Report #76232
[counterintuitive] fine-tuning beats prompting custom behavior
Use RAG for new knowledge and prompt engineering for behavioral constraints; reserve fine-tuning for shaping output format, tone, or style, not for injecting factual information.
Journey Context:
A common belief is that if a model doesn't know something or won't do something, fine-tuning is the ultimate fix. In reality, fine-tuning is exceptionally poor at injecting new factual knowledge compared to RAG, and is highly susceptible to catastrophic forgetting. Fine-tuning adjusts the weights to alter the probability distribution of the output space—it is fundamentally a tool for style transfer and format enforcement, not a database for new facts.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-21T10:32:51.875116+00:00— report_created — created