What is extended mind?

Extended mind is a concept in personal epistemology: When you trust your capture system your mind stops trying to hold everything.

Example: A software architect spends her Sunday mornings writing design documents — the kind of deep, architecturally consequential work that shapes entire systems. Before she built a trusted capture practice, those mornings looked different. She would sit down to write, and within minutes her mind would surface an unrelated concern: Did I reply to the vendor about the license renewal? What was the name of that paper on distributed consensus my colleague mentioned? I need to schedule the performance review for next week. Each thought felt urgent. Each pulled her out of the architectural thinking she was trying to do. She would open her email to check one thing, then spend forty minutes on a chain of small tasks that had nothing to do with system design. After eighteen months of building her capture system — a quick-capture shortcut on her phone, a physical notebook on her desk, a weekly review every Friday — those same thoughts still arise on Sunday morning. But now they land differently. 'Vendor license' goes into the capture tool in three seconds. 'Distributed consensus paper' gets a voice note. 'Performance review' is already in her system from Friday's review. Each thought is acknowledged, externalized, and released. She returns to architectural thinking without the mental residue. The thoughts did not stop coming. She stopped needing to hold them.

This concept is part of Phase 3 (Capture Systems) in the How to Think curriculum, which builds the epistemic infrastructure for capture systems.