Montesquieu

Montesquieu was a French Enlightenment political philosopher best known for his theory of the separation of powers, which became a cornerstone of modern constitutional government. His work The Spirit of the Laws systematically compared political structures across cultures.

Montesquieu's comparative method in political philosophy — analysing how geography, climate, and culture shape legal systems — was a major influence on the framers of the American Constitution. His typology of republican, monarchical, and despotic governments remains a touchstone of political theory.