Highlight from The Great Mental Models: General Thinking Concepts

How do you know when you have a circle of competence? Within our circles of competence, we know exactly what we don't know. We are able to make decisions quickly and relatively accurately. We possess detailed knowledge of additional information we might need to make a decision with full understanding, or even what information is unobtainable. We know what is knowable and what is unknowable and can distinguish between the two.