Considerations on the Causes of the Greatness of the Romans

Quick Facts

• Full title: Considerations on the Causes of the Greatness of the Romans and Their Decline
• Author: Montesquieu
• First published: 1734, anonymously
• Form: Short historical and political study of Rome
• Main question: Why did Rome become so powerful, and why did that same power help ruin it?
• Main themes: republic, civic virtue, empire, corruption, military expansion, institutions, historical causation

The Problem

Montesquieu is asking why political orders grow, decay, and die. Rome is his test case because it went from a small city to a world empire and then lost the political energy that had made it strong.

He does not treat Roman history as a string of accidents or as the story of a few heroic leaders. A cause here means a condition that pushes events in a direction. A good general or a lucky battle matters, but Montesquieu thinks those events usually work inside deeper causes: laws, habits, military organization, religion, wealth, class conflict, and the size of the state. Rome becomes a way to ask whether a republic can survive its own success.

In One Minute

Considerations argues that Rome became great because its institutions and civic habits were built for public discipline and war. Early Rome had citizens who prized the common good, leaders who gained honor through service, a senate skilled in long policy, and armies trained by constant conflict.

But conquest changed Rome. Wealth from empire produced inequality and luxury. Armies serving far from home became attached to their generals instead of the republic. Commanders such as Sulla, Pompey, and Caesar could use military glory as a private political weapon. The city kept republican names for a while, but real power moved toward personal rule.

The central lesson is sharp: the same forces that made Rome strong also made it unstable. A small warlike republic could conquer an empire, but it could not easily remain free while ruling one.

The Main Argument

Montesquieu begins with the Roman Republic because that is where he sees the source of Roman power. A republic is a political order in which public life depends on citizens taking part in rule and accepting limits for the whole community. In Rome, this meant a mixed system of magistrates, senate, popular assemblies, family discipline, military service, and public religion.

The early Romans, as Montesquieu describes them, had civic virtue. Civic virtue means willingness to put the city before private comfort. A Roman farmer-soldier who leaves his field to fight and accepts harsh discipline is the kind of example he has in mind. Virtue is public toughness: courage, frugality, obedience to law, and hatred of rule by one man.

Rome’s institutions rewarded that spirit. Consuls held office briefly, so they sought honor through visible service. The senate gave continuity to policy. The censorship watched morals and public rank. Military discipline turned citizens into soldiers.

Expansion changed the scale of politics. A city republic could be held together by reputation, shared hardship, and fear of nearby enemies. An empire brought provinces, money, slaves, long commands, and private fortunes. The old habits no longer fit the new size.

This is Montesquieu’s main move. He does not say Rome declined only because Romans became morally weak. He says success created new incentives. A victorious general controlled troops, money, and fame. Soldiers who depended on him for rewards became his clients. The republic was not designed to absorb that much power.

The empire that followed solved some problems by concentrating authority, but it created others. Personal rule made politics depend on emperors, court factions, military loyalty, taxes, and succession struggles. Decline is not one event. It is the slow loss of the habits and institutions that once made Roman power possible.

Key Ideas With Examples

• General causes: Broad forces that shape events more than single accidents do. Example: Caesar mattered, but Montesquieu thinks Caesar became possible because Roman conquest had already made generals too powerful.

• Civic virtue: Public-minded discipline in a republic. Example: a citizen who values Rome’s survival more than wealth, ease, or personal rule shows civic virtue.

• Corruption: The breakdown of the motives a political order needs to survive. In Rome, citizens and soldiers stop caring first about the republic and start caring more about luxury, patronage, faction, and private command.

• Empire: Rule over many peoples and territories from a central power. For Montesquieu, empire changes incentives: provinces create wealth, long wars create famous generals, and distant armies become hard for republican institutions to control.

• Institutions: Durable offices, laws, and customs that channel ambition. The senate, consulship, censorship, assemblies, and army did not remove ambition. They gave it public forms. When empire outgrew those forms, ambition became dangerous.

• Historical causation: Explaining history by asking what conditions made events likely. Montesquieu asks why free states can lose liberty after victories, and why military glory can turn into personal power.

Why It Matters

The book is an important step in Montesquieu’s political thought. It points toward the method of The Spirit of the Laws: explain laws and governments by looking at their setting, including size, economy, religion, military organization, customs, and balance of powers.

It also gives a classic warning about republican empire. A republic may need virtue, equality, and active citizens. Empire tends to bring wealth, hierarchy, distance, professional armies, and dependence on commanders. That tension shaped later debates about constitutional design.

The book also matters for history-writing. Montesquieu treats Rome as a political organism with causes of growth and decay. That helped shape later Enlightenment histories of why Rome fell.

Proponents, Critics, and Opponents

Machiavelli is the closest earlier comparison. Like Machiavelli in the Discourses on Livy, Montesquieu reads Roman history as a school of political judgment. Both take conflict, military organization, and republican energy seriously.

Later Enlightenment readers used the book as a model for explaining political change through causes rather than providence. Edward Gibbon’s Decline and Fall of the Roman Empire took up a larger version of the same question.

Critics push back in several ways. Christian readers could object to Montesquieu’s treatment of religion as one political cause among others, especially in the later empire. Modern historians also treat Rome’s “decline” more carefully than Montesquieu did. Many now stress transformation, regional variation, economic pressure, border politics, civil war, disease, and administrative change rather than a single moral decay story.

The strongest use of the book is not as a final explanation of Rome. It is as a political lesson about scale: institutions that work in one kind of society can fail when success changes the society they were built to govern.

Related Pages

• Montesquieu
• The Spirit of the Laws
• Machiavelli
• Roman Republicanism
• Roman Law
• Political Liberalism