15 - Linda Less is More

Описание: The famous Linda paradox reveals the conjunction fallacy: we believe a more detailed story is more probable, even though logically it is less probable. The chapter explains how System 1 loves coherent narratives and how System 2 fails to detect simple logical errors.

Kahneman presents one of the most famous examples in cognitive psychology: the Linda problem. Participants read a description of Linda as a 31-year-old woman who is single, outspoken, very bright, majored in philosophy, was deeply concerned with discrimination and social justice, and participated in anti-nuclear demonstrations. They were then asked which statement is more probable: "Linda is a bank teller" or "Linda is a bank teller and is active in the feminist movement."

The chapter reveals a striking finding: about 85-90% of people, including statistically sophisticated participants, judge that "Linda is a bank teller and is active in the feminist movement" is more probable than "Linda is a bank teller." This violates a fundamental rule of logic: a conjunction (A and B) cannot be more probable than either of its constituents (A alone or B alone). The set of feminist bank tellers is wholly included in the set of bank tellers, so it must be smaller or at most equal in size.

Kahneman explains that people commit the conjunction fallacy because they substitute probability with representativeness and plausibility. Linda's description strongly suggests feminist activism, making "feminist bank teller" more representative of Linda than just "bank teller." System 1 generates an impression of coherence and plausibility, which System 2 accepts without checking against logical rules. The compelling narrative overwhelms statistical logic.

The chapter distinguishes between two types of thinking: System 1 thinking (which assesses coherence and representativeness) and System 2 thinking (which should apply logical and statistical rules). The Linda problem demonstrates that even when System 2 is engaged, it often fails to detect violations of logical rules when they conflict with compelling intuitive impressions. Most people sense that something is odd about ranking "bank teller" as less probable than "feminist bank teller," but they cannot identify the logical error.

Kahneman shows that the conjunction fallacy is robust and difficult to eliminate. Even when participants are told about the conjunction rule before judging, many still commit the fallacy. Phrasing the question in terms of frequencies rather than probabilities reduces but does not eliminate the error. The power of representativeness and narrative coherence is so strong that it regularly defeats logic.

The practical implications extend beyond psychology experiments: business plans with detailed scenarios seem more probable than simpler outcomes; medical diagnoses with elaborate symptom patterns feel more certain than general diagnoses; and political forecasts with rich narratives appear more credible than statistical predictions. The chapter teaches a crucial lesson: more detailed descriptions and more elaborate scenarios are less probable, not more probable. When evaluating probability, less detail means more likelihood. The key is to recognize when your judgment is based on plausibility and representativeness rather than probability, and to apply the basic logic: a conjunction can never be more probable than its constituents.