Abstract
The origin of justice and its evolutionary functions are theoretically reconstructed. The origin of social norms/law and their evolutionary functions are also theoretically reconstructed. The relationship between justice and social norms/law is critically analyzed. The selection pressure in human evolution of 2 million years of the Pleistocene gave our ancestors the evolutionary advantage of acquiring the notion of justice and social norms/law and of behaving, feeling, and evaluating accordingly. The kin selection, reciprocal altruism, and intergroup selection all worked for human to behave, feel, and evaluate like human in order to enhance his/her evolutionary fitness. Since the evolutionary process is stochastic and recursive, and since the population genetics is a statistical dynamics, the distributions of various conceptions of justice, social norms, and law on the human population do not and cannot converge even in equilibrium. In the case of law, the results of social choice theory and public choice theory suggest that legislative process introduces additional complexity to law. The evolutionary perspective sheds new lights on the relationship among law, social norms, and justice.
