It is said that children’s sense of fairness emerges at age 8 & is rooted in the aversion to unequal distributions; they add 2 twists: It emerges already at age 3 & only in the context of collaborative activities

Children’s Sense of Fairness as Equal Respect. Jan M. Engelmann, Michael Tomasello. Trends in Cognitive Sciences, Apr 2 2019. https://doi.org/10.1016/j.tics.2019.03.001

Highlights
If humans could survive and thrive entirely on their own, they would not concern themselves with dimensions such as equality, merit, and deservingness. Fairness is a form of cooperation as it enables individuals with conflicting interests to find mutually satisfactory solutions to the demands of interdependent lifeways.

Consistent with this evolutionary perspective, young children show a concern for fairness first inside, but not outside, of collaborative interactions with others in which they view their partners (but not free riders) as equally deserving participants.

In this context, children’s sense of fairness is not mainly about how material ‘stuff’ is distributed, but about the social meaning of the act of distribution. They thus are okay with an unequal distribution if the procedure was a fair one that gave everyone an equal chance. In general, children are concerned that acts of distribution treat everyone with equal respect.

One influential view holds that children’s sense of fairness emerges at age 8 and is rooted in the development of an aversion to unequal resource distributions. Here, we suggest two amendments to this view. First, we argue and present evidence that children’s sense of fairness emerges already at age 3 in (and only in) the context of collaborative activities. This is because, in our theoretical view, collaboration creates a sense of equal respect among partners. Second, we argue and present evidence that children’s judgments about what is fair are essentially judgments about the social meaning of the distributive act; for example, children accept unequal distributions if the procedure gave everyone an equal chance (so-called distributive justice). Children thus respond to unequal (and other) distributions not based on material concerns, but rather based on interpersonal concerns: they want equal respect.