Rational Irrationality
Version 1.0.0 · Updated 2026-07-28
CORE DEFINITION
Rational irrationality is an explanatory framework popularized by Bryan Caplan in 2001 and expanded in The Myth of the Rational Voter. If people prefer certain beliefs and the private marginal cost of holding mistaken beliefs is low, they may tolerate poor evidence and reasoning. “Rational” refers to instrumental pursuit of personal goals; “irrational” refers to departures from truth-seeking epistemic rationality. The theory does not require deliberately believing something known to be false.
SCAFFOLDING EFFECT
Reduce cognitive load
Distinguish lack of information from selective relaxation of evidential standards, and examine how identity, emotional satisfaction, and incentives to correct errors affect judgment. This is one possible explanation, not a basis for declaring disagreements false or labeling groups as irrational.
Anchor fast decisions
The theory proposes that preferences over beliefs and a low private marginal cost of error can reduce resistance to confirmation bias and emotional appeals. In a large election, for example, the low probability of one vote changing the result reduces the expected marginal benefit of correcting a policy judgment. This does not mean voters escape losses caused by policy. Rational ignorance concerns whether acquiring information is worthwhile; rational irrationality concerns how evidence is treated and beliefs are formed.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- en.wikipedia.orghttps://en.wikipedia.org/wiki/Rational_irrationalityverified
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