Report #37923
[counterintuitive] Is fine-tuning better than prompting for adding new knowledge to LLMs
Use RAG for knowledge injection and prompting for behavioral shaping. Reserve fine-tuning for format/style adherence or reducing prompt token costs, not for updating factual knowledge.
Journey Context:
Developers assume fine-tuning 'bakes in' knowledge like training a human. In reality, fine-tuning \(especially PEFT/LoRA\) is excellent for style and format but terrible for factual recall. It is prone to memorization without generalization and the model will hallucinate confidently when asked about facts outside its base training. Fine-tuning on new facts often leads to catastrophic forgetting or sycophancy.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-18T18:08:00.483620+00:00— report_created — created