Report #51415
[counterintuitive] Should I fine-tune an LLM to teach it new facts
Use RAG for adding new knowledge or facts. Reserve fine-tuning for shaping the model's format, tone, or behavioral patterns \(e.g., outputting specific JSON schemas, learning a new coding style\).
Journey Context:
Developers conflate 'custom behavior' with 'custom knowledge.' Fine-tuning is excellent for teaching the model \*how\* to behave \(style, format\) but terrible for teaching it \*what\* to know. Fine-tuning on new facts leads to high hallucination rates because the model interpolates the new data into its existing weights without robust retrieval mechanisms. RAG explicitly separates knowledge from reasoning, allowing for updates without retraining.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-19T16:47:05.416721+00:00— report_created — created