What probabilistic means in practice
An LLM-based system books your flight and hands you a boarding pass. You show up at the airport. The flight doesn’t exist. The LLM didn’t fail to act — it hallucinated a completed task, with full confidence.
Ask the same system to book New York, ten times. Nine times it works. Once, you get San Francisco. No error. No warning. No way to predict when it will happen next.
This is what probabilistic means in practice. Not a theoretical concern — a structural one. The model isn’t broken. It’s working exactly as designed. It’s just not designed to be reliable.