Predictably Irrational
Also known as Predictably Irrational: The Hidden Forces That Shape Our Decisions
Dan Ariely's 2008 book on the systematic mistakes people make when they decide, and how to avoid them.
At a glance
Key ideas
Relativity, Anchoring, The cost of zero …
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- Ariely challenges the assumption that people make decisions by rational thought.
- Through experiments and anecdotes he shows that the mistakes are systematic, repeated again and again.
- Over 15 chapters he covers relativity, anchoring, the pull of "free", social and market norms, and more.
- He hopes that seeing the patterns will help readers avoid some of them.
Why it matters
- David Berreby, in The New York Times, called it "a far more revolutionary book than its unthreatening manner lets on".
Key facts
- Author
- Dan Ariely1
- Published
- 2008, by HarperCollins1
- Later edition
- Revised and expanded1
- Television
- Adapted as NBC's series The Irrational, which premiered on 25 Sep 20231
Key ideas
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Relativity1
People judge things against what is easy to compare, which is how a decoy option steers choices.
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Anchoring1
The first price people meet for something anchors what they will pay for it later.
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The cost of zero1
"When something is FREE! we forget the downside."
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Social and market norms1
Mixing favours with money can make people do less: lawyers refused to help retirees for about $30, but agreed to do it free.
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