What is separating facts from opinions?

Separating facts from opinions is a concept in personal epistemology: What you saw and what you concluded from it are distinct and must not be fused.

Example: Your coworker didn't respond to your Slack message for four hours. That's the observation. 'She's ignoring me because she's upset about the code review' is the interpretation. Write both down — separately. The observation is stable. The interpretation is a hypothesis you can test, revise, or discard.

This concept is part of Phase 2 (Atomicity and Decomposition) in the How to Think curriculum, which builds the epistemic infrastructure for atomicity and decomposition.