# Rule 2: Empirical Evidence & Logging

- **Mandatory Logging**: If an issue occurs and there are no logs (or insufficient logs) to diagnose it, you must STOP immediately and add logging.
- **Replication**: After adding logging, you must repeat the test to replicate the exact issue so that the logs capture the failure.
- **No Blind Changes**: NO business logic can be altered blindly or based on guesses. You must have empirical evidence (derived from the logs) proving the root cause before attempting any changes to the logic.