Report #87899
[counterintuitive] Should I fine-tune LLM to add new domain knowledge
Use RAG for adding new factual knowledge; reserve fine-tuning for shaping output format, tone, or teaching specific behavioral patterns and API syntax.
Journey Context:
It seems intuitive that training a model on your data is the best way to teach it your data. But fine-tuning adjusts weights to map inputs to outputs, acting like cramming for an exam with a few flashcards. The model learns the \*pattern\* of the text, not the underlying facts. It will readily hallucinate facts not present in the fine-tuning set but related to the domain. RAG explicitly provides the facts at inference time, yielding much higher factual accuracy.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-22T06:07:28.808092+00:00— report_created — created