You probably had this book recommended to you a hundred times. This is going to be a 101st.
As usual, the book title is a bit misleading. It’s not about thinking fast like a Sherlock or being a slowpoke. The main idea is that there are two types of thinking. There is an automatic intuitive thinking which is pretty fast (System 1). The slow thinking is the deliberate effortful thinking (System 2).
The book is very easy to read. It introduces various concepts such as biases that are illustrated using understandable examples from daily life. I really like that arguments are supported by research.
Biases are mind-blowing!

I don’t want to spoil too much but there is so much I’ve learned from the book!:
- Expert predictions are worse than a dice roll because they are overconfident in their intuitive predictions. Formulas based on a few key factors are more consistent. Example: Predicting a future price of wine based on weather parameters.
- Investment fund managers can’t consistently beat the market. If a fund does well, it’s just luck. It will run out. In other words: regression to mean.
- Praising players after a great match or giving them hard time after a failure. If they did really badly their score was way below average. And at that point you feel they need a lesson. They will probably improve in the next match with or without your scolding. It’s all about regression to mean.
- Good way to estimate is to start with a base rate and then adjust from it towards our intuitive guess by the % amount of correlation. Say, the average number of something (base rate) is 1000. The evidence you have produces an intuitive answer in your mind: 2000. Correlation of evidence and the number is about 30%. To get your final estimate, move 30% from 1000 towards 2000 so 1300.
- When estimating a frequency of something our intuitive thinking swaps the question of frequency for the question of ease of recall and we don’t even notice!
- If environment provides opportunities to practice a skill by providing timely feedback and is stable enough we can trust experts short-term prediction. Like a firefighter who just knows it’s time to evacuate the room (a few seconds later ceiling collapses).
- Priming for slow walking by doing a word puzzle involving old-age-related keywords such as “wrinkle”.
- Ego depletion is a drop of glucose in blood.
- Hard to read text produces cognitive strain and mobilizes system 2 which helps to reject intuitive ideas produced by system 1. Frowning does also mobilize system 2.
- Busy system 2 makes us more gullible.
- Same input can be evaluated by system 1 as a different thing based on the context (“B” and “13”):
