The Spirit of the Laws

Overview

The Spirit of the Laws is seven hundred and fifty pages in thirty-one books, published anonymously in Geneva in 1748 after roughly twenty years of work. Montesquieu was a Bordeaux magistrate who had inherited a presidency in the parlement, sold the office, travelled Europe for three years, and spent the rest of his life reading and writing this. The Catholic Church put it on the Index of Prohibited Books in 1751 and he wrote a defence of it that did not help.

The structure is not what a modern reader expects. Books are short, chapters are sometimes a paragraph, and the subjects jump: from the principles of government to the education of children to criminal procedure to climate to commerce to the origin of feudal law in France, which occupies the last six books and which almost nobody reads. Montesquieu said he had followed his object without any fixed design, and the book reads like it.

His method is what makes it new. He announces at the start that he has not drawn his principles from his prejudices but from the nature of things, and that he is looking for the relations laws have to the climate, religion, commerce, manners and history of the people who have them. That word relations is the key: laws are not to be assessed against an ideal but explained by their circumstances.

The argument

Books I to VIII: the three governments. Montesquieu classifies by a scheme he invented. Each form has a nature, which is its structure, and a principle, which is the human passion that makes it work.

A republic is government by the people or part of them, and its principle is virtue, by which he means a political virtue, love of the laws and of equality and a willingness to prefer the public interest to one’s own. Republics therefore have to be small and austere; commerce and luxury corrode them.

A monarchy is rule by one according to fixed and established laws, and its principle is honour, the desire for rank and distinction. Montesquieu’s point, which is subtler than it looks, is that a monarchy does not need its subjects to be virtuous, because ambition and vanity produce the same results, and this is why monarchies are more durable than republics and can bear commerce and inequality.

Despotism is rule by one according to no law at all, and its principle is fear. Montesquieu’s descriptions of it are the most vivid writing in the book, and his readers understood that the ostensible subject, the Ottoman and Persian courts, was a way of talking about France.

When the principle is corrupted the form dies. A republic whose citizens stop loving equality becomes something else regardless of what its constitution says.

Books XI and XII: liberty and the separation of powers. The part that mattered historically.

Montesquieu first clears away the loose usages of the word liberty and defines it as the right to do what the laws permit, and as the tranquillity of mind that arises from the opinion each person has of his own safety.

Then the mechanism. Everyone with power is apt to abuse it and to push it as far as it will go; this is not a judgement about character but an observation about the nature of things; therefore power must be arrested by power. He identifies three powers, legislative, executive and judicial, and argues that liberty is lost whenever two of them are held by the same body: if legislative and executive are united, the same men may pass tyrannical laws and execute them tyrannically; if judicial is joined to legislative, the judge is the legislator and can do anything; if to executive, the judge has the force of an oppressor.

He presents England as the constitution where this has been achieved. It had not, in the form he describes; the English executive sat in the legislature and depended on it. The misreading became a blueprint, and Madison built on it in Federalist 47 and 51 while modifying it, arguing that pure separation is impossible and that what is needed is partial separation with each branch given constitutional means to resist the others.

Books XIV to XVIII: climate and terrain. The theory that laws should be adapted to the physical circumstances of a people, and beyond that that climate shapes temperament directly. Cold air contracts the fibres and increases vigour; heat relaxes them and produces languor and sensuality. From this Montesquieu derives differences in courage, in sexual custom, in receptiveness to despotism, and in the laws each climate requires.

This is the weakest part of the book and it was the most influential in its own century. It is also worth noticing what he does with it: the argument is comparative and naturalistic, treating law as an effect of conditions rather than of national character in a mystical sense, and that move survived even though the physiology did not.

Book XV: slavery. The chapters on slavery are the most famous short passage. Montesquieu argues that it is contrary to nature, useless, and dangerous to the master, and then writes a chapter setting out the arguments in its favour one after another in a completely flat voice: that sugar would be too expensive otherwise, that the people in question are black from head to foot and have such flat noses that it is impossible to pity them, that it is impossible to suppose such creatures to be men because if we supposed them men we should begin to believe we were not Christians. The irony is unmistakable and it was read as irony at the time. He also, in the climate books, allows arguments that slavery may be less unreasonable in very hot countries, which has troubled every subsequent reader.

Books XX to XXIII: commerce and population. Trade softens manners and inclines nations to peace, because two nations that trade become mutually dependent. This is the doux commerce thesis and it runs through Hume and Smith into modern liberal theory.

Books XXIV to XXXI: religion and French feudal law. The last section, on the history of French institutions, is antiquarian and is where most readers stop.

How to read it

Read Books I to VIII for the typology and Books XI and XII for the separation of powers. That is the argument and it is perhaps a hundred and fifty pages.

Then read Book XV on slavery, and Book XX on commerce, and stop unless you have a particular interest.

Use the Cambridge translation by Cohler, Miller and Stone, which is accurate and has the apparatus. Nugent’s eighteenth-century version is free and is what the American founders actually read, which is a reason to look at it.

Read Book XI chapter 6 next to Federalist 47 and 51. Madison quotes Montesquieu, calls him the oracle who is always consulted on this subject, and then explains why the pure doctrine will not work and what to substitute. The pair shows a theory being turned into a machine.

Take the climate chapters as a case study rather than skipping them. They are wrong, they were taken seriously by serious people, and they show what happens when a naturalistic method is applied without any way of testing its causal claims.

And notice the method throughout. Montesquieu asks why a people has the laws it has rather than what laws it ought to have, and the shift is what makes him the first modern political scientist rather than the last of the natural law theorists.

Questions it raises

• Power must check power. Is that a claim about human nature, about institutions, or a rule of thumb that happens to work?
• Each government has a principle it dies without. Does that describe anything real, or is it a scheme imposed on the evidence?
• Montesquieu described an England that did not exist and the description changed the world. What does that say about the relation between political theory and political fact?
• Liberty is the right to do what the laws permit. Does that definition protect anyone against bad laws?
• The climate theory is comparative, naturalistic and false. Which parts of his method survive its failure?
• The chapter on slavery is sustained irony in a book that elsewhere half-excuses it. How should a reader hold those two passages together?