Cognitive Scaffold

Preparing your thinking workspace

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MENTAL MODEL · M4004

Barber Paradox

Barber Paradox
StructureHigh supportLogic
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Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

A logical paradox proposed by Russell: a barber shaves all and only those men who do not shave themselves. Does he shave himself? Both yes and no answers lead to contradiction, revealing the logical dilemma of self-reference.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Identifying self-reference traps. In rule design, system architecture, and policy-making, be wary of definitions or rules that involve self-reference. Helps identify and avoid system designs that seem reasonable but are internally contradictory.

anchor

Anchor fast decisions

In a town, the barber shaves all and only those men who do not shave themselves. The question of whether he shaves himself constitutes a self-referential contradiction. It is a popular version of Russell's paradox, exposing the flaw in naive set theory.

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Source support: Explicit

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    zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E7%90%86%E5%8F%91%E5%B8%88%E6%82%96%E8%AE%BAZH · Explicit
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