What is expertise boundaries?

Expertise boundaries is a concept in personal epistemology: Being well-calibrated in one area does not transfer automatically to others.

Example: A senior engineer who accurately estimates software project timelines within two weeks consistently gets blindsided by home renovation budgets, investment returns, and how long it takes to learn a new language. Her calibration — hard-won through thousands of shipping cycles — lives inside the domain where she built it. Outside that domain, she's as overconfident as anyone else.

This concept is part of Phase 8 (Perceptual Calibration) in the How to Think curriculum, which builds the epistemic infrastructure for perceptual calibration.