In what follows we digress from the last chapter to sketch Kant's train of thought leading to the three institutions (iustitia tutatrix, iustitia commutativa, and iustitia distributiva). This digression should also make Kant's terminology more transparent. We show that Kant originally distinguished only between commutative justice and distributive justice, and did not discuss the idea of protective justice as embodied in the iustitia tutatrix at all. As noted in Chapter 1, Kant does not use the Scholastic understanding of commutative and distributive justice. For the Scholastics, commutative and distributive justice were virtues. For Kant, in contrast, they are institutions. We explain the radical change between the Scholastic and Kant's views of these two types of justice, tracing this change to Hobbes. Indeed, Hobbes not only provides the frame of reference for Kant's definitions of commutative and distributive justice, but also formulates an early version of what for Kant later becomes the postulate of public law with its dictate to move to a juridical state. Kant refines Hobbes' concepts and ultimately adopts a third – protective justice – by the time he writes the Doctrine of Right.

KANT'S DEVELOPMENT OF HOBBES' DISTINCTION BETWEEN COMMUTATIVE AND DISTRIBUTIVE JUSTICE

We find the background for Kant's ideas on public justice in Hobbes' thoughts on the concepts iustitia commutativa and iustitia distributiva. In Leviathan, as in De Cive, Hobbes rejects the Aristotelian-Scholastic tradition and with it the Scholastic definitions of commutative and distributive justice.