How We Know What Isn’t So
How We Know What Isn’t So: The Fallibility of Human Reason in Everyday Life is a 1991 book by psychologist Thomas Gilovich. It explores the psychological mechanisms behind why people form and hold onto false beliefs.
Key facts
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Author: Thomas Gilovich
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Published: 1991 (Free Press)
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Genre: Nonfiction, psychology
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Subject: Cognitive biases, belief formation, statistical reasoning
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ISBN: 978-0-02-911706-4
Themes and purpose
Gilovich examines how cognitive biases, social influences, and misinterpretation of random data lead people to believe things that aren’t true. He covers illusions of pattern perception, biases in interpreting incomplete data, and the social forces that reinforce erroneous beliefs.
Structure and content
The book is organized into three parts: cognitive determinants of questionable beliefs (pattern perception, stereotyping), social determinants (misinformation, peer influence), and the appeal of erroneous beliefs in everyday life. Each chapter uses real-world examples from sports, finance, medicine, and paranormal claims.
Reception and impact
A foundational text in the cognitive biases and skepticism literature, widely cited in behavioral economics and social psychology. Gilovich’s work laid groundwork for later popular treatments of irrationality by Kahneman, Ariely, and others.