What is extreme cases?

Extreme cases is a concept in personal epistemology: Unusual or extreme situations reveal where your schema breaks down.

Example: You believe 'hard work leads to success' — a schema that's worked for twenty years. Then you watch someone work brutally hard and fail because the market shifted, or someone succeed with minimal effort because they were in the right network. These aren't exceptions to dismiss. They're edge cases that reveal the boundaries your schema can't account for: luck, timing, structural privilege, domain mismatch. The schema isn't wrong — it's incomplete. The edge cases tell you exactly where.

This concept is part of Phase 15 (Schema Validation) in the How to Think curriculum, which builds the epistemic infrastructure for schema validation.