What is ACT therapy defusion?

ACT therapy defusion is a concept in personal epistemology: Thoughts are not you — they are objects you can craft, version, and reuse across contexts.

Example: You think 'we should rewrite this system in Rust' on Monday and 'we should keep the Python stack' on Thursday. Both thoughts came from you. Neither one is you. Write them both down. Now you have two competing objects you can weigh, combine, or version — instead of an identity crisis about what kind of engineer you are.

This concept is part of Phase 1 (Perception and Externalization) in the How to Think curriculum, which builds the epistemic infrastructure for perception and externalization.