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LESSON 5 · The Mental Models Playbook

The Circle of Competence

Warren Buffett and Charlie Munger popularized the circle of competence: the areas where you have genuine knowledge and proven judgment.

Brilliant people make terrible decisions in unfamiliar domains every day. A world-class cardiologist has no special insight into cryptocurrency markets. A legendary investor has no medical expertise. Raw intelligence does not fill the gap — without real experience in a field, even a sharp mind is working blind.