Abstract
In numerous places in his Ethics and Politics, Aristotle associates political justice (or ruling in turns) and the regime of polity. I argue that there is a necessary connection between political justice and polity due to their origins in political mixing. Aristotle is the first to discover political justice and polity because his predecessors had thought that the elements which they combine -- excellence and equality in the case of political justice, and oligarchy and democracy in the case of polity -- were antithetical. The novelty of Aristotle's 'discoveries' points to their connection, namely that both originate in the political mixing of elements. This article examines such political mixing in detail and shows how an institutional arrangement such as ruling in turns can be adapted to different regime-types