Thinking Fast and Slow by Daniel Kahneman is a book about how humans think and rationalize the world around them. It touches upon the subtle, and sometimes unnoticed, factors that influence our decision making. It is backed by decades of research and studies conducted by Dr. Kahneman and his close colleague, Amos Tversky. Kahneman also uses interactive examples to illustrate his points to the reader, some of which I found very interesting. They were effective ways of proving a lot of the concepts and explanations that are introduced throughout the book.

Overall, Thinking Fast and Slow was an engaging book that doesn't get too bogged down in details, while also being thorough enough to get new concepts across to the reader. Kahneman uses simple metaphors and examples to show that we may not have as much control over how we think and arrive at decisions as we feel we do. I thought about what I was reading even while I was not reading it, and when I felt strongly about an opinion or a decision I was making I started to self-reflect on the factors that might be influencing my feeling. That to me is a sign of a great non-fiction book: a book that, in its attempt to explain some aspect of the world around you, actually changes how you perceive the world, and it adds to the context of your living experience in a noticeable way.

I will try to briefly summarize the main sticking points of Thinking Fast and Slow. Very early on, Kahneman introduces the concept of partition within our brain's structure. Or it may be more correct to say our mind's structure as the actual partition most likely does not have any physical manifestation, it is more of a tool to think about the different systems at work within our consciousness.  Kahneman asserts that these systems have identifiable characteristics, as well as physical changes which signify their level of activity at that moment. There are two major "systems" that compose our consciousness, and they are engaged in a constant dialogue to determine who best to handle a particular task. Kahneman refers to them as System 1 and System 2; System 1 is the system that is primarily in charge of acting as your consciousness, in the sense that as you process your everyday sensual experience, you are processing this stimuli with System 1, and System 1 is what offers up the relevant ideas and thoughts that float across your mind as this happens.

Thinking, Fast and Slow cover

For the most part, our waking hours are primarily composed of this state of mind. Most decisions we make and actions we take do not invoke much strain on our mental resources. Only when we require increased focus on a particular task do we need to invoke "System 2" according to Kahneman.  System 2 is in charge of of anything we would consider "thinking hard", like math problems, memorizing things, trying to speak another language, or even things like being in an unfamiliar and potentially dangerous situation. What all these have in common is that they require heightened focus and awareness because we place importance on "succeeding" in whatever the task or situation is. We need to invoke System 2 in order to work through things logically and rationally, as well as to remember and form new patterns based on some sensory data.

If our brains were computers, I would liken System 1 to being a browser cache that stores previous answers to tasks we've seen. If our brain encounters a scenario that it has seen before, which is most of what we do every day, it simply checks whether it has seen this question or situation before, and if it has it will return that "answer" and use it. However, if a computer encounters a request it hasn't processed before, it has to call a more expensive procedure in order to retrieve the desired information. This could take the form of a request for a webpage, where the computer will now have to send the request out to the internet which will be expensive in time, or it could be a database query that will be end up being more expensive with computational cycles. Whatever the case, computers would not be as useful or as fast as they are today without a concept like caching.

The reason both our brains and computers have a mechanism like this is that both are lazy and strive to optimize things. If we repeatedly encounter the same situations every day that requires us to carry out some series of tasks, whether they are physical like brushing your teeth or mental like counting change, we naturally form mental automations which allow us to do these tasks without wasting mental resources. A common term for this is "muscle memory" and if you accept that your brain is a muscle then I think it is an apt term to describe the mechanism. I believe the formation of this cognitive layer of abstraction is what Kahneman calls System 1, and I also believe it is a fundamental component of what gives humans their sentience. We have the ability to call these "modules" without worrying about their details, and therefore our brains can conserve its energy for when we feel the need to focus on something new or important.

Basically, the rest of the book is Kahneman providing examples and reasons why our System 1 cannot be trusted a lot of the time, and the myriad of factors which can influence the answers System 1 provides without us knowing of those influences.I'm going to now share a few quotes I found especially interesting or poignant in Thinking Fast and Slow, and I will briefly expound on them.

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The psychologist Mihaly Csikszentmihalyi (pronounced six-cent-mihaly) has done more than anyone else to study this state of effortless attending, and the name he proposed for it, flow, has become part of the language. People who experience flow describe it as “a state of effortless concentration so deep that they lose their sense of time, of themselves, of their problems,” and their descriptions of the joy of that state are so compelling that Csikszentmihalyi has called it an “optimal experience.”

— Daniel Kahneman, "Thinking, Fast and Slow" pg. 70

 I thought this was a great description for a feeling that I have thought a lot about before, and one that I love to experience. When you are working on a task that combines a difficultly level perfectly with your existing level of proficiency, you experience this "flow" as you work towards the solution or completion of the task. In order for the experience to be truly fulfilling, it has to be challenging enough to command your full focus, but you also have to be confident in your capability (from past experience and learning) to complete the task at hand. In my head, I sort of see it as being able to see the rough outline of the solution and the path you must take, but still not yet having figured out the details. Having this finite path in your mind is what evokes the sense of "timelessness" as you work, because you are only concerned with the completion of each individual step along the path, and have already committed yourself to doing so.

The place in my life I have experienced this most commonly has been during school, when working on problems in math and physics. Working out the solution to a lengthly question, especially when in a time-constrained environment like an exam, can provide a very concentrated feeling of happiness to me as I work towards a successful answer. It is a very powerful force, and I strive to find this feeling in any aspect of my life.

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The only difference between the two groups was that the students conceded that they were influenced by the anchor, while the professionals denied that influence.

— Kahneman, pg. 233

This insight was the result of a study Kahneman conducted on the influence of "anchoring effects" when people are evaluating something's worth. In this example, it was whether the awareness of a home's asking price was an "anchor value" when asked to determine the value of the home itself. Kahneman asked both amateurs (students) as well as real-estate professionals to conduct the test, and the results indicated that for both groups, those who were told the seller's asking price initially we're influenced by it as an anchor value. What this really means is that their answers were clustered around this value in a statistically significant way, whereas those who were not told the asking price of the home had far more evenly distributed (or maybe distributed around a different value) estimates for the home's true value.

I think the implications of this finding aren't anything shocking; I think its somewhat intuitively known that it will factor into our answer. But it is obviously a useful effect to know about, especially when conducting negotiations. But I think the more interesting finding is what is mentioned in the quote: the fact that those who are the "experts" at the evaluation are still influenced by the value - which proves they are not truly objectively determining the value. I think it says something about the nature of professional opinion - you have to believe in yourself in order to inject value into your opinion.

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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 thefts by teenagers are 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.

— Kahneman, pg. 246

Much of the book Kahneman devotes to explaining the biases that can affect our judgment. One bias in particular Kahneman highlights is called the availability bias. Essentially, when evaluating the likelihood of an event occurring, our answer will be influenced by how easily we are able to recollect past examples of the event occurring in our lives, or even just instances of similar events. The examples provided in the quoted text illustrate this concept well.  You will assess the significance of a problem such as neighbourhood crime much higher if your next-door neighbour had their car broken into last week. Or similarly if you cannot recall any of your friends or family having the flu for the past several years, you will be less likely to be concerned with getting your flu shot due to the seeming absence of a threat to your health.

I would assume that this concept would be rather intuitive, and possibly already evident to those who have never read Kahneman's work, but it is interesting to read about this effect and how its been witnessed in controlled studies. Even in the presence of objective information and statistics concerning the event in question, people still err towards their personal experiences and memory in determining its likelihood. 

If nothing else, it is important to understand these biases as best as possible, so that you may be able to mitigate their effect on important decisions you make. I personally strive to be as rational as I can in my decision-making.

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This stark version of the problem made Linda famous in some circles, and it earned us years of controversy. About 85% to 90% of undergraduates at several major universities chose the second option, contrary to logic. Remarkably, the sinners seemed to have no shame. When I asked my large undergraduate class in some indignation, “Do you realize that you have violated an elementary logical rule?” someone in the back row shouted, “So what?” and a graduate student who made the same error explained herself by saying, “I thought you just asked for my opinion.”

— Kahneman, pg. 294

The Linda problem that Kahneman describes is quite ingenious, and almost humorous in how it will trip up even those that are educated in statistics and probability. I highlighted this passage in particular because I found it rather poignant, despite the bluntness of the graduate student who shouted out from the crowd. Even though I think Kahneman meant for this interaction to be viewed as some light-hearted humour, I think it serves as a valid contradictive voice in this discussion of the significance of Kahneman's findings.

Kahneman's entire field of study is based on decision making, which he attempts to describe using his Prospect Theory, which is a theory of human rationality that attempts to predict how humans actually make decisions in real life. With that in mind, you could argue that trying to prove the validity of the theory using controlled studies - which primarily are composed of asking participants hypothetical questions about hypothetical scenarios - is in a way self-contradictory. 

I believe that studies of human nature may suffer from some intrinsic quality that prevents them from ever truly reproducing actual human nature. Much like how a photon behaves differently when it is under observation, I think humans are not completely unaffected by the context with which a question is presented to them. 

In my opinion, the rhetorical "So What?" the graduate student shouted back at Kahneman after he pointed out the logical inconsistency with the students' responses, can be viewed as a realist perspective on the over-analysis of humans. In different settings and in different contexts, perhaps most people would answer the Linda problem correctly. What are we truly gaining from the results of these studies, and can we really say we understand humans better because of them?

That will conclude the critical portion of this book review. 

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— Kahneman, pg. 296

What a great word! 

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As predicted by denominator neglect, low-probability events are much more heavily weighted when described in terms of relative frequencies (how many) than when stated in more abstract terms of “chances,” “risk,” or “probability” (how likely). As we have seen, System 1 is much better at dealing with individuals than categories.

— Kahneman, pg. 627

Denominator neglect is a type of phenomenon Kahneman attaches to instances where humans will weight low probabilities much higher in their minds then their true likelihood deserves, especially when the event in question is a negative outcome. Essentially, when discussing outcomes to any particular event or situation, the act of just including some low probability outcome in the discussion will inadvertently increase its apparent likelihood within the minds of those discussing it. In other words, bringing up the fact that a certain outcome could possibly occur will put it in the realm of possibilities and therefore will be given equal footing with all other possibilities in terms of your attention.

For example, if you require surgery on your eyes, and the doctor tells you there is 5% chance (which itself might be a gross exaggeration) there will be complications and your eyesight will be impaired, then all you will be able to think about is that improbable event and you will not be comforted much by the 95% chance everything will be fine.

Or alternatively, imagine there is a bug spray on the market available which clinical studies have shown has a small chance (<1%) of causing a severe rash in children. There is another premium bug spray available which has no such side-effects associated with it. Kahneman has shown that parents, when presented with the choice between both bug sprays, have been willing to pay significantly more in order to buy the premium bug spray, despite the extremely low probabilty of any actual rash developing on their child. 

Another interesting and related discovery was what the quote above was mentioning. Humans seem to be worse with denominator neglect when probabilities are presented to them in the form of relative frequencies i.e. 1 in 1000 cases. What Kahneman believes is that since people are more comfortable with thinking of whole numbers, it is easier to think about what 1 out of 1000 looks like in terms of scale. Moreso it is also easier to imagine yourself, or your child, as being that 1 case out of however many. That's why when performing a study like the aforementioned bug spray example - there is a significant difference in responses depending on how the probability is framed. If the bug spray causes a rash in 1 in 1000 children, parents will be more averse to buying it compared to stating it causes a rash in 0.001% of children. Just another example of many such idiosyncrasies found within human reasoning.

All in all, I thought this was a intriguing book on a very peculiar topic - the mind. Reading, and thinking, about the way one thinks is definitely a strange concept, as it can lead down winding and recursive lines of thought the more you think about it. However, I think Kahneman has done a great job with unraveling some of the processes that affect our consciousness. Trying to understand a little better how we rationalize and make decisions is a valuable endeavor; I think anyone that seeks a deeper understanding of their personal judgment will become a better decision maker. Removing internal biases allows one to see the world around them, and their place within it, more clearly. In any case, I was definitely more engaged and in tune with my thoughts and feelings while reading this book, and I hope to remember some of the lessons and insights and carry them forward in life. I can't ask for much more in a book.