Full Idea
To fairly divide a cake between two children, the first divides it and the second chooses. …Even division is best, as it anticipates the second child will take the largest piece. Fairness is enforced by the children's self-interests.
Gist of Idea
Self-interest can fairly divide a cake; first person cuts, second person chooses
Source
William Poundstone (Prisoner's Dilemma [1992], 03 'Cake')
Book Reference
Poundstone,William: 'Prisoner's Dilemma' [OUP 1992], p.43
A Reaction
[compressed] This is introduced as the basic principle of game theory. There is an online video of two cats sharing a dish of milk; each one drinks a bit, then pushes the dish to the other one. I'm sure two children could manage that.