What is taxonomy design?

Taxonomy design is a concept in personal epistemology: Nested categories with parent-child relationships create powerful organizational structures.

Example: You have 200 notes tagged by topic. Some tags are broad ('psychology'), some narrow ('cognitive load theory'). Without hierarchy, all 200 tags sit at the same level and you scroll through an undifferentiated list every time you need to find something. The moment you nest 'cognitive load theory' under 'psychology' under 'behavioral science,' you can navigate from the general to the specific in three clicks — and you can see, at a glance, that psychology contains twelve sub-topics while ethics contains three. The hierarchy makes relative density visible.

This concept is part of Phase 12 (Classification and Typing) in the How to Think curriculum, which builds the epistemic infrastructure for classification and typing.