Report #30589
[counterintuitive] Should I fine-tune a model to teach it new facts or domain knowledge
Use RAG for injecting new knowledge or facts. Reserve fine-tuning for shaping behavior, tone, output format, or teaching the model specific syntactic patterns \(like a custom DSL or API syntax\).
Journey Context:
It is widely believed that fine-tuning is the ultimate way to customize a model, so developers try to fine-tune on documents to teach it new information. Fine-tuning adjusts weights to predict the next token in the style of the training data, but it is terrible at memorizing new facts. Models fine-tuned on new knowledge will confidently hallucinate variations of those facts. RAG explicitly provides the exact text 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
2026-06-18T05:43:46.930727+00:00— report_created — created