Thinking, Fast and Slow by Daniel Kahneman


It is very difficult to judge, review or analyze a book that basically challenges the very idea of human “Rationalism”. Are humans perfectly rational? This dude, Daniel Kahneman, won a Nobel Prize in Economics for saying they are not. An ordinary person might have been treated with glare or a stinging slap if he said that to someone’s face. We simply don’t like being told that we are not very rational and certainly not as intelligent as we think we are. Hidden in the depths of our consciousness, are some ‘actors’ that keep tempering with our ‘rationality’. And we almost consciously allow this to happen.

All in all, this book is a tour de force of Behavioral Psychology. Explaining how our mind comes to conclusions and makes decisions, Kahneman explains that our intuition and decision making part of brain has two personalities. These personalities, he says, are not two different or distinct systems but to understand them better, we will have to assign personalities not only to understand them better but also to be able to relate to them on a personal level.

The two systems are called system 1 and system 2, for the sake of convenience. System 1 is vigilant, impulsive, judgmental, easily manipulated, highly emotional.


System 2, on the other hand is the total opposite of system 1, it is very intelligent, indolent, mostly drowsing off in the back of our head, difficult to convince and extremely stubborn, and it only comes to action when there is some sort of ‘emergency’. Both these systems are susceptible to a number of biases, system 1 more than system 2.

I thought Kahneman would build up this narrative systematically but he goes on to give us a tour of his years of research, experiments and surveys exploring every nook of our conscious human mind. He focuses on a diverse set of heuristics and biases that influence our judgments in everyday life. With some brilliant experiments and survey reports, he convincingly elaborates the effects that these biases have on our decisions. Never forgetting to highlight the fallacies of our consciousness, he touches on a number of other important breakthroughs in the world of psychology.



This is a very simple case of visual illusion where we see two lines of same size appearing to be of varying lengths. Even after knowing that they are equal and the illusion is created by the fins attached to them, our system 1 still impulsively signals that one of them is longer then the other.

Through this simple illustration, he moves on to introduce Cognitive Illusions, which are more fascinating, and are drastically more effective.

Kahneman contends that it is extremely difficult to overcome heuristic biases. Although, through methods like using statistical formulas and deliberate scrutiny we can ‘rationalize’ our decisions to some extent. Still, we are inherently prone to fall for dazzling rhetoric and dashing figures, we believe in myths and incidents that are as improbable as they are ludicrous, because this is the way we see things. But this is not undesirable altogether, some of the intuitive abilities are an evolutionary blessing that help us understand emotions and make correct decision in split seconds. Neither does the author deems it expedient to overcome these biases, but only to recognize them and put our system 2 to work before making crucial judgments.




I have attempted to summarize some heuristics and Biases that I thought would make a fascinating introduction to tempt a novice like me to further explore the subject.

They are just the tip of iceberg and not by any means exhaustive and just comprise a small part of what this book is all about.


Associative machine: System 1 works in surprising ways, read this


Now, a lot happened in last few seconds when you read these two words. You wore an expression of disgust and a very bad image came to your mind, your body too reacted in disgust and for short time you might not want to eat bananas. All of this was automatic and beyond your control. It was “The Associative Machine” of system 1. We associate seemingly unrelated images and with some imagination, form an image. Our brain loves patterns and some times it sees things that aren’t even there.

A very interesting clip in which Simon Singh shows associative machine at work :…


Priming: Exposure to a word causes immediate changes in the ease with which many related words can be evoked. If you have recently heard the word EAT, you are temporarily more likely to complete the word fragment SO_P as SOUP than as SOAP. The opposite would happen if you had just seen WASH.

Similarly, exposure to an idea or event can also have similar temporary effect on our behavior. (“Florida Effect”)


Cognitive Ease: We all love it when we don’t have to work too hard because system 2 doesn’t like being bothered. So we admire and rather look for cognitive ease. Things that are less complex have a positive effect on our behavior. Psychologists use the term “Mind at ease puts a smile on the face”. Similarly, smiling and laughing can also ease our mind (system 1) and make us feel confident and in control. Anything that is easy to understand (read or see) is likely to have a more positive effect on us as compared to anything that we have a hard time understanding or visualizing.


Exposure Effect: We are more likely to choose the thing we are more familiar with. The principle that “Familiarity breeds liking” suggests that we are more inclined towards anything that is familiar and has been exposed to us before in past. The more the exposure is, the more we will be inclined towards it.

This principle is excellently illustrated in Will Smith’s “Focus” (2015).

a similar trick is used to con a billionaire.


Normality illusion: Things that recur with greater frequency are considered normal, no matter how horrendous they are. Two people killed in a terrorist attack in a western country are more likely to be mourned then a hundreds of children killed in Gaza by a missile strike. Simply due to the fact that children in Gaze get bombed all the time, while a terrorist attack that kills innocents is sort of rarity in Europe and America. (The same concept is present in Orwell’s Animal Farm in which pigs start to dominate other animals and it becomes the norm after a while.)


Substitution: If a satisfactory answer to a hard question is not found quickly, System 1 will find a related question that is easier and will answer it. For instance when asked How happy are you with your life these days? Its more likely that we don’t use a broad frame to answer the question and substitute it with a simpler question “What is my mood right now?”. System 1 can readily answer the substitute question but to answer the real question, System 2 would have to be excited, which as we know System 2 doesn’t like. In everyday life, we use this to avoid making decisions and expressions based on factual background and therefore make an impulsive and sometimes irrational comment to a difficult question.


What you see is all there is: We take pride in our intuitive abilities which leads us to believe that we know the whole truth, no matter how fallible our sources are, and not withstanding the fact that there is always another side of the picture. When we hear a story or an incident, we tend to accept it as a fact without considering any view dissenting or contradicting it. Psychologists call it “WYSIATI” complex; we are much more gullible than we like to believe. But it is again the mischief of System 1 that leads us to believe a narrative impulsively and without further inquisition as to its authenticity. It is also another example of our intuitive tendency to see things in a narrow frame.


Loss Aversion: Call it a gift of evolution or survival instinct, but we are naturally loss averse in most of our decisions. We are more likely to abandon a huge profit if there is some probability of an equally huge loss. We do want to have more, but not at the cost of putting our own at stake, we relish our possessions more than our desire to have more.


Overconfidence and Hindsight bias: A general limitation of our mind is its imperfect ability to reconstruct past states of knowledge, or beliefs that have changed. Once you adopt a new view of the world (or any part of it), you immediately lose much of your ability to recall what you used to believe before your mind changed. We see people everyday saying that what just happened was what they always thought would happen and they, in their overconfidence, start believing that they always knew in hindsight that such an event was probable. (see Halo Effect)


Prospect theory: This theory attempts to explain the way people choose between probabilistic alternatives that involve risk, where the probabilities of outcomes are known. Kahneman illustrates it through this graph


This theory is one of his most important in the field of behavioral economics. Owing to its complexity, I can not summarize it here.


I highly recommend this book to anyone with a serious interest in Behavioral Psychology. Don’t waste your time on self-help books when you can read the real science behind all those quirky best-sellers.


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