What is tight coupling systems?

Tight coupling systems is a concept in personal epistemology: Small uncorrected errors can trigger chains of increasingly large errors.

Example: You misread a quarterly revenue figure by one decimal place in a spreadsheet. You build a forecast on that number. Your team allocates budget based on the forecast. A hiring plan follows the budget. Three months later, the company has eight new employees it cannot afford — not because anyone made a reckless decision, but because a single transcription error propagated through four layers of dependent decisions without anyone checking the upstream data. Each decision was locally rational. The cascade was already in motion before anyone suspected a problem.

This concept is part of Phase 25 (Error Correction) in the How to Think curriculum, which builds the epistemic infrastructure for error correction.