It is tempting to call this irrational. It is more useful to ask what it is for. A better account of kindness would begin with the ordinary case rather than the laboratory one. The evidence here is thinner than the confident commentary suggests, and the honest position is a shrug with a direction of travel. If you want to see kindness at work, watch a queue form where there is no reason for one.
Why it persists
The point is not that people are foolish. The point is that kindness is expensive, and we economise on it like everything else. In the studies we have, the effect is modest, reliable and almost entirely ignored by the people it describes. A better account of kindness would begin with the ordinary case rather than the laboratory one. None of this is new. Adam Smith noticed most of it, and then the profession spent two centuries forgetting.
