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How We Know What Isn't So: The Fallibility of Human Reason in Everyday Life
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How We Know What Isn't So: The Fallibility of Human Reason in Everyday Life

3.96  ·  Rating details ·  2,946 ratings  ·  121 reviews
Thomas Gilovich offers a wise and readable guide to the fallacy of the obvious in everyday life.

When can we trust what we believe—that "teams and players have winning streaks," that "flattery works," or that "the more people who agree, the more likely they are to be right"—and when are such beliefs suspect? Thomas Gilovich offers a guide to the fallacy of the obvious in ev
Paperback, 216 pages
Published March 5th 1993 by Free Press (first published 1991)
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Aug 17, 2009 rated it it was amazing
I thought this was a remarkable book – five stars all the way – up until the last couple of chapters when it really didn’t live up to its initial promise. But I’m giving it 5 stars anyway, because the first two parts are so good they are more than worth whatever effort is necessary to get your hands on this.

It is a bit old now – first printed in 1991, but many of the ideas are still essential if you have any interest in how our judgement and decision making processes can land us in trouble.

The f
Shannon Hedges
Dec 31, 2008 rated it really liked it
This book examines cognitive biases. Gilovich describes various dubious beliefs, such as faith healing and other homeopathic nonsense. He investigates the thought processes that affect our ability to make sound judgments. It encouraged me to examine the shortcomings of my own reasoning. Highly recommend.
Sep 11, 2020 rated it liked it
I was assigned How We Know What Isn't So as part of a critical thinking course my freshman year of university, and it's one of the few books outside of my major that I've kept all these years.

On reread I realize that I was conflating my love of the class with the content of the book. There's nothing wrong with it - it's an academic, clear-eyed look at all the ways our mind can steer us wrong. We may think we're making a decision on complete data when there's actually a chunk that's missing. We
Ruxandra Tihon
Oct 13, 2019 rated it it was amazing
Wonderful book, recommend it to anyone looking to improve their critical thinking. Written in the 90’s but very much relevant for today’s world.

“ To truly appreciate the complexities of the world and the intricacies of human experience, it is essential to understand how we can be misled by the apparent evidence of everyday existence. This, in turn, requires that we think clearly about our experiences, question our assumptions, and challenge what we think we know. “
Eric B. Kennedy
Dec 28, 2020 rated it really liked it
In "How We Know What Isn't So," Thomas Gilovich lays out a useful and engaging introduction to the importance of critical thinking, the risks of cognitive bias, and the implications of decision-making when we aren't attentive to these concerns. Compared to many books & articles on the cognitive science of fallacious reasoning, Gilovich's book is relatively engaging and easy to read. (I do have some minor qualms about the typesetting of the 1993 paperback edition, which is a fairly dense wall of ...more
Samantha Rizzo
Apr 18, 2019 rated it liked it
This book is reminiscent of other works I’ve read such as Shermer’s Why People Believe Weird Things and Mackay’s Extraordinary Popular Delusions and the Madness of Crowds, neither of which I found particularly interesting (the latter I didn’t even bother to finish).

As I’ve already read quite a bit of literature on this topic the book comes across to me as common sense. Humans generalize, and tend to discount the information that serves their preconceived notions, and will instead scrutinize any
May 22, 2017 rated it liked it
Although this was an interesting book, as someone with a psychology degree there wasn't anything ground breaking in it. It gave a thorough discussion of why people are so prone to falling for erroneous beliefs and it showed how difficult it was to do otherwise using evidence of psychological studies coupled with some quite detailed explanations. I think I wanted more examples over and above the theory, but they were confined to the last couple of chapters dealing with belief in alternative medic ...more
Drew Flynn
Feb 03, 2018 rated it really liked it
Some chapters were more interesting than others, but those interesting ones were at times incredible. The book makes you want to constantly keep reading more, while your brain wants you to chill so it can process it all. A wonderful dilemma.
Sharif Mahmud
Mar 31, 2017 rated it it was amazing
Eye-opener, mind-bending tour to the everyday experience.
Jan 27, 2020 rated it liked it  ·  review of another edition
Recommended to Jeff by: Stephen Dubner
In the Freakonomics podcast #382 (, Stephen Dubner called this one of his favorite books ever, so I decided to add it to my reading list. I found it to be an interesting read that really challenged me to consider how and why I think about some things that seem crystal clear to me. At a minimum, I will benefit from the fore-knowledge that I just *might* not have all the facts and information about some topics if I want to make informed decisions, and perha ...more
Jan 20, 2012 rated it really liked it
This is a really excellent book, though there are a lot more engaging reads in the psychology-for-general-public read as of late. If there weren't so many better written ones as of late and the book itself weren't nearly twenty years old old (I am hoping for a second edition), I'd have given it five stars (there's more research on how people think and decide more recently). Unfortunately, lately, I've been meeting lots of people endorsing truly ridiculous ideas without thinking critically about ...more
Jun 11, 2013 rated it liked it
This is a good solid work about people's irrational beliefs, covering just about all the basic psychological mechanisms. It's not breaking new ground, but that's because it's more than 20 years old. Still, it brings a few things to the table that I haven't seen in most other discussions of this topic:

- The authors recognize that while we see many occasions when people form opinions that are incorrect or at best not supported by (complete & unbiased) evidence, human nature leads us to make good d
How We Know What Isn't So is a researched book on social psychology by Thomas Gilovich, a psychology professor at Cornell. It talks about why our mind seeks dubious or erronous information to aid our biases, rather than negating or clarifying them, and supplements its claims by examples of researches that did so in the past.

Reading this book would help you to look at the usually pervading superstitions and medical 'quacks' or evidence in support of existence of paranormal activities, or any oth
Apr 03, 2008 rated it it was amazing
Shelves: non-fiction
Author Thomas Gilovich gives us concrete examples of the ways in which people can come to believe things for which there is no genuine scientific evidence, and the common errors people make when trying to make sense of statistical and probabilistic data. He shows us how people can consciously or unconsciously delude themselves, and how we so often ignore evidence we don’t like and concentrate on evidence that appears to support views that we want to believe are true. The book is moderately schol ...more
Nov 05, 2011 rated it it was amazing
This book makes you think about how unthinking we are, from believing that infertile couples are more likely to have a biological child once they have adopted one.(not too many consequences here) to belief that seal penises are the natural Viagra, (40,000 seal penises found in one raid). We tend to notice only those events which reinforce our own beliefs and prejudices - we ignore evidence which disproves them. Every statement is peppered with entertaining real-life examples including an explana ...more
Jake Losh
May 21, 2012 rated it it was amazing
This is an exceptional book. I got about six chapters deep into it several months ago when I decided that I was trying to read it way too fast. At under 200 pages (excluding notes and references) this is an extremely dense and comprehensive treatment of so many aspects of human reasoning. This book is intense and will make you question so many things about the way you see the world. Once you start to read it, you'll start to see the application of its lessons everywhere and you cannot unsee them ...more
Feb 01, 2008 rated it it was amazing
Recommends it for: amateur psychologists, skeptics, critical thinkers
How We Know What Isn't So is an outstanding read for anybody who tends to be a skeptic or merely wants to be a critical thinker. While the author is an academic, the book is well-written and actually a fairly quick and easy read. The purpose is to explore how we come to understand things, and primarily it focuses on how we come to believe things that are not true. Whether it is ESP or alien abductions or more common myths like strange things happening during full moons, Gilovich documents a wide ...more
Sarah Whitney
Apr 03, 2010 rated it it was amazing
Shelves: non-fiction, a-gift, own, 2010
Gilovich is an impressive academic and skilled writer. I really enjoyed this book, especially part II. I'd recommend this for anyone who is interested in the validity of their beliefs and the science behind how people form cognitive biases. Reads a bit like something you'd be assigned in college and it is quite scholarly, but in a very nice way, with citations galore. I previously read "Don't Believe Everything You Think: The 6 Basic Mistakes We Make in Thinking" by Thomas E. Kida and was disapp ...more
Mar 05, 2011 rated it really liked it
It's a good complementary reading with another book "Mistakes were made but not by me" by Carol Tavris and Elliot Aronson, where both books attest human fallibility to consider their biases in offering reasons to different situation with seemingly unexplained phenomena and so taking early and foolish arguments and transform them in believes without looking upon scientific and statistical justification of everyday experiences and logic fallacies. ...more
Aug 14, 2013 rated it really liked it
I found this a very informative discussion of the many ways our brains can persistently mislead us into erroneous conclusions via otherwise perfectly normal, useful and effective psychological processes.
Sep 28, 2016 rated it really liked it  ·  review of another edition
This is a must read for those interested about cognitive bias. It will serve as a fantastic companion to "Thinking Fast and Slow," although if I could only read one of the two I'd go with "Thinking Fast" since it much better structured and easier to understand. ...more
Joshua Born
Jan 31, 2020 rated it it was amazing  ·  review of another edition
Shelves: audiobook, nonfiction
Thomas Gilovich's How We Know What Isn't So is something of a modern classic in the topic of how mistakes in interpreting evidence lead to false beliefs. The book was written in the early nineteen nineties by a social psychologist, and chapters are devoted to such perennial fallacies as the various forms of confirmation bias and to the perils of second- and third-hand information, among others. A chapter on the psychological tendency to falsely believe that one's own beliefs and values are more ...more
Mostly a book about cognitive and social psychology, by a research psychologist, but with some examples in the form of things "everybody knows" but which "just ain't so" - ESP, New Age "holistic" treatments, and (less supernaturally) common but rarely-successful social behavior. Kudos to the author for sticking pretty much to what he knows (note how the three examples are focused on the mind or social interaction), but it's a relatively light treatment of each.

The preparatory chapters on how peo
Robert Bogue
It’s what we know that ain’t so that gets us in trouble. Whether you prefer that Artemus Ward quote from To Kill a Mockingbird or you attribute the saying to Mark Twain, the sentiment is the same. Knowing something rarely gets us in trouble. Thinking that we know something we don’t can have bad to tragic consequences. Understanding how our thinking goes wrong is at the heart of How We Know What Isn’t So: Fallibility of Human Reason in Everyday Life. Thomas Gilovich’s work has come up in several ...more
Jacob Lehman
Jan 27, 2019 rated it it was amazing
Shelves: business, thinking
Gilovich does an excellent job of distinguishing between sources of error: e.g., focus on confirmatory evidence, tricky balance between trusting one's own experience and larger samples, and articulation of consequences. I fear some of the most subtle points (e.g., about the value of agency/placebos in a medical context) might get lost in the preaching to the choir aspects of scientific inference, and he doesn't really address how to identify truth when experimentation is impossible... but his ow ...more
May 29, 2017 rated it it was amazing
One of my favorites in the field.

There is a lot of more recent work in behavioral decision-making but this is still one of my favorites. I think it is a great introduction to the field. Even though it is dated, I think the basic ideas hold up and are explained and supported in clear ways. A lot of the more recent books are written to sell well more than to explain.

("Thinking Fast and Slow" by Daniel Kahneman is an exception that I highly recommend).
Ed Terrell
Jan 09, 2019 rated it really liked it
Shelves: 2019
People hold such beliefs because they seem to be the "irresistible products of their own experience." Robert Merton

Beliefs are like possessions- Robert Abelson

This is a good summary of how our best objective view of the world can be at such odds with that of another person. The table of contents says it all. First, we identify a random pattern as something real (Something out of Nothing), we then seek out only the confirming evidence (Too Much from Too Little). We make a biased evaluation from a
Sep 04, 2019 rated it really liked it
Wanna' know why people believe stupid stuff? This book may help.

It's a pop academic book by a psychology professor from Cornell. It covers a lot of stuff about biases in human thinking.

It's a good read, but not a great one. I felt it needed to be harder hitting sometimes. Also, there seemed to be no overarching summary. It was all chapters about people do this, and then people do this, but nothing tying it all together well.
Mar 11, 2021 rated it really liked it
This book takes a really close and detailed look at the way humans reason given the facts presented to us. The author starts off by examining the phenomenon of "hot hand" in basketball and the lack of hard evidence for its validity. And yet, regardless, of the collected evidence, we continue to believe in it, including basketball professionals. The author proceeds with more examples and unpacks possible reasons for why our minds works the way it does. Excellent food for thought! ...more
Manoj Saha
May 07, 2017 rated it really liked it
Read this book as it was suggested as a textbook while doing an online course on "Thinking" where the reference book is "Thinking, fast and slow" - most important thing it establishes is that exact sciences does not force us to think before we accept and how we shape our beliefs are quite important as they go on to shape us. Encouraging for spending time on understanding psychology. ...more
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From Wikipedia:

Thomas D. Gilovich (born 1954) is a professor of psychology at Cornell University who has researched decision making and behavioral economics and has written popular books on said subjects. He has collaborated with Daniel Kahneman, Lee Ross and Amos Tversky.

Gilovich earned his B.A. from the University of California, Santa Barbara and his Ph.D. in psychology from Stanford University

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