What does it mean that multiple perspectives reveal blind spots?

Seeking other viewpoints shows you what your single perspective cannot.

Example: You design an API and think it's clean. A frontend engineer points out the response shape forces three extra transformations. A security engineer flags an unvalidated parameter you never considered. A customer support lead notes the error messages are meaningless to end users. None of these people are smarter than you — they are differently positioned. Each perspective reveals structure you literally could not see from where you stand.

Try this: Pick a decision you've recently made or a design you've recently shipped. Write down your perspective in two sentences. Then ask three people with different roles, experiences, or stakes to describe what they see. Write each perspective on a separate card. Compare them side by side and mark anything that appears in their observations but not in yours — these are your blind spots on this specific problem.