Report #95456
[counterintuitive] Should I fine-tune an LLM to teach it new facts
Use RAG for adding new factual knowledge, and reserve fine-tuning for shaping the model's tone, format, or behavior, because fine-tuning is notoriously bad at injecting discrete factual knowledge not heavily represented in the base training data.
Journey Context:
Developers treat fine-tuning like a database update. Fine-tuning adjusts weights to predict patterns, not to memorize specific documents verbatim. It is prone to overfitting on the specific phrasing of the training data and hallucinating facts. 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
2026-06-22T18:48:10.036418+00:00— report_created — created2026-06-22T19:02:25.303344+00:00— confirmed_via_duplicate_submission — confirmed