Thinking Fast and Slow Summary – Daniel Kahneman book on cognitive dissonance

Within every person’s brain, there are two systems consistently at work to remain in control over your actions and behaviors. Thinking Fast and Slow by Daniel Kahneman depicts these two systems to their fullest extent, as well as many other factors that influence your decision-making process, your biases, and much more.

Kahneman presents this information in a way that allows you to absorb it and effectively apply it to areas of your ways of thinking. In this blog post we summarize the most important concepts and ideas from the book, Thinking Fast and Slow.

Summary of Thinking Fast and Slow

A psychologist by training, Daniel Kahneman also holds the title of Nobel Laureate in Economics. The prize was majorly won for his work in the field of decision making, specifically the ‘Prospect Theory’. This book very much encapsulates his work on human thinking; showing your inherent cognitive biases, the limitations of your mind, but also its sheer brilliance and capabilities.

Thinking Fast and Slow Summary - By Daniel Kahneman

As stated previously, Kahneman takes this book as an opportunity to explain these two systems that exist within your brain. The first system is described as both automatic and effortless, but also incredibly impulsive. The second system is described as being more consciously aware, deeply considerate, and thorough.

Best ideas and concepts from Thinking Fast and Slow

System One

System one being automatic and intuitive, helps you perform the majority of the cognitive tasks that your day-to-day life requires. This can include things like navigating a familiar drive home, recognizing family and friends, identifying threats, generating feelings, etc. This system is very primitive in a sense and is described as crucial for your well-being.

Being your innate system, system one is your filter for how you’ll interpret your everyday experiences. That being said, there are moments where actions that occur through system one, can meld into system two. This happens when you become consciously aware of or engage with an action. For example; breathing would fall under system one, however, when you become aware of your breathing and attempt to self-regulate it, it falls under system two.

System Two

System two having greater awareness and thought process, helps you to analyze life’s most complex problems. This can include things like completing long math equations, parallel parking in an unfamiliar space, complex logic reasoning, crossword or sudoku puzzles, etc. While highly analytical, this system can also be quite time-consuming, requiring effort and energy.

System two is the younger of the two systems, holding keen importance in your life as you continuously adapt to modernizations and changes in your priorities, health, etc. Kahneman makes a point to say that you ought to tap into this system more often, as it can hold a helpful authority over system one if you train it to. For example; the initial detection of a person is generally associated with system one, however, you can allow it to work better by using system two to search for a specific person in a crowd. This allows for the system to perform better and is similar to the process you’d utilize while doing a word search puzzle.


In the second half of Thinking Fast and Slow, Kahneman introduces you to the topic of ‘heuristics’. Heuristics is essentially mental shortcuts you take while in the decision-making process. Considering humans are consistently trying to solve problems as quickly as possible, heuristics are generally very helpful in your daily life.

Heuristics can help you to apply previous situations knowledge, to a present circumstantial problem. However, heuristics can also cause systemic errors in thinking, misinterpretation of events, severe cognitive biases, and just generalized poor decision making.

Kahneman continues in further depths about specific heuristics that can lead to poor decisions such as; anchoring (depending heavily on preexisting information), cognitive ease (whatever is easier for system two to believe, will likely be believed), jumping to conclusions (based on system one), and more.

Risk/Loss Aversion

Another major topic that Kahneman touches on in this book is risk aversion and loss aversion. He notes that in general humans tend to be risk-averse, meaning you attempt to avoid risk at all costs out of fear of the worst outcome. A risk-averse decision-maker will choose to pay the price to avoid the inevitable uncertainty.

Loss aversion, on the other hand, deals with the concept that you are likely more strongly driven to avoid potential losses than you are to strive for gains. Because of this, you often adopt short-term goals to achieve, but not necessarily surpass, and are equally likely to reduce your drive once they’re reached.

Memories/Preferences Shaping Decisions

The last major topic to touch on that Kahneman discusses is that of how preferences and memories affect your decision-making process. Kahneman says that as humans, you generally believe that your decisions have your best interest at heart, but this isn’t always the case. You can’t fully trust in the fact that your personal preferences will always lead you towards the greatest possible outcome.

Similarly, memories also intrinsically affect your decision-making process, however, with the negative aspect that your memories can be flawed or just downright incorrect. Generally, you hold less memory towards something painful and greater memories of moments of happiness. While seemingly harmless, Kahneman urges you to realize this isn’t proper.

Who Should/Shouldn’t Read Thinking Fast and Slow

I believe that this is an excellent read for anyone who may be under the impression that they have some decision-making flaws. I tend to be a ‘fast thinker’, always rushing to conclusions and utilizing my emotions negatively, and I found this book to be quite helpful with that. If you struggle with judgement or decision-making, I highly recommend this book!

However, if you’re closed off to the idea of learning how to better deal with your decision-making or thought process, then this may not be the book for you. It also may not be for the folks who are just genuinely uninterested in the topics of human behavior or psychology.

Review of Thinking Fast and Slow by Daniel Kahneman

I genuinely enjoyed reading Thinking Fast and Slow. I found that this book being written by such an acclaimed psychologist to be immediately reassuring in the sense that I knew the information was going to be factual and valid. I also found the information to be incredibly applicable to my own life. As previously stated, I tend to be a fast-paced and emotional thinker and this book offered insight on why that is, and how I can go about working on it.

I think this book is excellent for any fellow open-minded individual that may be interested in this subject matter or possibly self-betterment. However, as I’ve also previously mentioned I could see how this book could come across as ‘boring’ to someone without interest in the topic.

Overview of Thinking Fast and Slow

In conclusion, I believe Thinking Fast and Slow by Daniel Kahneman is an incredibly well-written book, that is more than worthwhile to read. If you can even find one aspect of this book that can apply to bettering your overall thought process, then I think Kahneman accomplished what he set out to do with this book. I highly recommend taking the time to read this one!

Marilyn Nissen
Written by Marilyn Nissen

Marilyn Nissen is the founder of, a highly reputable book summary and reviews website. With over a decade of experience in summarizing and reviewing books, Marilyn is a trusted authority in the book industry.