Why a vivid story can feel more likely
Picture a quiet, book-loving person. “She works in an office” may sound less convincing than “She is a librarian,” because the second description neatly matches a familiar image. The match makes the story feel plausible—but plausibility is not the same as probability.
The detail narrows the possibilities
A librarian can also work in an office, but librarians are only one group within the much larger set of office workers. So the probability that she is a librarian cannot exceed the probability that she works in an office. The more specific claim adds a requirement; it does not add people who fit.
The mistake is called the conjunction fallacy: judging a detailed combination of events or traits as more likely than a broader event that includes it. Here, the story’s personality details are treated as evidence for a narrow job description, even though they do not change how many people work in offices overall.
Why the intuition wins
People often use representativeness—a quick judgment about how closely someone resembles a familiar type—as a shortcut for estimating likelihood. A vivid, coherent description is easy to imagine, and that fluency can be mistaken for evidence. Meanwhile, the less vivid category, “office worker,” leaves many possibilities open and may feel like a poor fit simply because it says so little.
A useful check is to ask whether the specific scenario is contained within the broad one. If every librarian in the example would count as an office worker, but many office workers are not librarians, the broader description must be at least as likely. The story can fit beautifully and still describe a smaller slice of reality.
