Thinking Fast and Slow Summary

“Libro. Thinking, Fast and Slow” by fernand0 is licensed under CC BY-SA 2.0

Your brain has two systems:

System 1 (fast, intuitive)

The first system describes how the brain forms thoughts. The first system is fast, frequent, and automatic. It is responsible for observing whether a particular item is far from the other, localizing where precisely a specific sound is coming from, displaying disgust when seeing a disgusting image, and understanding simple sentences. Etc.

The first system is lazy and prevents you from using your intelligence, and that’s the reason why you end up doing wrong and poor decisions.

System 2 (slow, analytical)

The second system is slow, needs effort, calculating, and is very much conscious. The system is responsible for when you prepare yourself for the start of a sprint, direct your attention to someone at a wedding party, try to recognize a specific sound, determine if something is appropriate, park your vehicle in a very small space, count the number of B’s in a certain text, etc.

The second system allows you to think before making any important decisions. It is very conscious and aware of everything around you. It is responsible for you having self-control.

However, these two systems do not work together at the same time. One system is always trying to take over the other. For example, when lazy system 1 faces difficult situations it can’t solve, system 2 jumps in and take control. Sometimes system 1 thinks it can handle challenging problems and that’s when you think a certain problem is simple, which results in making bad decisions.

The reason why these two systems operate in this way is to save energy. System 1 uses the minimum amount of energy, while system two needs your focus and attention and uses a lot of energy. Therefore, when system one can handle certain situations, system 2 will not activate, in this case, you don’t use your intelligence, and your brain remains lazy.

Cognitive Ease: Your Brain wants to take the path of least resistance.

Here Kahneman talks about how the brain wants to take the path of least resistance. Most people allow system 1 of the brain to take complete control because it does not require critical thinking and decision-making. System 1 does not need a person to use their intelligence, and hence it is least resistant, unlike system 2 which requires thinking and observing the situation first.

Question substitution: when face with a difficult question, we answer a cognitively easier one

According to Daniel Kahneman, system 1 of our brain always substitute a simpler question for a difficult one. In the book, Daniel gives an example which he called the “Linda problem.” Linda is an imaginary person, she’s young, single, outspoken, and intelligent, and she is also very concerned with discrimination and social justice. In the book, Daniel asks whether it was more probable that Linda is a bank teller or that she is a bank teller and an active feminist. More people would say a “feminist bank teller” is correct than a “bank teller,” which violates the laws of probability. In an actual sense, every feminist is a bank teller, but in this case, system 1 substitutes the more straightforward question, “is Linda a feminist?”, neglecting the occupation qualifier. People are fond of substituting hard questions with easier ones, this is because they are reluctant to use their brains, and system 1 is activated instead of system 2 that works more appropriately.

WYSIATI (what you see is all there is)

In this theory, Daniel states that when the brain makes a choice, it goes for what it knows and has observed already rather than considering the known and unknowns. He further explains that people fail to take into consideration complexity and that their understanding of the world consists of a small and necessarily un-representative set of observations. He also states that the brain does not account for the role of chance and therefore always assumes what the future events will be similar to the past events.

Framing and choice architecture: Your Opinion can change depending on how you’re asked

Framing is how decisions are presented. According to Kahneman, most people spend their lives in a default mode; they make decisions based on intuition. The mind working with fast thinking and instant response is adequate. However, thinking fast is not always enough, the slow thinking is needed in situations whereby you need to make a decision based on how the situation is.

Base rate neglect: When judging likelihood, we overvalue what “feels” right and undervalue statistics

Here the author states that people value what feels right and undervalue the statistics. This leads to poor decision-making because they fail to analyze the situation and go with what they feel is right.

Sunk costs: we hate the idea of wasting what we’ve already put in

In this section, Kahneman states that people are fond of throwing good money after bad, rather than considering the odds of the investment producing positive results. He says people continue investing in projects with poor prospects that have already consumed a lot of money and resources.

Thinking fast and slow review

Thinking fast and slow is a very intense and engaging book as well. From this book, you will learn a lot about how the human mind works. The book is also very nice for knowing the psychological facts behind economic behaviours. The book is quite a heavy read as it can take longer to read than any other book with a similar number of pages. But it is worth it because you’ll be able to learn about the unconscious biases that we have and attempt to overcome them to make better decisions in life.

Thinking fast and slow audiobook

The thinking fast and slow audiobook is available on google play at $16.95, on apple books at $24.99, and many other audiobook apps.

How do you think slow?

According to Daniel Kahneman’s book “Thinking Fast and Slow“, system 1 of the brain is responsible for thinking slow, this system is lazy and prevents you from using your intelligence, and that’s the reason why you end up making wrong and poor decisions. To become a fast thinker, you need to practice using your brain in situations no matter how simple you think the situation is. Having your brain active all the time helps you become smart, and as a result, you make wise decisions.

How can I develop fast thinking?

Fat thinking is essential in a world that’s always changing. To attain this ability, there are few things you can do, such as:

Reading books on the subject. For example, the Thinking Fast and Slow book by Daniel Kahneman gives you ideas on how you could use your brain to be a quick thinker. Other books that could help you become a fast thinker include A Compendium of Critical Thinking Skills Activities by Marlene Caroselli, and The Power of Thinking Without Thinking by Malcolm Gladwell. Reading these types of books can open up your mind and help you become a fast thinker.

Consult an expert who is a fast thinker and ask for advice on how you can improve your level of thinking.

Practice using your brain in all situations. Don’t allow your brain to go lazy n matter how simple situations may seem. Practice fast thinking whenever you’re faced with a situation that needs your attention, try not to be distracted by things that are not relevant to that particular issue at hand.


Daniel Kahneman thinking fast and slow quotes

Daniel Kahneman has many quotes from the Thinking fast and slow book. Below we have listed some of these quotes:

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

“Our comforting conviction that the world makes sense rests on a secure foundation: our almost unlimited ability to ignore our ignorance.”

“Intelligence is not only the ability to reason, but it is also the ability to find relevant material in memory and to deploy attention when needed.”

“The psychologist, Paul Rozin, an expert on disgust, observed that a single cockroach would completely wreck the appeal of a bowl of cherries, but a cherry will do nothing at all for a bowl of cockroaches.”

“If you care about being thought credible and intelligent, do not use complex language where simpler language will do.”

“The idea that the future is unpredictable is undermined every day by the ease with which the past explained.”

“Odd as it may seem, I am my remembering self, who does my living, is like a stranger to me.”

“This is the essence of intuitive heuristics: when faced with a difficult question, we often answer an easier one instead, usually without noticing the substitution”

“A general “law of least effort” applies to cognitive as well as physical exertion. The law asserts that if there are several ways of achieving the same goal, people will eventually gravitate to the least demanding course of action. In the economy of action, an effort is a cost, and the balance of benefits and costs drives the acquisition of skill. Laziness is built deep in our nature.”

“We are prone to overestimate how much we understand about the world and to underestimate the role of chance in events.”

“I have always believed that scientific research is another domain where a form of optimism is essential to success: I have yet to meet a successful scientist who cannot exaggerate the importance of what he or she is doing, and I believe that someone who lacks a delusional sense of significance will wilt in the face of repeated experiences of multiple small failures and rare successes, the fate of most researchers.”

“A reliable way of making people believe in falsehoods is frequent repetition because familiarity is not easily distinguished from truth.”

“We can be blind to the obvious, and we are also blind to our blindness.”

“The world makes much less sense than you think. The coherence comes mostly from the way your mind works.”

“You are more likely to learn something by finding surprises in your own behaviour than by hearing surprising facts about people in general.”

“The easiest way to increase happiness is to control your use of time. Can you find more time to do the things you enjoy doing?”

“Confidence is a feeling, which reflects the coherence of the information and the cognitive ease of processing it. It is wise to take admissions of uncertainty seriously, but declarations of high confidence mainly tell you that an individual has constructed a coherent story in his mind, not necessarily that the story is true.”

“People tend to assess the relative importance of issues by the ease with which they are retrieved from the memory and this is largely determined by the extent of coverage in the media. Frequently mentioned topics populate the mind even as others slip away from awareness. In turn, what the media choose to report corresponds to their view of what is currently on the public’s mind. It is no accident that authoritarian regimes exert substantial pressure on independent media. Because public interest is most easily aroused by dramatic events and by celebrities, media frenzies are common.”


Thinking Fast and Slow is a book by Daniel Kahneman published in 2011. It is the most gripping book about the human psyche as it critically analyzes the anatomy of human thought, i.e. its rationalities, irrationalities, and presumptions. In a highly polarized world, this book gleams the beacon of new wisdom.

Thinking fast and slow is a fascinating book that can help you know how to use your brain in most situations.

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