Why psychological safety isn't about being nice
Psychological safety is often translated into practice as "be nice" — soften feedback, avoid conflict, keep the mood pleasant. That's a misreading of the research it comes from.
Teams with high psychological safety don't have less conflict. They have more of it, out loud, where it can be resolved. What they have less of is the private kind: the quiet workaround, the withheld concern, the bug report that never gets filed because raising it once went badly.
Safety is what makes disagreement cheap enough to have in the open instead of expensive enough to avoid. A manager building it isn't lowering the temperature of every conversation — they're making sure the cost of speaking up is lower than the cost of staying quiet, especially when someone is about to be proven wrong in front of the group.