Definition
False belief that a conjunction of two events is more probable than one of the two events on its own
The longer version of the experiment separated the two critical elements with an intermediate element, so readers would treat every element as separated. In the shorter version there was a direct comparison between the two critical elements so most of the readers with statistics knowledge would not fall in the fallacy.
See also
- Sistema 1 è automatico e veloce, sistema 2 è lento, deliberato e richiede attenzione — the conjunction fallacy is a Sistema 1 error: representativeness (how well B fits the description) overrides probability rules that require Sistema 2
- Narrative Fallacy makes us explain the past through cause-and-effect — the conjunction feels more probable because it tells a better story; narrative coherence hijacks probabilistic reasoning
- Misjudging Reliability and Causality — same family: we substitute a question about probability with a question about narrative fit, then treat the narrative answer as probabilistic truth
- Non possiamo eliminare i bias, possiamo solo riconoscere le situazioni a rischio — the fallacy disappears in direct comparison conditions; this is the practical mitigation: force explicit comparison rather than independent evaluation