Montesquieu
French Enlightenment political philosopher, jurist and writer (1689–1755), born at the Château de La Brède near Bordeaux, president of the Parlement of Bordeaux and member of the French Academy, whose practical legal training instilled in his work a sociological realism rare among the political philosophers of his time. His first major work, the Persian Letters (1721), published anonymously as a precaution, is a brilliant satire of French society seen through the estranged eyes of two imaginary Persian travellers, one of the earliest examples of using an 'exotic' gaze as a strategy of social criticism. His magnum opus, The Spirit of the Laws (1748), the fruit of twenty years of comparative research into the laws, customs, climates and institutions of dozens of historical and contemporary societies, founded what we would today call comparative political sociology: it argues that a society's laws should not be judged abstractly but in relation to its 'spirit' — that is, the totality of physical factors (climate, geography) and moral factors (religion, customs, commerce) that shape it. His most influential and lasting contribution is the theory of the separation of powers — legislative, executive and judicial — which he developed while particularly admiring the English constitutional system, and according to which political liberty is only possible when these powers mutually limit one another, preventing any one of them from becoming absolute: 'so that power cannot be abused, it is necessary that, from the very arrangement of things, power checks power'. This doctrine exerted a direct and decisive influence on the framers of the United States Constitution and on virtually every subsequent liberal constitution, making Montesquieu one of the most direct intellectual architects of modern constitutionalism.