ABSTRACT
This chapter looks at the way in which Thomas Aquinas understood the relationship between the various forms of human community. It focuses on the Aquinas's theory of law and politics and thus with the specifically 'political' categories of city, province and empire, together with the associated concepts of kingdom and nation. Aquinas's treatment of city, province and empire – in other words, his treatment of issues relating the problem of subsidiarity and federalism – was foundational to and culminated in his account of the best constitution. The chapter shows how Aquinas's went about adapting Aristotelian political philosophy to the theological beliefs and institutional conditions of his own time. It turns to Aquinas's theory of the best constitution, and offers an interpretation that seeks to integrate his discussion of the mixed regime with his account of societal, ecclesiastical and political pluralism.
