FLUENT IS NOT TRUE.
A LANGUAGE MODEL CONTINUES TEXT WITH WHAT IS LIKELY. LIKELY AND CORRECT USUALLY OVERLAP — NOT ALWAYS.

EVERY BRANCH SOUNDS RIGHT.
THICKER BRANCHES ARE MORE PROBABLE. NOTHING IN THE PROBABILITIES MARKS WHICH ONES ARE TRUE — ONLY A CHECK AGAINST A SOURCE CAN.
WHY IT HAPPENS

WHAT HELPS

Hallucination & Limits
Fluent Is Not True
NO SINGLE FIX REMOVES HALLUCINATION. STACK THE LAYERS — GROUNDING, CITATIONS, AN HONEST “I DON'T KNOW”, VERIFICATION — AND STILL CHECK WHAT MATTERS.
Four stacked filters — grounding, citations, an honest “I don't know”, verification — each with a few holes. Of four false claims falling through them, three are caught by the first three filters; one passes through holes that happen to line up and reaches the reader.