Assume Good Faith
Assuming good faith means assuming that people are not deliberately trying to cause harm [1].
Hanlon's Razor
"Never attribute to malice that which is adequately explained by stupidity."
— Robert J. Hanlon, Hanlon's Razor [2]
Retrospective Prime Directive
"Regardless of what we discover, we understand and truly believe that everyone did the best job they could, given what they knew at the time, their skills and abilities, the resources available, and the situation at hand."
— Norm Kerth, Project Retrospectives: A Handbook for Team Review [3]