A mental model is a simplified picture of how something works. The useful ones travel: an idea from economics or mathematics that, once learned, shows up in every decision you make. Charlie Munger called a set of them a latticework.
8 ARTICLES110 MIN OF READINGREVIEWED NOV 2026
THE LATTICEWORK IN THIS TOPIC
A model is only as good as your sense of when to put it down. Each card says when to reach for it and how it fails.
SECOND-ORDER THINKING
First-order thinking stops at the immediate effect. Second-order thinking follows how people and systems respond. Colonial Hanoi paid a bounty per rat tail; people cut tails off and bred the rats.
Read: Second-Order Thinking
INVERSION
Instead of asking how to succeed, ask what would guarantee failure and avoid that. Gary Klein’s premortem asks a team to assume the project already failed and explain why.
Read: Inversion
OCCAM’S RAZOR
Between explanations that fit the facts, favour the one that needs fewer assumptions. Each extra assumption is another chance to be wrong.
Read: Occam’s Razor
HANLON & CHESTERTON
Hanlon: do not assume malice where error explains it. Chesterton: do not tear down a fence until you know why it was put up.
Read: The Three Razors
FIRST PRINCIPLES
Strip a problem to constraints that cannot be reduced further and reason up. Battery packs were priced near $600/kWh while the raw materials cost about $80.
MAP VS. TERRITORY
A map is useful because of what it omits. Models fail through omission, bias or staleness, and adding detail rarely fixes a model that misled you.
WORKED EXAMPLE
Your biggest customer asks for a custom feature. Should you build it?
FIRST-ORDER VIEW
“Yes. They are our largest account and it keeps them happy.”
SECOND-ORDER
Other customers ask for their own exceptions; the roadmap fills with one-off work; the product gets harder to sell to everyone else.
INVERSION
What would guarantee we lose this customer? Ignoring the problem behind the request. That is different from building their exact feature.
OCCAM’S RAZOR
The simplest explanation for the request: an underlying workflow gap others probably share. Test that before building anything.
DECISION Solve the underlying problem in a way that works for every customer, and tell the big one why. Models did not make the call; they surfaced what the first answer missed.
Biases are why the first answer felt so obvious: Cognitive Biases Everyone Falls For. Choosing between lenses: First Principles vs Systems Thinking.
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Want one of these covered first? Suggest a topic.
A simplified representation of how something works, used to reason about situations you haven't seen before.
A handful understood deeply beats a long list. Start with second-order thinking, inversion and first principles.
Biases are the failure modes models are meant to correct, knowing them tells you when to reach for a model.
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