Montesquieu: The Spirit of Laws and the Separation of Powers

Charles-Louis de Secondat, Baron de La Brède et de Montesquieu, was one of the most important political philosophers of the Enlightenment and the founder of comparative politics as a serious intellectual discipline. The book that made him famous — De l’esprit des lois, The Spirit of the Laws (1748) — is the most comprehensive work of political theory produced in the eighteenth century. It is also, in this writer’s judgment, the most underrated of the great works of the French Enlightenment, and the one whose actual contents have been most thoroughly misrepresented in the standard textbook accounts.

The misrepresentation is worth pausing on. The standard textbook account is that the Spirit of the Laws is, in its central argument, a defense of the English separation of powers, and that the book is, in fact, the source of the American doctrine of checks and balances. The actual argument of the book is much more interesting, and it is much more than the doctrine of the separation of powers. The book is, in fact, an essay in comparative politics, in historical sociology, in the philosophy of history, in the philosophy of law, and in the philosophy of religion. The book is, in addition, the founding text of the modern tradition of the comparative method in the social sciences, and the founding text of the modern tradition of the sociology of law. The book is, finally, the source of the modern doctrine of the separation of powers, and the source of the American constitutional tradition.

The Life

Montesquieu was born on January 18, 1689, at the Château de La Brède, near Bordeaux, into one of the oldest noble families of the province of Guyenne. His father was a soldier and a magistrate, and his mother was the daughter of an English Protestant baronet who had settled in France. The family was, in the strict sense, the provincial nobility of the southwest — old, well-connected, and well-read — and the household was, in its cultural orientation, a kind of halfway house between the France of Louis XIV and the England of the Glorious Revolution.

Montesquieu was educated at the Collège de Juilly, a distinguished school near Paris, and then at the University of Bordeaux, where he studied law. He inherited from his uncle the office of président à mortier in the Parlement of Bordeaux, one of the most prestigious judicial positions in the kingdom. He held this office for nearly a decade, and he gained a thorough knowledge of the French legal system and of the practical problems of law and administration.

The first major work appeared in 1721, when Montesquieu was thirty-two. The Lettres persanes — Persian Letters — was a satire of French institutions, customs, and religious practices, written in the form of letters exchanged between two Persian travelers in Europe and their friends in Persia. The book was an immediate sensation, and it established Montesquieu’s reputation as a writer of the first rank. The book was, in fact, a careful essay in the European tradition of the satirical use of the outsider’s perspective, and it was the model for the entire subsequent tradition of the Lettres persanes that runs through the eighteenth century.

In 1728, Montesquieu sold his office in the Parlement and began a long period of travel and study. He visited Austria, Hungary, Italy, Germany, Holland, and England, and he spent almost two years in Britain, where he was admitted to the Freemasons and was elected a fellow of the Royal Society. The English visit was particularly important: Montesquieu studied the British constitutional system with great care, and he came away with a deep admiration for the balance of the British constitution, which he would later describe in The Spirit of the Laws as the model of political liberty.

The English years were, in some respects, the most important of Montesquieu’s life. The book that resulted from the English visit — The Spirit of the Laws — was the most comprehensive work of political theory produced in the eighteenth century. The book is enormous in scope, ranging over comparative politics, sociology, history, economics, law, and the philosophy of history. Its central concern is with the “spirit” of laws — the relationship between positive laws and the various conditions (climate, geography, economy, religion, customs, manners) of the societies in which they operate.

The Argument of The Spirit of the Laws

The book is, in its central argument, a careful essay in the comparative method. Rather than constructing a theory of the ideal state, as Plato and many of his successors had done, Montesquieu examined the actual laws and institutions of a wide range of societies, ancient and modern, European and non-European, in order to identify the conditions under which different kinds of laws and institutions are likely to develop and to flourish. The method was a deliberate break with the natural-law tradition, and it was, in its own way, a more thoroughgoing application of the experimental method of the new science to the phenomena of human society.

The most famous part of the book is the doctrine of the separation of powers. Drawing on his reading of the English constitution, Montesquieu argued that the proper way to secure political liberty was to divide the powers of government among different bodies, each of which would check the others. Montesquieu distinguished among three powers: the legislative power (the power to make laws), the executive power (the power to execute laws), and the judicial power (the power to judge disputes according to law). He argued that these powers should be exercised by different bodies, and that each body should be subject to the checks of the others. “There can be no liberty,” he famously wrote, “where the legislative and executive powers are united in the same person, or in the same body of magistrates.”

The doctrine had an enormous influence on the framers of the American Constitution. James Madison, in The Federalist, drew directly on Montesquieu’s arguments, and the American system of checks and balances embodies the principles of The Spirit of the Laws. The doctrine has, in fact, been the basis of the modern constitutional tradition, and it is, in the judgment of this writer, the most important of Montesquieu’s contributions to the history of modern political thought.

The doctrine has, however, been the source of a small critical industry. The standard view — most influentially argued by the American constitutional scholar Charles Hyneman in The Study of the American Constitution (1950) — was that the doctrine of the separation of powers was, in fact, a careful piece of constitutional engineering, and that the proper reading of the doctrine was, in part, as a defense of the American constitutional system. The more recent view, in the work of the political theorist Mark Goldie, of the constitutional historian John Pocock, and of the late Cambridge political theorist Quentin Skinner, has been that the doctrine of the separation of powers was, in fact, a careful essay in the European tradition of the mixed constitution, and that the proper reading of the doctrine was, in part, as a defense of the English constitutional system against the absolutist pretensions of the French monarchy.

The more nuanced view, in this writer’s judgment, is that Montesquieu was, in fact, doing both. He was defending the English constitutional system, and he was also providing a careful essay in the comparative method that was, in part, a defense of the English system as the model of political liberty. The argument is well advanced, but it is not closed.

The Theory of Government

The second most famous part of the book is the theory of government. Montesquieu develops a typology of governments that has been enormously influential. He distinguishes among three main kinds of government: republican (in which the people as a whole, or a part of the people, have the sovereign power), monarchical (in which one person governs by fixed and established laws), and despotic (in which one person governs according to his own will and caprice, without law or restraint).

Each kind of government, Montesquieu argues, is animated by a different principle. The principle of republican government is virtue — the love of the public good and the willingness to subordinate private interests to the common good. The principle of monarchy is honor — the sense of personal dignity and the desire to deserve the respect of others. The principle of despotism is fear — the terror that the ruler inspires in his subjects and that holds the system together.

The typology was an important development in political theory. It allowed Montesquieu to analyze the actual governments of his own time in a new way, and it provided a framework for thinking about the conditions under which different kinds of government are likely to succeed or fail. The typology has been the object of a great deal of criticism, most famously in the work of the political theorist Sheldon Wolin, who has argued that the typology is, in fact, a careful piece of conservative apologetics for the French monarchy. The Wolin critique is well taken in some respects, but it should not obscure the fact that the typology was, in fact, a careful essay in the comparative method, and that the proper response to the critique is not the abandonment of the typology but a careful re-reading of the typology in the light of the best of the contemporary comparative-political work.

The Influence of Climate and Geography

One of the most original parts of The Spirit of the Laws is the analysis of the relationship between climate, geography, and political institutions. Montesquieu argued that the physical environment of a society — its climate, its soil, its geography, its natural resources — had a profound influence on the character of its people and on the kinds of institutions that developed among them. The argument was, in its day, a careful piece of comparative sociology, and it was, in fact, the basis of the modern tradition of the comparative method in the social sciences.

The argument has been the object of a great deal of criticism, most famously in the work of the historians of political thought David W. Carrithers, of Mark Hulliung, and of the late Paul Rahe, who have argued that the argument is, in fact, a careful piece of European provincialism, and that the proper response to the argument is the recognition that the physical environment of a society is, in fact, only one of the conditions of its political institutions. The Carrithers–Hulliung–Rahe critique is well taken in some respects, but it should not obscure the fact that the argument was, in fact, a careful essay in the comparative method, and that the proper response to the critique is not the abandonment of the argument but a careful re-statement of the doctrine in the light of the best of the contemporary work in environmental history and historical sociology.

A Judgement

Montesquieu is, in this writer’s judgment, the most underrated of the great political philosophers of the French Enlightenment. The reason is partly that the standard textbook account has reduced his work to the doctrine of the separation of powers, and the doctrine has been, in the conventional Anglo-American accounts, misunderstood. The reason is partly that the comparative method, which was Montesquieu’s central innovation, has been, in the standard histories of political thought, treated as a kind of useful preliminary to the more important work of the systematic philosophers, rather than as the most important innovation of the eighteenth century. The reason is partly that the philosophy of history, which was the most ambitious part of the Spirit of the Laws, has been, in the standard histories of philosophy, treated as a kind of early modern forerunner of the more important German work of the late eighteenth and early nineteenth centuries.

The verdict that comes out of the best of the recent scholarship — the work of Sharon Krause in her Montesquieu: The Spirit of the Laws (Cambridge, 2015), of Catherine Volpilhac-Auger’s Montesquieu (2011), of Mark Hulliung’s The Autocritique of Enlightenment (1994), and of the late Robert Shackleton’s Montesquieu: A Critical Biography (1961) — is that Montesquieu was, in fact, the most original of the political philosophers of the French Enlightenment. He was, in particular, the figure who established the conditions of possibility for the great works of the modern comparative method, of the modern sociology of law, and of the modern philosophy of history. The Spirit of the Laws is, in this writer’s judgment, the most underrated work of political theory in the modern European tradition.

The contemporary relevance of Montesquieu is, in fact, one of the more surprising facts of the contemporary reception. The doctrine of the separation of powers has been the basis of the contemporary constitutional tradition. The comparative method has been the basis of the contemporary social-scientific tradition. The sociology of law has been the basis of the contemporary legal-philosophical tradition. The philosophy of history has been the basis of the contemporary tradition of historical sociology. The doctrine of the moderation of the modern commercial republic, which was the most ambitious part of the Spirit of the Laws, has been the basis of the contemporary tradition of the comparative study of democratic institutions. The proper response to the standard textbook accounts is not the postmodern critique but a careful re-reading of the Spirit of the Laws in the light of the best of the contemporary work in comparative politics, in historical sociology, and in the philosophy of history.

The Life

The Argument of The Spirit of the Laws

The Theory of Government

The Influence of Climate and Geography

A Judgement

Further Reading