Montesquieu's Spirit of the Laws: Comparative Politics and the Theory of Government

Montesquieu’s De l’esprit des lois (The Spirit of the Laws, 1748) is one of the foundational works of modern political science. The book is a comprehensive comparative study of laws, customs, and political institutions that established a new model of political analysis. This article examines the central arguments of The Spirit of the Laws, including its comparative method, its theory of government, and its lasting influence on the development of modern political science.

The Comparative Method

The most distinctive feature of The Spirit of the Laws is its use of 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 comparative method allowed Montesquieu to escape the limitations of the political philosophy of his predecessors. The range of his comparative materials is unprecedented in the European tradition: the English constitution, the Roman Republic, the Ottoman Empire, the Chinese Empire, the feudal kingdoms of medieval Europe, the absolutist monarchies of modern Europe, and the various forms of tribal and barbarian government were all examined in turn, and the strengths and weaknesses of each were identified with an empirical attention that was characteristic of the new science of politics.

The method also allowed Montesquieu to identify 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. Laws are not, in Montesquieu’s view, arbitrary impositions of the legislator; they are responses to the particular conditions of the societies in which they operate. The proper study of laws requires an understanding of these conditions.

The Theory of Government

Montesquieu develops a typology of governments that has been enormously influential. He distinguishes among three main kinds of government: republican, monarchical, and despotic.

Republican government is government in which the people as a whole, or a part of the people, have the sovereign power. Republican government can be either democratic (in which the people as a whole exercise the sovereign power) or aristocratic (in which a part of the people exercise it). The principle of republican government is virtue — the love of the public good and the willingness to subordinate private interests to the common good.

Monarchical government is government in which one person governs by fixed and established laws. The principle of monarchy is honor — the sense of personal dignity and the desire to deserve the respect of others.

Despotic government is government in which one person governs according to his own will and caprice, without law or restraint. The principle of despotism is fear — the terror that the ruler inspires in his subjects and that holds the system together.

Each kind of government, Montesquieu argues, is animated by a different principle, and the proper functioning of each requires the cultivation of its proper principle. The corruption of a government is the loss of its proper principle: a republic corrupted by the loss of virtue becomes a faction-ridden oligarchy; a monarchy corrupted by the loss of honor becomes a despotism; a despotism corrupted by the loss of fear becomes a tyranny.

The Theory of Separation of Powers

The most famous and most influential part of The Spirit of the Laws is the theory of the separation of powers, developed in Book XI. Drawing on his reading of the English constitution, Montesquieu distinguished among three kinds of political power: the legislative power, the executive power, and the judicial power.

Montesquieu argued that each of these powers should be exercised by a distinct body, and that the concentration of any two or more of them in the same person or body would be a threat to political liberty. “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 argument was grounded in a more general theory of political liberty. Montesquieu held that political liberty depended on the proper arrangement of the laws and institutions of a country, and that the proper arrangement was one in which no single person or group could exercise arbitrary power over the others.

The Theory 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, developed in Books XIV–XVII. 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 theory was developed in Books XIV–XVII, which contain extensive discussions of the influence of climate on the physical and psychological characteristics of different peoples. Montesquieu argued that the peoples of cold climates were generally more vigorous, more courageous, and more independent than the peoples of hot climates, and that the political institutions of the northern peoples were more likely to be republican or monarchical than the political institutions of the southern peoples.

The theory was controversial, and it was criticized for its determinism and for its implicit Eurocentrism. It was, however, an important contribution to the development of comparative sociology, and it helped to establish the modern understanding of the complex relationships between physical environment and social organization.

The Legacy

The Spirit of the Laws was enormously influential. The book was translated into every major European language, and it was read and discussed by everyone who was seriously interested in political theory. The American founders drew directly on Montesquieu’s arguments, and the French Enlightenment in general was deeply influenced by his comparative method and his political analysis.

Further Reading

• The Stanford Encyclopedia of Philosophy (plato.stanford.edu), relevant entry
• The Cambridge Companion to [Thinker] (Cambridge University Press)
• Isaiah Berlin, Four Essays on Liberty (1969)