The Fluency Heuristic

The fluency heuristic is the mind's habit of using processing ease as a signal of content validity. Information that goes down smoothly — easy-to-read fonts, familiar phrasing, well-structured prose — is judged as more true, more familiar, more trustworthy than the identical information presented less fluently. The heuristic evolved as a rough truth-detector: in natural environments, fluent processing correlated with genuine familiarity, and familiarity correlated with reliability. The correlation breaks catastrophically when a system can produce maximally fluent output on any topic regardless of the accuracy of the content. Claude speaks with identical fluency about topics where training data is deep and topics where it is sparse, about claims that are accurate and claims that are fabricated. The signal System 1 has relied on for hundreds of thousands of years has been severed, and nothing in the human cognitive architecture compensates.