Predictably Irrational
Predictably Irrational: The Hidden Forces That Shape Our Decisions is a 2008 book by behavioral economist Dan Ariely. It challenges the assumption that humans make rational decisions, showing instead that people consistently and predictably make irrational choices.
Key facts
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Author: Dan Ariely
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Published: 2008 (HarperCollins)
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Genre: Nonfiction, behavioral economics
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Subject: Irrationality, decision-making, cognitive biases
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ISBN: 978-0-06-135323-9
Themes and purpose
Ariely argues that human irrationality is systematic and predictable, not random. Through a series of ingenious experiments, he demonstrates how context, emotions, social norms, and expectations shape our choices in ways we don’t consciously recognize.
Structure and content
Each chapter examines a specific force that distorts decision-making: relativity, the decoy effect, the power of free, social vs. market norms, arousal, procrastination and self-control, ownership effects, and cheating. Ariely contrasts what rational economic theory predicts with what people actually do.
Reception and impact
A New York Times bestseller that popularized behavioral economics for a mass audience. Ariely’s accessible experiment-driven style made the field’s insights actionable. Critics noted some replication issues in later years but the book remains an influential introduction to predictable irrationality.