@inproceedings{ranaldi-etal-2026-thinking,
    title = "Thinking in Schemas: Robust Syllogistic Reasoning in {LLM}s",
    author = "Ranaldi, Federico  and
      Ranaldi, Leonardo  and
      Zanzotto, Fabio Massimo  and
      Cohen, Shay B",
    editor = "Liakata, Maria  and
      Moreira, Viviane P.  and
      Zhang, Jiajun  and
      Jurgens, David",
    booktitle = "Proceedings of the 64th Annual Meeting of the {A}ssociation for {C}omputational {L}inguistics (Volume 1: Long Papers)",
    month = jul,
    year = "2026",
    address = "San Diego, California, United States",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/ingest-acl/2026.acl-long.1897/",
    pages = "40891--40909",
    ISBN = "979-8-89176-390-6",
    abstract = "LLMs often mistake what sounds true for what is formally valid. This limitation is especially evident in syllogistic reasoning, where plausible arguments can lead models to endorse conclusions that are logically invalid, a phenomenon known as Content Effect (CE).We present Boethius, a schema-guided framework for syllogistic reasoning that disentangles semantic plausibility from logical validity. Boethius adopts an auditable, quasi-formal reasoning process with two complementary stages: a Schema Module, which deduces the underlying logical form by analysing the formal structure of the premises, and an Instantiation Module, which instantiates this form over the concrete argument and evaluates validity independently of content-level semantics.Our results show that Boethius consistently outperforms existing approaches, improving syllogistic reasoning accuracy while substantially reducing CE. These gains hold for both large models in a pure in-context learning setting and smaller models trained via schema-guided trajectories using supervised fine-tuning and optimisation-based refinement."
}