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Think and Reason Join

5 moves, one chain

The five moves

A plain method for thinking from first principles. Use it on a claim, a plan or any answer handed to you.

Start at move 1
A cut-away of the ground, drawn in lines. A stack of books stands on loose fill over a footing nobody checked. A stair goes down through rock to bedrock. A new column rises from there and takes a load. Drawn as a construction in code, no image model. (c) FNU Ratnavarma @notebook.beer Ground Rock Bedrock
Each number marks one move on the drawing.
  1. Name the claim
  2. Find the assumption
  3. Ask why until it stops
  4. Rebuild from what is certain
  5. Test what breaks
Drawn in code, no image model · (c) FNU Ratnavarma @notebook.beer · How this site was made

  1. 01 / 05

    Name the claim

    Write the claim as one sentence that could be wrong.

    Move 1 · Name the claim · 10 seconds

    What exactly is being said?

    Go deeper into Name the claim

    Most arguments start fuzzy. A school is better. A diet works. Those phrases hide the claim. Write one sentence that could be false.

    From daily work

    Someone says the new school is better. I ask what that claims. It becomes: more of its pupils pass maths than ours do.

    Try it slowly

    Pick one claim you heard today. Write it as a single sentence that could be proven wrong.

  2. 02 / 05

    Find the assumption

    List what must be true for the claim to hold.

    Move 2 · Find the assumption · 10 seconds

    What must be true for this to hold?

    Go deeper into Find the assumption

    Every claim rests on things nobody said. List what must be true for it to hold. Mark each known, believed or guessed. Guesses carry risk.

    From daily work

    An estimate says the job takes four weeks. It assumes clean data, the same two people and nobody pulled away. None was checked. Two were guesses.

    Try it slowly

    Take your claim from move one. Write three things that must be true for it to hold. Mark each as known, believed or guessed.

  3. 03 / 05

    Ask why until it stops

    Keep asking why until you reach something you can measure.

    Move 3 · Ask why until it stops · 10 seconds

    Why is that so? Then why is that?

    Go deeper into Ask why until it stops

    One why gives a reason. A chain gives a cause. Stop at something you can check, or at a preference. Never at 'everyone knows'.

    From daily work

    My rent rose 200 dollars. Why? Costs rose. Why? Building insurance doubled. Why? Two floods in the county. The rent was never the story.

    Try it slowly

    Choose one number you saw this week, in a bill or a headline. Ask why it moved, in writing, until it stops.

  4. 04 / 05

    Rebuild from what is certain

    Keep only what you have checked. Build upward from there.

    Move 4 · Rebuild from what is certain · 10 seconds

    What do I know for sure? What follows?

    Go deeper into Rebuild from what is certain

    Set borrowed conclusions aside. Keep only what you checked yourself. Build upward one step at a time. Mark any 'probably'. Now you know why.

    From daily work

    A box says high in fibre. I drop the phrase. Grams per serving, serving size, what I pour. My bowl gives less than claimed.

    Try it slowly

    Write down three facts about your problem that you have checked yourself. Build one conclusion from only those.

  5. 05 / 05

    Test what breaks

    Look for the weak joint. Try the cheapest test.

    Move 5 · Test what breaks · 10 seconds

    If this is wrong, where does it fail first?

    Go deeper into Test what breaks

    A good idea survives attack. Find the weak joint. Ask what would change your mind. Try the cheapest test. An untestable claim is a belief.

    From daily work

    A post says a new mattress fixed back pain. I ask what breaks. They also began stretching daily. The mattress may not be the cause.

    Try it slowly

    Finish this sentence about your claim: I would change my mind if I saw this. Then go and look for it.

  6. And again.

    Each answer is a new claim. Take it back to move 1.

Go deeper: the five moves with any tool

Using the five moves with any tool

A search box, a textbook, a friend who knows or a chat window. Each is a fast partner. None replaces your own reasoning.

The risk is not a bad answer. The risk is that you stop asking.

Do the first two moves yourself. Write the claim and your assumptions before you open anything. Then bring them to the tool.

You will ask better questions. You will also notice when the answer slides past what you asked.

Ask the tool two things. First, why this is true. Make it show the chain step by step. Check each step against something you know.

Second, what breaks if this is wrong. Ask it to name the weakest assumption. Ask for the cheapest test. Then run that test yourself.

Close the tool. Do move four alone. Rebuild the answer from what you can verify. Where the two differ, there is something to learn.

A few habits keep the thinking yours:

  • Ask for the reasoning, not only the result.
  • Ask it to argue against its own answer.
  • Treat every number it gives as a claim to check.
  • Write your conclusion before you read its conclusion.

Any tool can speed up each move. None can do the moves for you.

Notebook

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