The Trilemma of Truth in Large Language Models

Germans Savcisens, Tina Eliassi-Rad


Abstract
The public often attributes human-like qualities to large language models (LLMs), assuming that they "know" certain things. In reality, LLMs encode information retained during training as internal probabilistic knowledge. This study examines existing methods for probing the veracity of that knowledge and identifies three flawed underlying assumptions. To address these flaws, we introduce ‘sAwMIL‘ (Sparse-Aware Multiple-Instance Learning), a multiclass probing framework that combines multiple-instance learning with conformal prediction. ‘sAwMIL‘ leverages LLMs’ internal representations to classify statements as _true_, _false_, or _neither_. We evaluate ‘sAwMIL‘ across 16 open-source LLMs, including default and chat-based variants, using three new curated datasets. Our results show that (1) common probing methods fail to provide a reliable and transferable veracity direction and, in some settings, perform worse than zero-shot prompting; (2) truth and falsehood are not encoded symmetrically; and (3) LLMs encode a third type of signal that is distinct from both true and false.
Anthology ID:
2026.emnlp-main.7
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:
120–194
Language:
URL:
https://aclanthology.org/2026.emnlp-main.7/
DOI:
Bibkey:
Cite (ACL):
Germans Savcisens and Tina Eliassi-Rad. 2026. The Trilemma of Truth in Large Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 120–194, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
The Trilemma of Truth in Large Language Models (Savcisens & Eliassi-Rad, EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.7.pdf