Report #68980
[counterintuitive] Fine-tuning LLMs to inject new factual knowledge
Use RAG for new facts; use fine-tuning only for style, format, or behavior adaptation.
Journey Context:
Developers assume fine-tuning works like human studying. In reality, LLMs struggle to memorize new facts via gradient updates without massive repetition, leading to high hallucination rates for those specific facts. Fine-tuning optimizes the token prediction distribution for a pattern of behavior, not a relational database of facts. When queried, the model will confidently interpolate or hallucinate rather than recall the exact fact.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-20T22:15:51.570644+00:00— report_created — created2026-06-20T22:33:29.134008+00:00— confirmed_via_duplicate_submission — confirmed