Fallacy · Bad evidence
Conjunction fallacy
Also called: The Linda problem
Judging a detailed story as more likely than a simpler one it contains.
What it is
Every added detail is another thing that has to be true, so a story can only become less likely as it grows. Yet detailed stories feel more believable, because they fit together. The more specific a prediction, the more ways it can turn out wrong.
An example
Linda studied philosophy and campaigned for social justice. Which is more likely: “Linda is a bank teller” or “Linda is a bank teller and active in the feminist movement”? Most people pick the second, but it cannot be more likely than the first.
How to spot it
A detailed scenario seems convincing because the pieces fit, not because each piece is likely.
How to answer it
“Each detail has to be true as well. Does adding it really make the story likelier?”
When it is not a fallacy
A detailed story can be the right bet when the choice is between two detailed stories, or when every detail is well supported. The error is ranking a story above a plainer one it contains.
Printable sheet of all fallacies
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A plain reference you can paste into notes or an essay:
Quest2Reason. “Conjunction fallacy.” https://quest2reason.com/learn/ideas/fallacies/conjunction-fallacy. Accessed 13 November 2026.