilingual reasoning by enforcing cross-lingual self-consistency—the principle that a model should produce the same final answer for equivalent problems in different languages. Existing methods are limited by the scarcity of multilingual reasoning data, and show weak generalization to unseen languages. Our approach requires neither gold answers nor parallel data, and it achieves average gains of up to 21.7% on MGSM across 10 languages. In addition, our method demonstrates strong generalization, with an 18.2% mean improvement on MGSM languages unseen during training, and up to 6.2% gain on 3 out-of-distribution benchmarks. These results show the potential of consistency-based methods to improve the multilingual capabilities of LLMs without requiring supervised data.
Anthology ID:
2026.findings-emnlp.2042
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
43454–43466
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2042/
DOI:
Bibkey:
Cite (ACL):
Ahmed Elhady, Eneko Agirre, and Mikel Artetxe. 2026. Cross-lingual Self-Consistency for Multilingual Reasoning with Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 43454–43466, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Cross-lingual Self-Consistency for Multilingual Reasoning with Language Models (Elhady et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2042.pdf