The Great Mental Models · Shane Parrish

First-principles thinking examples

Curated by · reviewed 2026-05-31

First-principles thinking means breaking a problem down to what you know is true and reasoning up from there — instead of copying what everyone already does. Examples:

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5 examples of first-principles thinking

  1. Rocket costs from scratch

    Instead of accepting the going price, ask what a rocket is actually made of (metal, fuel) and rebuild the cost from there.

  2. Cooking without a recipe

    Understanding why each step works lets you adapt freely, instead of blindly following instructions.

  3. Questioning 'best practice'

    Asking 'why do we do it this way?' often reveals the original reason vanished years ago.

  4. Pricing a product

    Build the price up from real costs and value delivered, not from 'what competitors charge.'

  5. Learning a field fast

    Master the handful of core principles and you can derive the rest — instead of memorising a thousand surface facts.

How to spot it in yourself

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