arxivcs.CLcs.AI2026-07-09
Two Axes of LLM Abstention: Answer Correctness and Question Answerability
A model should refuse two different things: answers it would get wrong, and questions it should not answer at all, such as unanswerable ones or ones resting on a false premise. The usual recipe thresholds a single confidence score, which cannot tell these apart. Across five instr…