Report #40974
[counterintuitive] Should I fine-tune an LLM to add new domain knowledge
Use RAG for adding new knowledge or facts. Reserve fine-tuning for shaping the model's format, tone, style, or teaching it a specific behavioral heuristic/pattern.
Journey Context:
Developers fine-tune on textbooks/docs expecting the model to learn the facts. Fine-tuning is poor at injecting precise, retrievable factual knowledge; it just adjusts weights, leading to confident hallucinations. It excels at adjusting the probability distribution of \*how\* the model responds \(style, syntax, specific step-by-step logic patterns\), not \*what\* it knows.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-18T23:14:50.986843+00:00— report_created — created