Your brain runs two parallel systems: one fast and automatic, one slow and deliberate. Most of your decisions are made by the wrong one.
What does this mean to me?
In practice
For the next week, before making any significant decision, pause and ask: which system is driving this? If it feels obvious and easy, System 1 is probably in charge. The feeling of certainty is not evidence of correctness – it's often evidence that you're not thinking hard enough.
Reflect
Think of a recent decision that felt obvious and certain. Was System 1 driving it – or System 2?
Cognitive biases are not quirks or exceptions. They are the default operating mode of the human brain.
What does this mean to me?
In practice
Before your next important decision, write down the three most likely cognitive biases that could be distorting your thinking. Anchoring: have you been influenced by the first number or idea you heard? Confirmation: are you mainly looking for evidence that supports what you already think? Availabili...
Reflect
Which cognitive bias do you think affects your decisions most? Anchoring, availability, or confirmation bias?
We are not rational about gains and losses. Losing €100 feels roughly twice as bad as gaining €100 feels good. This asymmetry drives most bad financial decisions.
What does this mean to me?
In practice
Review a recent decision you avoided making. Was the avoidance rational, or was it driven by loss aversion? Specifically: did you avoid a decision because the potential loss felt unbearable, even though the expected value was positive? Loss aversion often masquerades as prudence.
Reflect
Think of a risk you've been avoiding. Is the avoidance rational – or driven by loss aversion?
Overconfidence is the most pervasive and damaging cognitive bias. Experts are not immune – often they are more overconfident, not less.
What does this mean to me?
In practice
For your next prediction or estimate, give a confidence interval rather than a single number. Instead of 'this will take 3 weeks', say 'I think this will take between 2 and 6 weeks, with 3 weeks being my best guess.' Then track your actual accuracy over time. Most people discover their confidence in...
Reflect
Think of your last confident prediction. How accurate was it? Did you track it?
Humans are story-making machines. We create coherent narratives from random events and then mistake the story for reality.
What does this mean to me?
In practice
Think of a significant success or failure in your life. Write down the story you tell about why it happened. Then ask: how much of this was genuinely caused by the factors I'm identifying? What role did luck, timing, or factors outside my control play? Honest accounting of randomness is one of the m...
Reflect
Think of a success or failure you've explained with a neat story. How much was actually luck?
The self that lives your life and the self that remembers it are not the same. We optimise for memory at the expense of experience.
What does this mean to me?
In practice
Plan your next significant experience – a holiday, a project, a difficult conversation – with both selves in mind. What would make the experience better while it's happening? What ending would make it remembered most positively? These are often different design problems.
Reflect
When did you last plan something that took twice as long as expected? Did you update your future estimates?
You cannot eliminate cognitive biases. But you can build systems that catch them before they cause damage.
What does this mean to me?
In practice
Before your next major decision, run a pre-mortem: assume it has gone badly, and write down the three most likely reasons why. This is not pessimism – it is System 2 doing the work that System 1 wants to skip. The goal is not to talk yourself out of the decision, but to stress-test it honestly.
Reflect
What decision are you facing now where a pre-mortem would be most useful?
Before you decide
"When did you last make a confident decision that turned out to be wrong – and what did you learn from it?"
The idea that hit me most
What I will do differently this week
Will I buy this book? Why / why not?