Thinking, Fast & Slow
An ongoing inquiry · No. 01 EN·
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An essay on two minds

Thinking, fast & slow.

Inside every decision you make, two systems are arguing. One is quick, instinctive, and almost always wrong about probability. The other is deliberate, effortful, and easily exhausted. The interesting question is no longer which one you should trust — it's what happens now that machines have learned to do both.

SubjectCognition · Decision-making
Reading time~ 4 minutes
Updated2026

System One

The Intuitive

— effortless, automatic, always running.

  • Recognises a friend's face01
  • Reads a billboard from a moving car02
  • Detects anger in a voice03
  • Completes the phrase "bread and …"04
  • Drives a familiar route05
  • Answers 2 + 206
System Two

The Deliberate

— effortful, slow, the self you believe you are.

  • Counts the F's in this sentence01
  • Parks in a tight space02
  • Compares two washing machines03
  • Fills out a tax form04
  • Holds an unfamiliar argument05
  • Multiplies 17 × 2406

We are blind to our own blindness. We have very little idea of how little we know.
— On the limits of introspection

A short field guide to your own mistakes.

Six of many
№ 01 / Anchoring

The first number wins.

Whatever value enters your head first quietly drags every estimate after it toward itself — even when you know the number is irrelevant.

№ 02 / Availability

What comes to mind feels true.

Vivid, recent, or emotional examples are mistaken for common ones. Plane crashes feel more frequent than car accidents.

№ 03 / Loss Aversion

Losing $100 hurts twice as much as winning $100.

We will take strange risks to avoid a small loss, and refuse fair bets that would, in aggregate, make us richer.

№ 04 / Substitution

You answered an easier question.

Asked something hard, the mind quietly swaps it for a question it can answer — and presents the answer as if it were the original.

№ 05 / Halo Effect

One trait colours every other.

An attractive speaker seems smarter; a confident CEO seems more competent. The first impression rents the rest of the room.

№ 06 / Hindsight

Of course it happened.

After the fact, the world feels inevitable. We rewrite our prior beliefs to match what we now know — and learn the wrong lessons.

Postscript · 2026

And now there is a third system in the room.

A large language model is, in a strange way, the first artefact in human history that does both fast and slow thinking — pattern-matching at the speed of intuition, then reasoning at the pace of deliberation. It inherits our biases because it learned from us. It introduces new ones because it isn't us.

The original question of the book was: when can you trust your intuitions? The new question is harder: when can you trust someone else's, scaled to a billion users?