Humans and LLMs Diverge on Probabilistic Inferences

Gaurav Kamath, Sreenath Madathil, Sebastian Schuster, Marie-Catherine de Marneffe, Siva Reddy


Abstract
Human reasoning often involves working over limited information to arrive at probabilistic conclusions. In its simplest form, this involves making an inference that is not strictly entailed by a premise, but rather only likely given the premise. While reasoning LLMs have demonstrated strong performance on logical and mathematical tasks, their behavior on such open-ended, non-deterministic inferences remains largely unexplored. We introduce PROBCOPA, a dataset of 210 handcrafted probabilistic inferences in English, each annotated for inference likelihood by 25–30 human participants. We find that human responses are graded and varied, revealing probabilistic judgments of the inferences in our dataset. Comparing these judgments with responses from eight state-of-the-art reasoning LLMs, we show that models consistently fail to produce human-like distributions. Finally, analyzing LLM reasoning chains, we find evidence of a common reasoning pattern used to evaluate such inferences. Our findings reveal persistent differences between humans and LLMs, and underscore the need to evaluate reasoning beyond deterministic settings.1
Anthology ID:
2026.tacl-1.93
Volume:
Transactions of the Association for Computational Linguistics, Volume 14
Month:
Year:
2026
Address:
Cambridge, MA
Venue:
TACL
SIG:
Publisher:
MIT Press
Note:
Pages:
2057–2080
Language:
URL:
https://aclanthology.org/2026.tacl-1.93/
DOI:
10.1162/tacl.a.791
Bibkey:
Cite (ACL):
Gaurav Kamath, Sreenath Madathil, Sebastian Schuster, Marie-Catherine de Marneffe, and Siva Reddy. 2026. Humans and LLMs Diverge on Probabilistic Inferences. Transactions of the Association for Computational Linguistics, 14:2057–2080.
Cite (Informal):
Humans and LLMs Diverge on Probabilistic Inferences (Kamath et al., TACL 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.tacl-1.93.pdf