The British Academy Lecture, delivered by Dr Mogens Hansen FBA, on 25 February 2010 (venue: The British Academy).
The theory of the separation of powers between a legislature, an executive and a judiciary is the foundation of modern representative democracy. It was developed by Montesquieu and came to replace the older theory of the mixed constitution which goes back to Plato, Aristotle and Polybios, that there are three types of constitution: monarchy, oligarchy and democracy. When institutions from each of the three types are mixed, an interplay between the institutions emerges that affects all functions of state. Today Montesquieu's separation of powers is obsolete. The mixed constitution deserves to be revived as a corrective to the prevailing view that western states are pure democracies. Ancient political thought is remarkably modern or – rather – modern political thought has much to learn from the Greek and Roman political thinkers.
About the speaker
Mogens Herman Hansen, a Corresponding Fellow of the British Academy, is Reader in Classics at the Saxo Institute, Copenhagen University. He was director of the Copenhagen Polis Centre (1993–2005) and is the author of books and articles on Athenian democracy, the ancient Greek citystate (polis) and the demography of the ancient Greek world.
(The text of this lecture was published as 'The mixed constitution versus the separation of powers: Monarchical and aristocratic aspects of modern democracy' by Mogens Hansen, in History of Political Thought, 31:3 (Autumn 2010), 509-531.)