Thinking fast and slow: book Summary

What do you get in this post: in this post, I have covered all chapter’s lessons.

Are you excited like me?

So, stay tuned till the end.

For just 1 page summary you can click here.

Why do you have to read Thinking Fast and Slow book summary?


This book analyses your thoughts in 2 modes

system 1 fast and emotional

system 2 is slower and more logical.


The way this book has explained our thinking system and decision-making process is how you think about the world so be in the flow with me and you are going to feel how knowledgeable this book is.

It will be going to change the way you think.

Want to know how?

Favorite quote:

“Nothing in life is as important as you think it is, while you are thinking about it”

Let’s get started.

This book is divided into 5 parts and every part includes chapters. Don’t worry I will going to cover all the important points.

Part 1 Two systems.

The Characters of the Story

In this chapter, the author explains about two systems of brains proposed by the psychologists Keith Stanovich and Richard West.

System 1 operates automatically and quickly, with little or no effort and no sense of voluntary control. System 2 allocates attention to the effortful mental activities that demand it, including complex computations. The operations of System 2 are often associated with the subjective experience of agency, choice, and concentration.

here are some examples of the automatic activities that are attributed to System 1:

Detect that one object is more distant than another.

Orient to the source of a sudden sound.

Complete the phrase “bread and…” Make a “disgust face” when shown a horrible picture.

Detect hostility in a voice.

Answer to 2 + 2 =?

Read words on large billboards.

Drive a car on an empty road.

Find a strong move in chess (if you are a chess master).

Understand simple sentences.

Recognize that a “meek and tidy soul with a passion for detail” resembles an occupational stereotype.

(They occur automatically and require little or no effort.)

The highly diverse operations of System 2 have one feature in common: they require attention and are disrupted when attention is drawn away. Here are some examples:

Brace for the starter gun in a race.

Focus attention on the clowns in the circus.

Focus on the voice of a particular person in a crowded and noisy room.

Look for a woman with white hair.

Search memory to identify a surprising sound.

Maintain a faster walking speed than is natural for you.

Monitor the appropriateness of your behavior in a social situation.

Count the occurrences of the letter in a page of text.

Tell someone your phone number.

Park in a narrow space (for most people except garage attendants).

Compare two washing machines for overall value.

Fill out a tax form.

Check the validity of a complex logical argument.

(In all these situations you must pay attention, and you will perform less well, or not at all, if you are not ready or if your attention is directed inappropriately. System 2 has some ability to change the way System 1 works, by programming the normally automatic functions of attention and memory.)

The Lazy Controller

A team of researchers at the University of Oregon explored the link between cognitive control and intelligence in several ways, including an attempt to raise intelligence by improving the control of attention.

During five 40-minute sessions, they exposed children aged four to six to various computer games specially designed to demand attention and control.

In one of the exercises, the children used a joystick to track a cartoon cat and move it to a grassy area while avoiding a muddy area.

The grassy areas gradually shrank and the muddy area expanded, requiring progressively more precise control.

The testers found that training attention not only improved executive control; scores on nonverbal tests of intelligence also improved and the improvement was maintained for several months.

Other research by the same group identified specific genes that are involved in the control of attention,

showed that parenting techniques also affected this ability, and demonstrated a close connection between the children’s ability to control their attention and their ability to control their emotions.

Part 2: Heuristics and Biases

Anchoring and the Two Systems

The effects of random anchors have much to tell us about the relationship between System 1 and System 2.

Anchoring effects have always been studied in tasks of judgment and choice that are ultimately completed by System 2.

However, System 2 works on data that is retrieved from memory, in an automatic and involuntary operation of System 1.

System 2 is therefore susceptible to the biasing influence of anchors that make some information easier to retrieve.

Furthermore, System 2 has no control over the effect and no knowledge of it.

The Science of Availability

A salient event that attracts your attention will be easily retrieved from memory. Divorces among Hollywood celebrities and s*x scandals among politicians attract much attention, and instances will come easily to mind. You are therefore likely to exaggerate the frequency of both Hollywood divorces and political sex scandals.

A dramatic event temporarily increases the availability of its category. A plane crash that attracts media coverage will temporarily alter your feelings about the safety of flying.

Accidents are on your mind, for a while, after you see a car burning at the side of the road, and the world is for a while a more dangerous place.

Personal experiences, pictures, and vivid examples are more available than incidents that happened to others, mere words, or statistics.

A judicial error that affects you will undermine your faith in the justice system more than a similar incident you read about in a newspaper.

Resisting this large collection of potential availability biases is possible, but tiresome.

You must make the effort to reconsider your impressions and intuitions by asking such questions as, “Is our belief that theft by teenagers is a major problem due to a few recent instances in our neighborhood?” or “Could it be that I feel no need to get a flu shot because none of my acquaintances got the flu last year?”

Maintaining one’s vigilance against biases is a chore—but the chance to avoid a costly mistake is sometimes worth the effort.

How to Discipline Intuition

Your probability that it will rain tomorrow is your subjective degree of belief, but you should not let yourself believe whatever comes to your mind. To be useful, your beliefs should be constrained by the logic of probability.

So, if you believe that there is a 40% chance that it will rain sometime tomorrow, you must also believe that there is a 60% chance it will not rain tomorrow, and you must not believe that there is a 50% chance that it will rain tomorrow morning.

And if you believe that there is a 30% chance that candidate X will be elected president and an 80% chance that he will be re-elected if he wins the first time, then you must believe that the chances that he will be elected twice in a row are 24%.

Part 3: Overconfidence

The Illusion of Understanding

The word is, of course, knew. Some people thought well in advance that there would be a crisis, but they did not know it.

They now say they knew it because the crisis did in fact happen. This is a misuse of an important concept.

In everyday language, we apply the word know only when what was known is true and can be shown to be true. We can know something only if it is both true and knowable

The core of the illusion is that we believe we understand the past, which implies that the future also should be knowable, but in fact, we understand the past less than we believe we do. Know is not the only word that fosters this illusion.

To think clearly about the future, we need to clean up the language that we use in labeling the beliefs we had in the past.

The Social Costs of Hindsight

The mind that makes up narratives about the past is a sense-making organ.

When an unpredicted event occurs, we immediately adjust our view of the world to accommodate the surprise.

Imagine yourself before a football game between two teams that have the same record of wins and losses.

Now the game is over, and one team trashed the other. In your revised model of the world, the winning team is much stronger than the loser, and your view of the past as well as of the future has been altered by that new perception.

Learning from surprises is a reasonable thing to do, but it can have some dangerous consequences.

A general limitation of the human 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 of any part of it), you immediately lose much of your ability to recall what you used to believe before your mind changed.

Recipes for Success

The sense-making machinery of System 1 makes us see the world as more tidy, simple, predictable, and coherent than it really is.

The illusion that one has understood the past feeds the further illusion that one can predict and control the future.

These illusions are comforting. They reduce the anxiety that we would experience if we allowed ourselves to fully acknowledge the uncertainties of existence.

We all have a need for the reassuring message that actions have appropriate consequences, and that success will reward wisdom and courage.

The Illusion of Validity

System 1 is designed to jump to conclusions from little evidence—and it is not designed to know the size of its jumps.

Because of WYSIATI (What you see is all there is), only the evidence at hand counts. Because of confidence by coherence, the subjective confidence we have in our opinions reflects the coherence of the story that System 1 and System 2 have constructed.

The amount of evidence and its quality do not count for much, because poor evidence can make a very good story.

For some of our most important beliefs, we have no evidence at all, except that people we love and trust hold these beliefs.

Considering how little we know, the confidence we have in our beliefs is preposterous—and it is also essential.

Part 4: Choices

Prospect Theory

We always like to avoid to risk.

Consider these two problems:

Problem 1: Which do you choose?

Get $900 for sure OR a 90% chance to get $1,000

Problem 2: Which do you choose?

Lose $900 for sure OR 90% chance to lose $1,000

Like the vast majority of individuals, you were likely to risk concern in problem 1. The subjective worth of a $900 gain is unquestionably greater than 90% of the subjective value of a $1,000 gain.

Now examine your preference in problem 2. If you are like most other people, you chose the gamble in this question.

The explanation for this risk-seeking choice is the mirror image of the explanation of risk aversion in problem 1: the (negative) value of losing $900 is much more than 90% of the (negative) value of losing $1,000.

The sure loss is very aversive, and this drives you to take the risk.

Bad Events

The concept of loss aversion is certainly the most significant contribution of psychology to behavioral economics.

This is odd, because the idea that people evaluate many outcomes as gains and losses, and that losses loom larger than gains, surprises no one.

Loss aversion

Many of the choices we have in life are confusing. We must choose whether to accept the gamble or reject it because there is a chance for gain and a chance for loss.

Loss aversion is the tendency to prioritize avoiding losses over achieving gains.

Using money as an example, we are probably more driven to avoid losing money than to gain it.

This is the reason why a lot of people don’t establish ambitious goals.

You lose money when you establish a goal that you never accomplish.

You make money when you fulfill your target.

He argues that after achieving a certain goal, many people feel like their efforts were wasted because they don’t see the sense in going above and beyond; instead, they are more concerned with preventing losses than with gaining anything.


Even when the losing side knows they have no chance of winning, they frequently continue fighting, holding to whatever hope there is that they may escape losing.

This is because defeat is never simple to accept.

The obvious result we all picture when laying out a new plan is a success.

Although there is typically only one strategy for success, there are many different ways that things can go wrong, therefore failure is more likely.


Regret is a punishment as well as an emotion.

We frequently treat ourselves regrettably, and something goes wrong.

and for this reason, many of our decisions are driven by a fear of regret.

We avoid making choices that can generate regret and frequently pass up opportunities as a result.

Part 5: Two selves

Biology vs. Rationality

Decisions that do not produce the best possible experience and erroneous forecasts of future feelings—both are bad news for believers in the rationality of choice.

The cold hand study showed that we cannot fully trust our preferences to reflect our interests, even if they are based on personal experience, and even if the memory of that experience was laid down within the last quarter of an hour! Tastes and decisions are shaped by memories, and the memories can be wrong.

The evidence presents a profound challenge to the idea that humans have consistent preferences and know how to maximize them, a cornerstone of the rational-agent model.

Inconsistency is built into the design of our minds.

We have strong preferences about the duration of our experiences of pain and pleasure. We want the pain to be brief and the pleasure to last.

But our memory, a function of System 1, has evolved to represent the most intense moment of an episode of pain or pleasure (the peak) and the feelings when the episode was at its end.

A memory that neglects duration will not serve our preference for long pleasure and short pains.

“You are thinking of your failed marriage entirely from the perspective of the remembering self. A divorce is like a symphony with a screeching sound at the end— the fact that it ended badly does not mean it was all bad.”

“This is a bad case of duration neglect. You are giving the good and the bad part of your experience equal weight, although the good part lasted ten times as long as the other.”

Experienced Well-Being

The experience of a moment or an episode is not easily represented by a single happiness value. There are many variants of positive feelings, including love, joy, engagement, hope, amusement, and many others.

Negative emotions also come in many varieties, including anger, shame, depression, and loneliness. Although positive and negative emotions exist at the same time, it is possible to classify most moments of life as ultimately positive or negative.

We could identify unpleasant episodes by comparing the ratings of positive and negative adjectives. We called an episode unpleasant if a negative feeling was assigned a higher rating than all the positive feelings.

Thinking About Life

In the DRM studies, there was no overall difference in experienced well-being between women who lived with a mate and women who did not.

The details of how the two groups used their time explained the finding. Women who have a mate spend less time alone, but also much less time with friends.

They spend more time making love, which is wonderful, but also more time doing housework, preparing food, and caring for children, all relatively unpopular activities.

And of course, a large amount of time married women spend with their husbands is much more pleasant for some than for others.

Experienced well-being is on average unaffected by marriage, not because marriage makes no difference to happiness but because it changes some aspects of life for the better and others for the worse.

One reason for the low correlations between individuals’ circumstances and their satisfaction with life is that both experienced happiness and life satisfaction are largely determined by the genetics of temperament.

A disposition for well-being is as heritable as height or intelligence, as demonstrated by studies of twins separated at birth.

People who appear equally fortunate vary greatly in how happy they are. In some instances, as in the case of marriage, the correlations with well-being are low because of balancing effects.

The same situation may be good for some people and bad for others, and new circumstances have both benefits and costs.

In other cases, such as high income, the effects on life satisfaction are generally positive, but the picture is complicated by the fact that some people care much more about money than others do.

Thank you for your time.

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