Thinking method · Munger, via Parrish, Clear Thinking

Mark the edge of what you know

Naming where your competence ends, so you can behave differently outside it. Any decision in a domain you are not trained in.

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Naming where your competence ends, so you can behave differently outside it.

The steps

1. List what you genuinely know well enough to judge without help.
2. List what you know a little about — enough to be dangerous.
3. Mark the boundary explicitly.
4. Outside it, change behaviour: ask, defer, take smaller positions, or stay out.
5. Revisit the boundary periodically. It moves, in both directions.

When to use it

Any decision in a domain you are not trained in.

What it will not do

The edge is exactly where you are worst at seeing it. Other people can often see yours.

Where it comes from: Munger, via Parrish, Clear Thinking. Described in our own words.