Propositional compositionality in neural language models

Jane Li, Abhinav Patil, Kyle Rawlins


Abstract
One of the most fundamental representations in linguistic semantics is that of the proposition (McGrath and Frank, 2005), standardly taken as the carrier of truth-conditions. Recent work shows that some form of truth can be decoded from language models (Azaria and Mitchell, 2023; Li et al., 2023), and strikingly, that for some models, truth is even represented linearly in intermediate layers (Marks and Tegmark, 2024, GoT). We take this line of work a step further and argue that neural language models can use propositional representations compositionally (Janssen 2010; Pickel and Szabó 2025 a.o.), drawing from evidence of the behaviour of logical connectives: the linear compositionality hypothesis. Specifically, we show (a) that the truth values of individual conjuncts can be decoded independently of the truth value of a complex conjunction, and (b) that we can causally intervene on individual conjuncts in a way that affects the truth value of the whole.
Anthology ID:
2026.scil-main.34
Volume:
Proceedings of the Society for Computation in Linguistics 2026
Month:
July
Year:
2026
Address:
San Diego, CA
Editors:
Rob Voigt, Alex Warstadt, Naomi Feldman, Tal Linzen
Venues:
SCiL | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
365–368
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.scil-main.34/
DOI:
Bibkey:
Cite (ACL):
Jane Li, Abhinav Patil, and Kyle Rawlins. 2026. Propositional compositionality in neural language models. In Proceedings of the Society for Computation in Linguistics 2026, pages 365–368, San Diego, CA. Association for Computational Linguistics.
Cite (Informal):
Propositional compositionality in neural language models (Li et al., SCiL 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.scil-main.34.pdf