Inevitable Illusions

Inevitable Illusions : How Mistakes of Reason Rule Our Minds by Massimo Piattelli-Palmarini

ISBN 047115962X Well translated from the Italian, this fascinating book considers a range of "cognitive illusions", fallacies you can no more avoid without careful thought than you can perceive an optical illusion correctly without measuring it.


I'll put some up once I recover my copy of the book from the friend to whom I lent it. They have to be stated quite carefully. Here's one trivial example that I can remember:

Most Italians think that the Italian Peninsular runs north-south. In fact, it runs NW-SE. Most Italians cannot correctly remember the relative positions, east-west, of major Italian cities.

''I operate under a very similar illusion. The main street where I live runs NW-SE but I generally think of it as north-south. Go to mapquest, pull up Pikesville, MD, and look at route 140 to see what I mean.

A straw poll amongst my friends indicates that a similar result holds for the island of Great Britain. For those of you familiar with the British Isles, ask yourself: is Glasgow east or west of Bristol? Now look it up on a map.

The others in the book are a lot more sophisticated, and worrying, than that. One result given in the book, that is now burned into my brain, is that the more people tend to be confident of an (intuitive/guessed) answer the less accurate it is likely to be.

{The phenom seems like a UsefulLie. Suppose you were talking a lot about a given diagonal line. As long as the topic remains being only or mostly about that line, a linear coordinate system keeps the conversation simpler than using a 2D one. In fact, one could talk about it as a percentage, zero at top and 100% at the bottom. "Point X is 60% of the way down."}

A lot of Piattelli-Palmarini's illusions rely on deeply ingrained erroneous modes of thinking. One of his results relates to the MontyHallProblem. From personal experience I can confrim P-P's result that knowing the correct answer, and how to derive it really doesn't help very much. I still have to think very, very, carefully to get the MHP right. A similar but differently worded problem will still throw me. -- KeithBraithwaite

Now that PeteMcBreen has also mentioned this book (on WhoShotJfk), I now have an incentive to put some examples up here. Soon, soon. -- KeithBraithwaite

The book TheLogicOfFailure is somewhat related. -- FalkBruegmann

I confess that I was highly unimpressed by InevitableIllusions. The authors seemed to spend more time scoffing at the reader for being irrational than conveying interesting information. :-) In some cases, their analyses of alleged irrationalities were just plain wrong; see for a discussion. (The "book on irrationality" mentioned about 1/3 of the way down is InevitableIllusions.) -- GarethMcCaughan

I would have to agree. The concept that there are puzzles that naturally defeat our mental reasoning is very interesting, but the book has too few real examples, and drags on too long about the same points over and over. The best two examples are the MontyHallProblem and the BirthdayProblem. I can't recall if it discussed the PrisonersDilemma or just mentioned it, but that would be a good example as well.

Inevitable Illusions, while interesting, falls down on

A far better source, on much the same material:

How we know what isn't so : the fallibility of human reason in everyday life, Thomas Gilovich, New York, N.Y., Free Press, 1991, ISBN 0029117054 , LCCN 90026727.

How We Know strikes me as more complete and detailed, more helpful and hopeful for would-be rational thinkers, and incomparably more readable. Of course, the style and tone of P-M's book may reflect poor translation rather than poor writing, but Gilovich's book remains far more enjoyable, to my taste anyway.

I just read this book and my feelings about it are very mixed. Most of it is a popular re-presentation of stuff already present in JudgmentUnderUncertainty by DanielKahneman? and AmosTversky?. JUU is a collection of research papers and thus somewhat tough going for laypeople (such as I am) in empirical cognitive research. Thus an accessible book is valuable in itself. Were it not for the often arrogant tone, and, what's more annoying, P-P spends far two much space trying to put down his academic adversaries. His general readers are in no position to judge these arguments - and have to take his biased word for it. -- MichaelSchuerig

I was also disappointed; see for my review.

I found your quote in the survey about Linda to be interesting, but at least as you present it I don't think it's surprising at all. It may be a Western thing, or an American thing, or a human thing, but when presented with a list like that there's an implication that they're discrete sets:

This has less to do with illogical thinking than with language, I think. I wonder how the results would differ if instead it were:

Recently, a book has been published that suggests that East and West people reason differently. Westerners tend to view attributes as self-standing and isolated, while Eastern thinking is characterized by more observations about relationships between things. This is possibly the result of the complex family social structures in many Asian cultures.

Mmm... self standing attributes vs relationship between things... that sounds like the BundleSubstanceMismatch problem, does this mean that Western thinking is object oriented and Eastern thinking is relational?

The Geography of Thought: How Asians and Westerners Think Differently...and Why by Richard Nisbett. ISBN 0743216466

Yes, but how will the OneChildPolicy? and resulting lack of first cousins, aunts, or uncles and other social constructs change Eastern thinking in Asia? (See, e.g.,,pubID.26835/pub_detail.asp)

Compare with JudgmentUnderUncertainty which is a sound collection of articles on this topic.

See Also: EverythingIsRelative


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