Learning & thinking · a life skill
Advanced Feynman Explanations
one explanation, two listeners, both satisfied
Plain is easy if you're allowed to be wrong. Right is easy if you're allowed to be obscure. Being both is the skill. Write for one newcomer, let an expert mark what's false, have the newcomer say it back, then teach it.
- Challenging to start
- Life-Changing impact
- Learn it in 30 days
- Two listeners, four weeks
The expert
Knows the field. Asked one question: is anything here false? Keeps you right.
The newcomer
Knows nothing of it, and says so. Asked to explain it back. Keeps you clear.
Simplifying alone doesn't get you there: it trades the lecture for the oversimplification. The two listeners pull in different directions, and the corner where both are satisfied is the one worth teaching from.
A four-week rehearsal
Try it now.
One idea from your work, one expert and one newcomer who'll each give you twenty minutes. Each step moves the draft on the square.
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Week 1
Draft it for yourself
The whole explanation, jargon and all, the way you'd tell a colleague. That's the lecture: right, but only for people who know already.
draft 1, in the lecture -
Rewrite it for one newcomer
A real person you can name. Cut every term you can't define in a sentence, and give each idea an example. Expect to overshoot: the simplest version is where mistakes hide.
1 → 2, cut the jargon -
Week 2
The expert test
Ask the expert one question: what here is false? Fix every mark without letting the jargon back in.
2 → 3, the expert's marks -
Week 3
The newcomer test
They read it or hear it, then explain it back to you. Wherever their version goes wrong, yours went unclear first. Rewrite that part and ask again.
3 → explained -
Week 4
Teach it, and log what you can't answer
A talk, a lesson, a write-up other people will use. Write down every question you couldn't answer on the spot. That list is where your understanding ends, and where the next round starts.
explained, out in the world
One idea, three drafts
Why raising rates slows prices.
The same idea at each stop on the square. Draft 2 is the one people skip past: simpler than draft 1, and wrong.
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Draft 1 the lecture
Raising the policy rate tightens financial conditions and dampens aggregate demand, easing inflationary pressure.
Right, but a newcomer stops at “policy rate”.
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Draft 2 oversimplified
The central bank makes things more expensive, so people stop buying them.
Easy, and wrong: the bank doesn't set prices. The expert marked it.
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Draft 3 explained
When the central bank raises its rate, loans and mortgages cost more, so people and firms borrow and spend less. With less money chasing the same goods, prices rise more slowly.
The newcomer said it back: “borrowing costs more, people buy less, shops can't keep raising prices.”
Why you need a listener
The tune in your head.
3 of 120
songs named. The tappers had expected about half.
In 1990 Elizabeth Newton, a Stanford graduate student, had one person tap out well-known songs, “Happy Birthday” among them, while another listened and guessed. Before they started, the tappers guessed the listeners would name about half. Of 120 songs tapped, the listeners named three.
The tappers heard the tune in their heads as they tapped. The listeners heard knocking. Once you know something, you can't easily hear it as someone who doesn't, which economists had named the curse of knowledge a year before. An expert explaining is the tapper. Only a real listener tells you what came across.
The idea
Why it works.
The physicist David Goodstein once asked Richard Feynman to prepare a freshman lecture on a hard point of quantum physics. A few days later Feynman came back. “I couldn't do it,” he said. “I couldn't reduce it to the freshman level. That means we really don't understand it.”
He wasn't saying everything should be made simple. He was using the freshman as a test: if he couldn't reach one without saying something false, he didn't yet know it well enough. The expert keeps the explanation honest and the newcomer keeps it clear. Feynman put the rule plainly in a 1974 talk: “The first principle is that you must not fool yourself — and you are the easiest person to fool.”
Keep it honest
Use both listeners.
- Pick a newcomer who interrupts. Politeness hides the place they got lost.
- Ask the expert what's false, not what's missing. Missing is endless. False is a list you can fix.
- Keep the question log. One line a question, with the date. It's your next month's reading.
- Teach it again in a month. If the log has shrunk, you've learned it, not just written it.
Go deeper
Keep going.
- Simple Feynman Explanations
- Deliberate Feynman Explanations
- Advanced Feynman Explanations
Keep this going in the app.
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