Young children judge defection less negatively when there's a good justification

Morality includes a common ground ranking of values, of which a central theme is that prosocial actions are more justifiable than selfish ones. Learning to distinguish between good versus bad justifications for actions based on a common ground ranking of values is a key aspect of moral development. The current study assessed this type of understanding in young children. In a within-participants design, young children (N = 64) saw puppets who promised to show them a cool toy, failed to fulfill their promise, and then gave either a good (prosocial), bad (selfish), or no justification for their defection. Children's judgments about defection following good justifica-tions were less negative than their judgments about defection following bad or no justifications, which did not differ. When asked to justify their judgments, 5-year-olds (but not 3-year-olds) made more normative or promise-referencing statements when reasoning about puppets who gave good justifications as opposed to bad or no justifications. Children's rates of tattling on, liking, and inviting puppets to play did not vary by the type of justification that a puppet gave. Overall, the findings suggest that the capacity to reference a common ground ranking of values, a key component of human cooperation and morality, is present in young children.