Morables: A Benchmark for Assessing Abstract Moral Reasoning in LLMs with Fables
Matteo Marcuzzo, Alessandro Zangari, Andrea Albarelli, Jose Camacho-Collados, Mohammad Taher Pilehvar
Abstract
As LLMs excel on standard reading comprehension benchmarks, attention is shifting toward evaluating their capacity for complex abstract reasoning and inference. Literature-based benchmarks, with their rich narrative and moral depth, provide a compelling framework for evaluating such deeper comprehension skills. Here, we present Morables, a human-verified benchmark built from fables and short stories drawn from historical literature. The main task is structured as multiple-choice questions targeting moral inference, with carefully crafted distractors that challenge models to go beyond shallow, extractive question answering. To further stress-test model robustness, we introduce adversarial variants designed to surface LLM vulnerabilities and shortcuts due to issues such as data contamination. Our findings show that, while larger models outperform smaller ones, they remain susceptible to adversarial manipulation and often rely on superficial patterns rather than true moral reasoning. This brittleness results in significant self-contradiction, with the best models refuting their own answers in roughly 20% of cases depending on the framing of the moral choice. Interestingly, reasoning-enhanced models fail to bridge this gap, suggesting that scale - not reasoning ability - is the primary driver of performance.- Anthology ID:
- 2025.emnlp-main.1411
- Volume:
- Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
- Month:
- November
- Year:
- 2025
- Address:
- Suzhou, China
- Editors:
- Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
- Venue:
- EMNLP
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 27715–27739
- Language:
- URL:
- https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1411/
- DOI:
- Cite (ACL):
- Matteo Marcuzzo, Alessandro Zangari, Andrea Albarelli, Jose Camacho-Collados, and Mohammad Taher Pilehvar. 2025. Morables: A Benchmark for Assessing Abstract Moral Reasoning in LLMs with Fables. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 27715–27739, Suzhou, China. Association for Computational Linguistics.
- Cite (Informal):
- Morables: A Benchmark for Assessing Abstract Moral Reasoning in LLMs with Fables (Marcuzzo et al., EMNLP 2025)
- PDF:
- https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1411.pdf