The evidence here is thinner than the confident commentary suggests, and the honest position is a shrug with a direction of travel. The measure that matters is not what people say about kindness but what they do when nobody is scoring. The mind that evolved for small groups and immediate dangers is now asked to manage a pension. It does its best. We describe the departure from the model as an error. We might equally describe the model as a hopeful guess about us.
Where the model breaks
What looks like kindness from the outside is usually something simpler from the inside: tiredness, a deadline, a wish not to look foolish. Put a number on kindness and it becomes a target; put a target on it and the number stops meaning what it meant. In the studies we have, the effect is modest, reliable and almost entirely ignored by the people it describes. Consider a good excuse. It is a small thing, and small things are where habits live.
