Know and mark the edges of your circle
Label the boundary clearly: 'inside my circle’ vs 'outside my circle’ vs 'I am not sure.'
Key takeaways
- What it is: Label the boundary clearly: 'inside my circle’ vs 'outside my circle’ vs 'I am not sure.'
- Why it works: An unmapped edge is invisible and therefore crossable without warning. Explicitly marking the boundary — "I know retail banking well; commercial real estate I only know the surface of" — creates a cognitive speed bump before decisions in adjacent territory. The edge is where confidence is highest and accuracy is most likely to have diverged, making it the most dangerous point in the circle.
- Evidence: Backed by observational / correlational evidence.
- Avoid: Treating the edge as a gradient to push rather than a boundary to mark — continually rationalizing why the adjacent area is "close enough" to your core domain.
Why it works
An unmapped edge is invisible and therefore crossable without warning. Explicitly marking the boundary — "I know retail banking well; commercial real estate I only know the surface of" — creates a cognitive speed bump before decisions in adjacent territory. The edge is where confidence is highest and accuracy is most likely to have diverged, making it the most dangerous point in the circle.
How to do it
- 1For a domain, ask: what are the adjacent areas where my knowledge starts to thin?
- 2Write a one-sentence description of where your knowledge ends for each major area of your work or life.
- 3When a decision touches an edge area, flag it explicitly before acting.
- 4Treat edge-area confidence as a warning sign, not a green light.
What the evidence says
ObservationalResearch on overconfidence shows it is highest in novel, adjacent domains — where the thinker knows enough to feel confident but not enough to know what they are missing. Experts in one field routinely overperform their actual knowledge when reasoning in adjacent fields.
Honest caveat: The specific mechanism of "edge overconfidence" is a principled extension of overconfidence research rather than an independently studied phenomenon.
Common mistake
Treating the edge as a gradient to push rather than a boundary to mark — continually rationalizing why the adjacent area is "close enough" to your core domain.
IX Coach helps you mark the edges of your confidence in a domain so you can be explicit about when a decision is inside vs. outside your circle.
Practice this with IX Coach →