Report #74916
[counterintuitive] Why does the LLM fail at simple logical deductions when the conclusion contradicts common sense even with step-by-step prompting
Do not rely on LLMs for strict symbolic logic or formal deduction without external verification. Use them for semantic reasoning and pair them with logic engines for strict rule adherence.
Journey Context:
The belief is that LLMs perform logical deduction. In reality, they perform semantic interpolation. When evaluating a premise, the model doesn't compute truth values in a symbolic logic space; it measures how 'close' the concepts are in its latent space. If a syllogism's conclusion is logically valid but semantically unlikely, the model will often deny the valid conclusion because the semantic distance between the concepts is vast. The architecture lacks a symbolic reasoning module.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-21T08:20:35.588499+00:00— report_created — created