The circle of competence is the domain where your knowledge is deep enough that your judgment can actually be trusted. Parrish and Beaubien argue the important thing isn’t how big your circle is — it’s knowing exactly where its edges are. Someone with a narrow but well-mapped circle will outperform someone with a broad, fuzzy one, because the second person keeps wandering outside it without noticing. Building a circle takes sustained experience, honest feedback, and a willingness to track your own mistakes. Maintaining it takes ongoing effort, since knowledge decays and fields change. Outside your circle, the recommended moves are: learn enough of the basics to ask decent questions, borrow from people whose circle covers that territory, and be skeptical of confidence that isn’t backed by experience.
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