Thinking, Fast and Slow

5 minute read


As always, I don’t agree with or use everything I read, but I will still try and summarize it here.If you are new here, read why I put my semi-personal book notes online.

I just absolutely loved this book. The mental models it provides regarding system 1 and system 2 is a very helpful method for explaining the intricacies of the human decision-making process. Understanding this helped me to become more self-aware which allowed me to learn more techniques for becoming a better, more productive, version of myself. Although marked as a book on one of my favorite subjects of “human behaviour”, I think this is a good book for anyone who just wants to understand how others react. You can easily add this to a leadership or startup list.


The author talks about the systems of our mind. System 1 is fast, intuitive, and emotional. System 2 is slow, rational, and logical. Both have their places, it’s important to know the mechanics of each.

Two Systems

It’s normal to think our decisions are directed by system 2 but that’s often not the case. It’s common to think we used our rational analytical “brain” when in fact we used our system 1 brain.

System 1

This is involuntary thinking. If you have read Malcom Gladwell, I would say this is similar to the blink response. This system is not all bad as it seems right now. A skilled engineer may already know what algorithm to implement with just a quick skim of the code. The engineer has seen it so many times it doesn’t require analytical thought.

System 2

This is focused and active thinking. The same skilled engineer may need to analyze a problem he has never seen before to come up with a solution; it’s not an automatic/reflexive action. It also requires more energy and can be exhausting.

Objective Decisions

There are so many cognitive biases intertwined with these explanations I just want to list them all here. We are conditioned to be optimistic, even when being risky. Without calculated risks and reevaluating we won’t be able to properly learn from past mistakes to calibrate to future decisions. This is just as relevant to someone creating a startup or leading a team.

I believe the author gives a couple of examples where subjectivity is important. I agree that it’s important, just not with the examples the author has given. If you know me, you’ll know I reserve the subjectivity for the exploratory part of uncovering a new field/domain/idea, especially when working with other people. After that, I rely on more analytical processes.

External Influences

External factors influence our decision-making process. This is why there is a right time and right place for certain types of conversations as mentioned in various leadership books.

Once again, we could go deep into the realm of cognitive biases. An example the author gives is that of an airplane crash. If you recently read about an airplane crash you may begin to feel (system 1) planes are less safe even though from a system 2 perspective you know they are extremely rare. Overriding your system 1 response with analytical (and ideally, rational) thinking can change the way you book your next flight.

Emotional Influences

Stereotypes, stress, intuition can all impact our decision-making process driven by the system 1 response.

Events with the emotional connection will be the ones we focus on the most. Our associative memory is an important tool in creating our system 1 response. Even the same situation presented in a way to elicit a negative emotional response can have a different outcome. Doctors are more likely to suggest a procedure when the survival rate is 90% than when the mortality rate is 10%.

Path of Least Resistance

Our brains want to have an easy to understand the explanation, even if it is not rational. Doubting something requires a lot of energy consumption. In those situations, most would rather use their low energy consuming system 1 response which presents the information in the best possible way to make it believable.

Daniel says that in anxious individuals the system 2 response is more functional. The “exercise” of constantly analyzing everything makes the additional energy consumption of system 2 seem not as large. Many of us need to encourage the behaviour of expending additional energy to observe facts and ignore feelings.

Intuitions are Useful

Our intuition is still useful, I gave a couple examples above. Specifically, in situations where you are unable to use your system 2 response. Those situations include where a split-second decision must be made. Or where you may have already experienced the exact same situation in the past multiple times. Most of the time we have more than one second to make a decision. So think carefully whether you should be using your system 1 response.

Loss Aversion

Fear of losing something is usually greater than the satisfaction of gaining that same thing. A similar cognitive bias to loss aversion is the “resource effect” that says humans who possess something value that item more. The attachment to the item adds a false value than that what an outside observer would be willing to pay.

Experiences and Memory

The author says we are the combination of two different beings. The experiencing self and the remembering self. We may think that our experience and memory are aligned but that is not the case. Many cognitive biases describe why our memory is not 100% aligned with the situation. The author takes it so far as to say, the experience doesn’t make any difference, only the memory is important. That is, the memory of the experience is what matters. Actively creating faithful memories of your experiences can solve this. Although, I wonder if there is a hack that allows you to create memories that empower you even when the experience doesn’t.


As I mentioned above, this book is great. I think it’s a nice and easy introduction into cognitive biases in a context that applies to those looking to become better leaders and to those who are exploring startups. I generally enjoy Daniel’s works so keep my own cognitive biases (halo effect?) in mind.

Avishaan’s Goodreads

Crucial Conversations: Tools for Talking When Stakes Are High
The Hidden Brain: How Our Unconscious Minds Elect Presidents, Control Markets, Wage Wars, and Save Our Lives
Hello Startup. A Programmer's Guide to Building Products, Technologies, and Teams
How to Win Friends and Influence People
Drive: The Surprising Truth About What Motivates Us
The Systems Mindset: Managing the Machinery of Your Life
Smarter Faster Better: The Secrets of Being Productive in Life and Business
The Five Dysfunctions of a Team: A Leadership Fable
The Pragmatic Programmer: From Journeyman to Master

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