Polybius and the Separation of Powers

by Paul Meany

Any American high schooler can tell you that the separation of powers is one of the defining features of the American government. The division of political power into the legislative, executive and judicial branches is a well-known practice in many Western countries. But where did this idea originate? This idea did not derive wholly from Enlightenment or modern thinkers. On the contrary, the division of powers was first proposed by Polybius, a Greek thinker of the second century BC.

Polybius was born around 208 BC in Arcadia, a region located in Greece’s Peloponnese. His father, Lycortas, was a politician and loyal ally to the Achaean league, a federalist organization among Greek city-states that aimed to preserve local independence through collective action. Following in his father’s footsteps, Polybius became a statesman and cavalry commander in the Achaean league. The focus of his political career was the preservation of the league’s independence through cooperation with the powerful Roman hegemony.

The Achaean league was initially aligned with Rome in opposition to the kingdom of Macedonia. When the league began to contemplate the idea of an alliance with Macedonia, the Romans reacted quickly by seizing a swathe of hostages to ensure Greek loyalty. These hostages were kept in Rome for a trial that never came. They were eventually permitted to return home, but only after seventeen years in captivity.

Polybius was among the hostages captured and transported to Rome. However, unlike his fellow Greeks, Polybius was fortunately treated well by his host Aemilius Paulus. The pair had met while on campaign and had become good friends. As a result, while in Rome, Polybius was hosted by Aemilius and tutored his two sons. Thanks to his friendship with Aemilius, Polybius not only avoided miserable living conditions, but he also had access to the elite of Roman society. From this perfect vantage point, Polybius was ideally poised to study the unique and unprecedented Roman Constitution.

From City to Empire: The Rapid Rise of Rome

By the time that Polybius was writing, Rome had expanded from a meager city state to an ancient superpower. In the beginning, Rome had few if any natural advantages; it was inland and therefore cut off from trade, located on infertile soil and surrounded by enemies. For years, the early Romans were a hardy, agrarian people who had to work extremely hard simply to sustain themselves. Traditional wisdom would predict a depressingly short history of liberty for the Roman people, who would eventually be dominated by their enemies due to their lack of resources. Against all odds, traditional wisdom was soundly thrashed as Rome progressed from strength to strength, overcoming their Italian enemies and expanding out into the wider Mediterranean. Many stunned spectators questioned how such an austere, agrarian civilisation had come to dominate the Mediterranean with such unprecedented success. Polybius sought to answer this question in his book, The Histories.

Polybius believed that Rome’s constitution was effective for two reasons. First, the constitution adapted to suit human nature and second, it stopped what he referred to as Anacyclosis, a cyclical theory of political evolution and decay.

Human Nature: Self-interest and Fear

Many ancient political theorists believed that political theory was limited by the nature of man. Therefore, any theory of politics must start with an examination of man’s nature and faculties. At first, Polybius believed that people were united due to their own weakness and fear. Thus, the strongest man among them rose to a position of power. This order resembled little more than the actions a herd of sheep or a flock of birds.

Humans cease to resemble animals when they begin to apply reason. According to Polybius, ‘when one human sees another wronged’, they ‘will notice the thing and be displeased at what is going on, looking to the future and reflecting that they may all meet with the same treatment’. They ‘will naturally be displeased and offended by such conduct, sharing the resentment of their injured neighbour and imagining themselves in the same situation’. Through moral imagination and sympathy, an idea of justice is formed. ‘Ferocity and force having yielded to reason’, the alpha transforms; what was an alpha now becomes a king.  Polybius’ account of the origins of justice bear a striking resemblance to the moral theories that Adam Smith would later articulate in The Theory of Moral Sentiments.

Polybius describes humans as rational and self-interested creatures. The duality of fear and sympathy rule our lives. As long as fear exists, people will cooperate and sympathise with one another, producing a stable society. Problems arise when members of a society lack the imaginative capacity to put themselves in the place of others. This results in the unsympathetic person practising little if any restraint and benefiting themselves at the expense of others.

Anacyclosis: The Cycles of Government

Polybius stated emphatically that ‘all existing things are subject to decay and change is a truth that scarcely needs proof; for the course of nature is sufficient to force this conviction on us’. According to Polybius, this maxim of nature can also be applied to political orders. This was not a new idea in Greek political thought. Aristotle believed in a cyclical theory of government in which each order begins pure but rapidly decays to its corrupted form. Polybius, akin to his fellow Greek predecessors, believed in a cycle of governments. For the Greeks, there were three kinds of government: monarchy (rule by one), aristocracy (rule by the few) and democracy (rule by many). These forms of government were distinguished as far back as Herodotus, writing in the fifth century BC.

Polybius believed that, like other animals, humans naturally formed a herd for the purpose of mutual protection. Given the nature of herds, ‘it is a necessary consequence that the man who excels in bodily strength and in courage will lead and rule over the rest’. This is why the cycle of political orders began with monarchy, the rule of one.

Monarchy to Tyranny

The first monarch would be an honorable man worthy of the right to rule due to his staunch upholding of justice. As a result, his rule would be respected even when his physical strength waned in later life. Sadly, this state of peaceful affairs would not last. As the king reaches old age, it would be necessary that he choose a successor to inherit his position. Because the first king had lived a life of hardship and toil, he would be an austere figure who conducted his leadership as a first among equals. Polybius wrote that the first kings ‘were exempt from all vituperation or jealousy, as neither in their dress nor in their food did they make any great distinction, they lived very much like everyone else, not keeping apart from the people’.

The successor to the first king would not prove so virtuous. Growing up in luxury and privilege, the new king would act as if he were superior to his subjects. His tastes would become excessive and offensive to the populace at large. He would eventually decay into a tyrant due to his lack of virtue.

Aristocracy to Oligarchy

Unable to bear the humiliation of injustice, the best of men would rise up against the new tyrant. These rebels would not usurp power for selfish gain since, according to Polybius, they were ‘of the noblest, most high-spirited, and most courageous, because such men are least able to brook the insolence of princes’. When they prevailed, harmony would once again be restored: ‘these chiefs gladly assumed this charge and regarded nothing as of greater importance than the common interest, administering the private and public affairs of the people with paternal solicitude’.

But yet again, the same issue would rear its ugly head, namely the problem of succession. The sons of these noblemen would not grow up to emulate their courageous fathers. Instead, ‘having no experience of misfortune and none at all of civil equality and liberty of speech, and having been brought up from the cradle amid the evidences of the power and high position of their fathers’, these petulant aristocrats would indulge in all kinds of greed, lust, and excess. Consequently, they would meet the same fate as the kings: a violent overthrow.

Democracy to Mob Rule

The people of this exhausted society had lost faith both in monarchy and in aristocracy. Since both rule by one (monarchy) and rule by the few (aristocracy) had proved to be unreliable systems, the new political order was to be based upon rule by the many, or democracy. As with all of Polybius’ political orders, democracy experienced its moment of flourishing glory.

For a time, the founders of this new democracy valued equality and freedom of expression.

The next generation, as always, proved problematic. Growing up in a society of equals, the new generation no longer valued the virtue of equality, instead aiming for preeminence. Problems arise when those who wish for preeminence ‘lust for power and cannot attain it through themselves or their own good qualities, they ruin their estates, tempting and corrupting the people in every possible way’. This new political order rapidly degenerates into violence and anarchy. Those who lust for preeminence band together and ‘massacre, banish, and plunder, until they degenerate again into perfect savages and find once more a master and monarch’.

The issue that Polybius outlines is the lack of continuity between successive generations. The justice of the monarch decays to the pride of the tyrant. The virtue of the aristocrat decays to the indulgence of the oligarch. The equality of the democrat decays to the greed of the mob. Unsurprisingly, this decline culminates in anarchy. Reverting once more to step one, the grim sequence begins again. Was there any solution to this miserable and eternal cycle?

The Greek Solution to the Cycle

Each system of government has its own virtues, but each has an inherent vice. Using the analogy a ship (borrowed from Plato) Polybius explains iron can rust, wood has its worms, and timber is subject to pests. Similarly, ‘each constitution has a vice engendered in it and inseparable from it’.  This theory of decaying cyclical affairs was common amongst Greek thinkers. Aristotle proposed the solution was to mix and blend the political orders together. By having a mixture of all of the orders, the vices of each are nullified. Aristotle and Plato aimed to eliminate disagreement and conflict while promoting harmony and unanimity. The idea that a mixed constitution would yield a peaceful society was an idea that dominated political thought in the ancient Greek world. Polybius departed from this conclusion drastically.

Polybius’ Solution

For Polybius, the point of politics is to preserve liberty through stability, not to create unanimity. This goal can be seen in his praise of the Spartan constitution which had left Sparta with ‘lasting heritage of freedom’. The cycle previously discussed is detrimental to liberty as it is constantly gravitating towards various forms of despotism. Thus this cycle needed to be halted and stability maintained.

How did the Romans preserve their liberty? One could argue the Romans were made great by their leaders of great personal and civic virtue. There are many examples throughout Roman history of selflessly dedicated and brave leaders such as Cincinnatus who gave up absolute power for a simple agrarian life. However, this was not why Rome succeeded. Polybius did not believe that virtue alone was enough to provide a stable and free society. When discussing Athens he disregards it as useful models to follow precisely because their moments of greatness were achieved by great men. Shortly after these great men perished or were ousted, Athens, according to Polybius, collapsed back into mediocrity, confusion and destitution.

Another issue for Polybius was that human nature not particularly malleable. Political theory has to adapt to human nature, not vice versa. Rather than blind hope for virtuous leadership which was not guaranteed, Polybius firmly believed in reliance upon good rules and institutions which preserve an orderly liberty.

If humans are as Polybius theorised self-interested animals driven by both fear and sympathy, the solution must be to institutionalize fear in order to promote sympathy. Instead of attempting to eliminate social conflict altogether, Polybius proposed that humans should aim to make conflict productive and useful. Fear can be institutionalized and conflict can be made productive by the combination of constitutional orders.

In another radical turn for his time, Polybius rejected the idea of a mixed constitution solution. A common mistake many people make is saying Polybius account of the Roman government is a mixed constitution. Polybius never uses the word mixed. Instead, he uses the words composition, arrangement, balance and equilibrium. Polybius’ ideal political order is not mixed like the ingredients in a cake. On the contrary, each piece is separate and distinct with different roles. This concept of separating power is the key to Rome’s success which Polybius describes as having dominion over nearly the whole world.

The Roman Government’s Innovation

According to Polybius, what did the Roman government look like? Polybius discusses three institutions: the Consuls, the Senate and the Popular Assemblies. Each embodied one of the three orders of government.

Monarchy is represented by the two Consuls. The Consuls had the power to command armies and presided over the Senate and the popular assembly. The Senate filled the role of the aristocracy.  It was an advisory council and ex-magistrates who were members for life. In theory, the Senate was merely an advisory body, but in practice, its powers extended to a variety of public policy issues. Domestically, the Senate presided over courts that required investigation, had power over tax revenue, and provided the main arena for political debate. On matters of foreign policy, the Senate was responsible for declaring war and negotiating with foreign ambassadors. Finally, democracy was represented by the Popular Assembly. Assemblies had the sole power to pass legislation, elect magistrates and even ratify or reject foreign policy treaties.

Unlike his predecessors such as Plato and Aristotle, Polybius did not aim to establish harmony and unanimity, rather than eliminate conflict he wishes to make it useful. By molding politics around human nature, Polybius’ account of the Roman constitution shows how conflict, since it cannot be avoided, should instead be utilized in the most productive manner possible for the common good.

According to Polybius’ account of human nature, we are fundamentally self-interested beings who aim to increase our power, however, we are responsive to fear. This is a key insight into why the separation of powers is essential to a lasting government. Each part of the government has a separate and distinct function. Because of the separate nature of each part of the government’s jurisdiction, each part will naturally fear the other encroaching beyond their proper limits. But this conflict is surprisingly beneficial. Polybius’ institutions will compete against the other in order to preserve their realm of power. Their mutual fear of losing their power will produce stability as each order preserves itself.

The Roman constitution also made it difficult for one particular group or individual to seize power. Each part of the government controlled a different area of life and each was interdependent on one another meaning neither could dominate the other wholly.

By spreading power out and giving each office a particular function, the Romans instituted checks and balances that guarantee an orderly liberty by stopping government overreach and decentralizing power. 

Polybius’ highly original idea of the separation of powers influenced myriad of political thinkers such as Machiavelli, James Harrington, Algernon Sidney, Montesquieu, John Adams and James Madison. His work is a masterful examination of the nature of political power and how the separation of powers can cultivate an ordered liberty that stands the test of time.


This piece solely expresses the opinion of the author and not necessarily the organisation as a whole. Students For Liberty is committed to facilitating a broad dialogue for liberty, representing a variety of opinions. If you’re a student interested in presenting your perspective on this blog, click here to submit a guest post!

Image: Pixabay

You may also like

Leave a Comment

* By using this form you agree with the storage and handling of your data by this website.