CONCEPT
The Practitioner's Repertoire
Schon's name for the accumulated, experientially indexed body of examples, patterns, and moves that organizes professional perception — built through practice, indexed by significance, and irreducible to any external representation.
The practitioner's repertoire is what makes reflection-in-action possible. It is not a database of facts or a collection of rules. It is an organized, experientially indexed, emotionally weighted body of knowledge that shapes perception itself — that determines what the practitioner sees, hears, feels, and notices in the first place. The diagnostician reading a chest X-ray in eleven seconds, the master chef tasting a sauce and identifying what it needs, the experienced developer sensing that an architecture will not scale — all draw on repertoires built through thousands of prior encounters whose lessons cannot be reduced to propositions. Schon argued that the repertoire, not formal knowledge, is what makes the competent practitioner competent. The AI moment tests this claim by creating a tool whose computational repertoire is vast, wide, and structurally different in kind from the practitioner's own.
In The You On AI Field Guide
The repertoire has properties that matter enormously in the context of AI. First, it is built through friction