Day 18 of 150 Logic Difficulty 6/10
The Linda problem reveals the conjunction fallacy
Quick answer
The Linda problem reveals the conjunction fallacy. Today's question (Conjunction fallacy) asks about a finding from Tversky, A., & Kahneman, D. in 1983. The correct option is The conjunction rule, P(A∧B) ≤ P(A) — full explanation, primary source, and glossary cross-links below.
Today's question
In the "Linda problem," most participants rate "Linda is a bank teller and active in the feminist movement" as MORE probable than "Linda is a bank teller." This violates which axiom of probability?
Reveal the answer and explanation
Correct: C — The conjunction rule, P(A∧B) ≤ P(A)
Tversky & Kahneman (1983) showed that representativeness — how well Linda's description fits the feminist stereotype — overrides extensional logic. By definition, the joint probability of two events cannot exceed the probability of either event alone. Yet roughly 85% of participants commit the fallacy under fluent description. The conjunction effect is robust across statisticians, doctors, and intelligence analysts.
About the source
Tversky, A., & Kahneman, D. (1983). Extensional versus intuitive reasoning: The conjunction fallacy in probability judgment. Psychological Review, 90(4), 293–315.
Every Cognition Bible question cites a primary source — a paper, book chapter, or monograph that exists, that we can point to on Google Scholar, and whose finding the question accurately summarizes. No fabricated authority strings, no name-drops without paper-level grounding.
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