What is belief perseverance?

Belief perseverance is a concept in personal epistemology: You unconsciously seek and emphasize evidence that confirms your existing beliefs.

Example: A senior engineer says 'the latency spike is definitely a database issue' and then spends forty minutes reading only database logs. The actual cause — a misconfigured load balancer — sits in plain view in the network dashboard they never opened. They weren't lazy or incompetent. Their belief selected which evidence counted as evidence.

This concept is part of Phase 5 (Observation Without Judgment) in the How to Think curriculum, which builds the epistemic infrastructure for observation without judgment.