Plato to Polybius on Constitutional Change - Melissa Lane

This lecture was recorded by Melissa Lane on the 28th of May 2026 at Barnard's Inn Hall, London

Melissa Lane is the Class of 1943 Professor of Politics, Princeton University and is also Associated Faculty in the Department of Classics and Department of Philosophy. Previously she was Senior University Lecturer at Cambridge University in the Faculty of History and Fellow of King’s College, Cambridge.

She studied for her first degree in Social Studies (awarded summa cum laude) at Harvard University, and then took an MPhil and PhD in Philosophy at the University of Cambridge, where she was a student at King’s College, supported by appointments as a Marshall Scholar, Truman Scholar, and Mary Isabel Sibley Fellow of Phi Beta Kappa.

Professor Lane is an author, lecturer and broadcaster who has received major awards including being named a Guggenheim Fellow, and the Lucy Shoe Meritt Resident in Classical Studies at the American Academy in Rome. She has published widely in journals and authored or introduced nine major books including Greek and Roman Political Ideas; Eco-Republic; and most recently, Of Rule and Office: Plato’s Ideas of the Political, which was awarded the 2024 Book Prize of the Journal of the History of Philosophy.

Professor Lane is the only person ever to have delivered both the Carlyle Lectures and the Isaiah Berlin Lectures at the University of Oxford.

The transcript and downloadable versions of the lecture are available from the Gresham College website: https://www.gresham.ac.uk/watch-now/plato-polybius

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Transcript

SPEAKER_00 0:06

Let's begin with this question. Who is so indifferent or indolent as not to wish to know by what means and under what constitution the Romans in less than 53 years succeeded in subjecting nearly the whole inhabited world to their sole rule, a thing unique in history. Well, none of you here or watching online is so indifferent or indolent as not to wish to know. And this is the question that we'll be following Polybius in answering this evening. So Polybius was an historian who lived through most of the second century before the Christian era or before the common era. He was writing in Greek, his mother tongue, framing this extraordinary period of history through which he lived. So Polypius observed that rise of Rome from a succession of ringside seats. He was a political leader in the Achaean League of Greek cities, who then was one of a thousand hostages captured and taken to Rome. But he made a new life for himself there as the tutor and friend of a boy who would grow up to be Publius Scipio Emilianus, who would command the Roman army that raised Carthage with Polybius by his side. So that was in 146 before the Common Era, the same year in which Rome also destroyed Corinth, one of the leading Greek cities. So that symbolized the subjection of Greek independence across the board. So Polybius lived through the destruction of the Greek cause, which he had spent his youth serving. And so later in his life, living in Rome, he comes to write his histories. And that's the work on which we'll eventually be focusing as we get to Polybius from the classical constitutional thinkers of earlier Greek times. But for Polybius, while living in Rome, what he wanted to help his readers to do was to answer that opening question: how is it that the Roman constitution was framed so that it allowed the spectacular rise of Roman power to near-world conquest? And so Polybius would contend that the Roman constitution came to be distinctively stable in a way that enabled this remarkable achievement. And so we can begin by asking with him, why was a stable constitution so important? And his answer would be that only this can ward off the dangers of what the Greeks called stasis. Stasis is a term that can refer to factional division within a political unit, but it can extend as far as full-scale civil war. The same word can capture both. And so the whole history of ancient Greek constitutional thinking was concerned with how constitutional stability could be achieved, how stasis could be avoided. Plato, for example, in his Republic would dramatize the image of constitutional stability as in the terms of a circle. Plato writes, if one time the Constitution is set in motion well, it will go on growing, go on as if growing in a circle. This is because a stable constitution reproduces itself through the values and beliefs of its citizens that remain in sync with the values at which the constitution aims. And so constitutional stability on the left, then, is contrasted with constitutional decline. So a stable constitution can avoid decline, which would be a kind of corruption, a corrupting of the constitutional principles of the structure into another form, a worse form, if it's a form of bad constitutional change. But Polybius would come to believe that that dimension, that was this long-standing preoccupation of Greek thinkers with the stability of the constitution, was insufficient to answer his opening question about the spectacular growth of Roman power. So he added a second column, the column on the right, this question of the stability of state power. And the valence of that column was more complex. It could be more mixed. So on the left, all Greeks thought a stable constitution was a benefit, in fact, was a crucial political aim to be achieved. But on the right, the question of the stability of state power is something one might take a more nuanced form in conceiving. So you might think of stable state power, for example, as opposed to growth. So then stability looks like a kind of stagnation against state power's growth, the expanding rule in wealth, as indeed Polybius had observed in the case of Rome. So we'll see this distinction between the stability of the Constitution and then the stagnation versus growth of state power playing a role in Polybius' thinking throughout the lecture. And in particular, it will be central to his comparison between Rome and Sparta. So we'll see that he thought that in an important way, both cities had the same kind of constitution. We'll see that that was called a mixed constitution. But he argued that it ended up working out in different ways across those two dimensions. And that was because of the specifics of the customs and laws that each state enjoyed. So the specifics of Sparta made it more prone to stagnation, whereas the specifics of Rome would be what enabled it to become an imperial power par excellence, conquering so much of the globe. So we can see this in this chart that I put together, and let me help you decode it. So let's start with the top, well, the middle row, the second row, which is the row about the stability of the constitution. So you can see that on Polybius' understanding, both Sparta and Rome enjoyed a stable constitution. They had come to enjoy a stable constitution. But eventually, in each case, the constitution might become corrupted. So it wouldn't be stable forever. Other observers had thought this happened to Sparta before Polybius' lifetime in the fourth century before the Common Era. Polybius would project that for Rome into the far future. And we'll see towards the end of the lecture, Polybius prophesying the fall of the Roman Republic. But let's now look at the columns. So you can see that Sparta falls 100% in the column of stagnation or decline. It did have a brief moment of superiority in the 5th century BCE, but by the time of Plato and Aristotle, at least, it was seen as stagnating or even declining state power. It revived a bit by Polybius' time, but it never really started to expand again. Whereas Rome is all in the column with the growth of state power. So Roman power explodes in Polybius' lifetime, that's the less than 53 years. But the question is, what will happen at the end when the Roman constitution declines eventually, when the Republic will ultimately fall, as indeed it would, what would happen to Roman power? And we'll see again at the end of the lecture that it too will ultimately collapse. So tonight's lecture then will follow Polybius himself in moving back and forth between Greece and Rome. So in the first third of the lecture, I'm going to introduce Greek constitutional thinking more fully. And then in the second part, we'll look specifically at Plato, Aristotle, and others on the idea of the mixed constitution and specifically on Sparta as a mixed constitution. And all of that will then prepare us for the third and final part when we'll bring this back to Polybius and we'll look at Sparta, Polybius on Sparta and Rome. Okay, so let's step back then to the beginnings of constitutional theorizing in ancient Greece. And we can do that though, even with a question through Polybius' own eyes, because here Polybius tells us why we have to think about constitutions at all. So you can see him writing that the chief cause of success, or the reverse, failure in all matters, is the form of a state's constitution. Springing from this is from a fountain head, all designs and plans of action not only originate, but reach their consummation. So Polybius embodies a tradition in which the form of a state's constitution is the chief cause of its political success or failure. And so that's why I'm giving this lecture tonight in the middle of my series on political crises in Athens and Rome, and more broadly in Greece and Rome. Because if we want to understand political crises, then we have to ask do such crises especially afflict certain kinds of constitutions? And conversely, is there a special kind of constitution that's more than any others built to last? And again, the spoiler we'll see in a few minutes that that will be the mixed constitution. The mixed constitution is the most stable, and so it can be responsible for the greatest success, although the perfection of that success was reached in Rome. So the terms of this debate were set out by the historian Herodotus back in the fifth century before the Common Era. And Herodotus introduced this vocabulary that would become absolutely fundamental to all later Greek thinkers. And it's a distinction between three simple constitutional types. So you can see rule by one person, so that's from the root for one, a single ruler or office holder. The arch ark root means rule or office. Rule by an elite few, allegoi, the few, rule, again, arche. And rule by the many. And you can see that this is a different root, the demos, the many, the people, enjoy power, kratos, from which we have democracy. And Herodotus's characters flesh out the strengths and weaknesses of each type. So a monarch might be able to have good judgment, but they might make arbitrary decisions. An oligarchy might have a good education among these elite educated few, but they might fall prey to internal quarreling. And a democracy, in turn, might be liable to fall into demagogy and populism. So each of these simple forms might have a tendency to turn into something bad. And so the next move in this tradition then was to go from three to six. And this is actually done by Plato, but I've given you Aristotle's version, which is very close. So you can see on the left now we have one few many, that sort of basic triad that Herodotus had given us. But now we have a good version. So the good version of one is kingship, but that might collapse into a bad version of tyranny. Good rule by the few aristocracy, bad rule by the few oligarchy, good rule by the many. So Aristotle uses the term polity for that, and he reserves here the word democracy for bad rule of the many. So you can see now that we have the prospect of constitutional change moving horizontally across each line. A kingship might degenerate into a tyranny, an aristocracy might degenerate into an oligarchy. So we've introduced dynamic change into our classification of constitutions. Okay, so how can such declines be avoided? So the answer that we're going to be looking at is mixing these types. So if we can combine the one few and the many, then the thought will be that that mixture might have the strengths of each, the strengths of one, the strengths of the few, the strengths of the many, but without falling prey to the corresponding weaknesses. So the idea is that a mixture can counterbalance and stave off the weaknesses while still giving us the good judgment, perhaps, of the king, the good education of the aristocracy, and perhaps also the freedom and concern for popular participation of the many. So now we need to do just a little more analytical work before we can put all of this into practice. Because we have to ask, okay, then, how do you mix the elements of a constitution? What are the different ways that we might mix the one, the few, and the many? So here's a non-ancient set of images for three modes that the ancients are going to explore. And I've named them blending, as in a smoothie, compresence, so the vegetables and vegetable soup, they're all there, but they're not really interacting. And then active counterbalancing, here's an American example, the savory peanut butter, checking the sweetness of the jam. So let's just see how each of those works with a Greek theoretical example. So, first of all, blending. So the idea of blending is that you're mixing the elements as if into a cake so that you can no longer separate them out, as if it's a cake batter. And Thucydides can be seen, so one of the historians of Athens writing in the late fifth century, can be seen in a particular moment in his history as celebrating a mixed constitution in terms that I think probably implied blending. It's a little bit difficult to tell, it's a brief passage, but he talks about a constitution. This is, um there had been a sort of full-fledged oligarchy that had taken over from the democracy in Athens, and then the oligarchy kind of softens and expands its remit a little bit and becomes this mixed constitution, a balanced mixture of the few and the many. So let's consider that blending. So that's blending. Now, what's the second kind? Well, the second kind I called compresence, and we can unpack that as passive counterbalancing. So, like the vegetable soup, what we mean by that is that the elements are separately and independently remaining present. And Aristotle gives us a good example of this. So he talks about how can we have a just mixture of oligarchy and democracy, and we can do that by combining elements from both. And his example was different fines levied in different terms and to give different incentives to the rich and the poor to participate or not participate, and so balance each other out. So all those different kinds of fines would be present and operating at the same time, but they're not really interacting, they're just kind of there as compresent elements. That's Aristotle's reference. And okay, so now we have the first two, and now we add the third. So the third is going to be where Polybius will really focus, and this I've named active counterbalancing, and we'll see that that label is very much at home in his own vocabulary. So Polybius and possibly some earlier thinkers thought of the mixed constitution in Sparta and Rome in this way. And so you can think of this as a kind of complex pendulum. So imagine that we have these different weights, and each is swinging in its own orbit, but with the power to move out of its orbit. Perhaps the pendulum tilts on the ground, and so the orbits might be knocked out, but then the other element will knock the one that came out of its orbit, it will get knocked back into shape. So the different pendulum weights will check each other and therefore restore the balance of the pendulum overall. So that's the act of counterbalancing. The elements are not just there together, but they're actually checking and correcting each other. Okay, so that's where we're going with Polybius on Sparta and Rome. We're going to see that working out in practice. But before we get there, I want to just say a little bit more about how Sparta was thought of by thinkers before Polybius, especially Plato, Aristotle, and some others, because that will prepare the ground for us to think about Polybius' account. So Sparta matters in this story because Greek thinkers themselves already recognize that it didn't really fit well into the three simple types, or even the six simple types, either the good or the bad. And that's because the Spartan constitution was more complex. So it had these three elements within it. On the one hand, on the left, you see something that was an adaptation of the principle of rule by one. Actually, the Spartans had rule by two as that element. They had two kings, very unusually, each from a different royal house, who were ruling at the same time. But that's a kind of equivalent to monarchy, literally, one king in this case, too. In the bottom middle image, though, we also have an element of rule by a few. The Spartans had an elected council of elders who once elected served for life. And they had an element of rule by the many. They had a citizen assembly, which voted, as Thucydides said in the word translation of Paul Cartilage, by shouting and not by ballot. So the citizen assembly gathered and they shouted to indicate yay or nay on a given resolution. So one few many in Sparta, the Spartan constitution was inherently mixed. And I think the idea of the mixed constitution really starts to develop as people think about this actual constitution of Sparta. It made it not just an academic question, but a kind of real live question. Okay, so how do Plato, Aristotle, and a few others then talk about Sparta? And I'll spend a few moments on this before we get back to Polybius. So Plato, for his part, would talk about Sparta in a couple of interesting ways. So on the one hand, this is a sequence dramatizing book eight of Plato's Republic. He gets interested in the idea of thinking about the specific laws and customs that give Sparta its special qualities. So in this diagram, Sparta is the democracy. And you can see that that's a kind of regime that we haven't met yet. We haven't seen that word. Plato actually coins it in the Republic in this passage. But he puts it in a kind of sequence of other simple regimes. You can see that all of Democracy and tyranny, those are all the few, many, and then the sort of bad one. We've met all of those before. Plato sticks Sparta in in order to really focus on what was special about it. What was special about it was its obsession with military victory, training for military success, and eschewing the accumulation of wealth among the Spartan peers. And that meant that for Plato, then, he says explicitly this democracy corresponds to the Laconian, that's a way of referring to the Spartan core land that they occupied. So this corresponds to the Spartan constitution. So we can see that now in this context, Sparta has a simple constitutional type. It's a special one. And what's special about it, it's officially aiming at honor, but, and this is its characteristic flaw in this picture, the office holders, the rulers, and the Spartan peers secretly desire gold and silver. So the official laws of the Spartan constitution say they should not be accumulating Spartan wealth. Their currency is iron, not gold and silver. But Plato is observing and suggesting well, actually, though, these people will start to desire gold and silver, and that will be the seed of corruption of the Constitution. So the democracy itself will start to decline actually into a kind of oligarchy. And here Plato was actually among a number of other observers at the same time who were pointing this out. So for example, Xenophon says in former days the Spartans were afraid to be found in possession of gold because it would get was against the law. But nowadays, in the fourth century, as he's writing, there are some who even boast of their possessions of money. Okay. So on this account, the Spartan constitution has this kind of inbuilt flaw. It's tending towards decline. And in another work, Plato then would say, well, it was a mixed constitution. It was trying to mix the democratic and the monarchical. It was trying to kind of blend those together. But ultimately that blending failed. And that's really when the decline set in. So the elements that were supposed to be blended didn't really succeed. And so it was trying to be mixed, but ultimately it failed. Okay. Now Aristotle will pick up this idea from his teacher Plato that Sparta had a mixed constitution, and he will use that idea to talk about mixing now not as blending, but as compr presence. Remember that passive counterbalancing. So Aristotle says, well, the defining mark of a good mixture of democracy and oligarchy is when you can speak of the same constitution, both as a democracy and as an oligarchy. And this is just how things are in the case of the Spartan constitution. So, but what he means by this is it's a duck rabbit scenario. You can look at the Spartan Constitution and see it as a democracy, you can look at it and see it as an oligarchy. So what he actually has in mind here is not blending, it's that there are institutions of both kinds. But Aristotle again sees, yeah, but Sparta has that same Achilles' heel that Plato and Xenophon saw. And what is that same Achilles heel? It's that some of the Spartans came to own far too much wealth and others too little. And so it really moved into an oligarchy rather than having that democracy element where all the Spartan citizens at least had equal possessions. Okay. So for Aristotle, again, the Spartan constitution was mixed, but it was imperfect. It had worked for a while, but already by his lifetime and that of Plato and Xenophon, it was kind of breaking down. So I just want to add one last text. This is a much less familiar text, and we don't know for sure who wrote it. Um, it's attributed to a contemporary of Plato named Architas, a Pythagorean philosopher. Some scholars think it may actually be by a student of Aristotle. So this most recent translation suggests that it may be by a student of Aristotle. So it's clearly in the same time period that we've been discussing. And what's interesting about it is that you can see that it says that better law and state should be a synthesis, a mixture of all other political constitutions, just as it is in Sparta, and that makes it strong and durable. So you can see the same idea. Sparta is a mixture, it has those three elements: the kings, the council, and the assembly, and that makes it a mixture, and that makes it a strong and durable constitution. Okay, so let's now come to Polybius on Sparta, and that will bring us then to Polybius in a few moments on Rome. So Polybius now introduces this third type of counterbalancing in a mixture, um, the active counterbalancing. And here you can see it very explicitly in his language. So here he's talking about a mixed constitution and specifically about Sparta. So he says the force of each element is neutralized by that of the others, so that none of them should prevail and outbalance another. So that's my pendulum imagery. What we're trying to prevent is that one weight on the pendulum tips over and pulls the whole thing off its balance. That's what we're trying to prevent. And the way it's prevented is that each element is neutralized by the other when it might tend to overbalance. Now I'm using that mechanical imagery. Polypius actually used natural imagery. Um, he described, and this is a very famous passage, still talking about Sparta, but sort of also talking more generally about mixed constitutions and constitutions in general, here more the simple constitutions. He says, he compares it to rust in the case of iron and woodworms in timber or wood. So rust is inherent to iron. It's not a vice that comes from the outside. It's a tendency that iron always has to rust. It might tip over into that bad form. Right? So this is so he's dramatizing with this imagery. So each constitution has a vice engendered in it and inseparable from it. The vice of each constitution is part of its nature. That's what we have to try to balance. So that's each simple constitution, but the mixed constitution will achieve that balance. It will prevent the rust, it will prevent the rot from setting in. And so the idea is that each of the three elements would check the other, and this is how it will work. And we can see this spelled out in another author, um, Plutarch, um, who is talking about the Spartan lawgiver Lycurgus, to whom everyone in the tradition credits these Spartan laws, the Spartan constitution. And Plutarch is writing about 250 years after Polypius, but he's making the same argument. So he says he credits Lycurgus with mixing the polity of Sparta. You see exactly the same language, very explicit, mixing the polity, meaning there, the constitution. And he gives the example. Well, for example, the Senate is the ballast. So now we have another mechanical image, right? You have a ship of state and it needs ballast to prevent it from tipping over. And so he spells that out. Um, for example, the 28 elders always took the side of the kings when the democracy needed to be curbed. But then on the other hand, if there was a tendency toward tyranny, they would strengthen the people. So the elders, the council of elders, are the ballast, they're the balancing force. They tip one way to check the kings, and they tip the other way to check the people, and vice versa. Okay, so you can see how this constitutional theory would be long-lived. Um, indeed, um this tradition, as I'll say briefly in conclusion in a few minutes, would uh continue to inform the ways that political thinkers understood the prospects of constitutional stability and change. Okay, so back to Polypius, and now Polybius on Rome. So now we're going to move from everything we've learned so far about mixed constitutions and Sparta and now see how Polybius applied all of this to Rome. Because remember from my opening question, his larger project was to explain the rise of Roman power. Remember that opening question? Um, who could not wish to know by what constitutions the Romans in less than 53 years succeeded in subjecting nearly the whole world to their sole rule, something that was unprecedented in history to that time. So, what's his answer going to be? Well, it's going to be Rome too was a mixed constitution, but it was different from Sparta in two specific ways. So Polybius spells this out. So, first of all, unlike Sparta, which had that single great lawgiver like Kyrgyz, to whom everyone credited all these great achievements, Rome was trial and error. The Romans achieved the mixed constitution not by having a great lawgiver who laid it down, but through the discipline of many struggles and troubles. And Polybius spells out, for example, remember, they were defeated by Hannibal, the ruler of Carthage, at the Battle of Canae in 216 before the Common Era, just before this huge explosion of Roman power really took off. So it was that failure that kind of led them to figure out the mixed constitution as they went along. So by Polybius' lifetime, they had gotten it right, it was stable, but it had to come into being as again a kind of natural growth, not as a kind of artificial design. So you see him again here saying they always engaged in choosing the best, by light of the experience, gained a disaster, and they reached the same result as the Spartan Lycurgus, the best of all existing constitutions. But, and here's a little video of the growth of Roman power. You can see here the end of the fourth century before the Common Era. Here's Rome as the hegemon of the Italian peninsula on the eve of the Second Punic War. The beginning you see Rome's power spreading here, Rome after the final victory into the first century. This is Caesar, Pompey, the death of Julius Caesar, the very end of the Republic, Augustus, the conquest of Britain and the reign of Vespasian, the territorial height of the Empire, the end of the Pax Romana, the crisis of the third century of the Common Era, the later empire, and so it goes on. Here we have about to have the partitioning into the Western and Eastern Empires. And so this history concludes. So that video was to dramatize for you again the other big difference between Sparta and Rome that we've already identified. Namely, Sparta stagnated in its power, Rome exploded in its power, in its territory, and its wealth, as the video just dramatized. So this is what Polybius is now going to explain. He's going to say, okay, part of the answer is mixed constitution, but Sparta had a mixed constitution. They didn't conquer most of the known world. So how did Rome do it? So now he's going to draw the distinction. So here he says, for the purpose of remaining in secure possession of their territory, the legislation, the legislation of Lake Kyrgyz is amply sufficient. So they can stagnate or remain stable in their power, but they're not going to grow. But if anyone is ambitious of greater things to rule, to lead the world, then it must be admitted that from this point of view, the Laconian Spartan constitution is defective, while that of Rome is superior and better framed for the attainment of power, as we see from the actual course of events. So this is now the actual specifics that we need to explain. Okay, so now we go back to the same building blocks. We have in Rome the monarchical element, not kings, but elected consuls who exercised authority over all public affairs and commanded the armies. We have an aristocratic element, the power of the few, the senate, who controlled the treasury, received ambassadors, investigated some public crimes. They didn't, however, pass laws. That was reserved to the democratic element, the element of the many, the popular assemblies passed laws and could confer honors and punishments. Now, what Polypius then says is these three elements in bad times will cooperate. They will all see that the state is in danger and they'll bring their distinctive strengths to bear, and that will give the state good judgment, good leadership, wise counsel, and popular freedom and authoritative laws. But in the good times, that's actually when the checking and counterbalancing is going to kick in. Because the good times, the times of prosperity and power, that's when each given part might be, he says, corrupted by flattery and idleness and start to wax insolent and overbearing. And that's when the act of counterbalancing is going to kick in. So this is a long quotation, so I'll kind of highlight parts of it. So when one part, having grown out of proportion, tends to become too predominant, that can be counterworked, counterbalanced, as it were, and thwarted by the others so that none of them will excessively outgrow the others. So now the image is again natural. It's more like one part might threaten to grow into a tumor, and the other parts can sort of kick in and prevent that. And so for Polypius, then Rome succeeded in passing Aristotle's test. He says it was impossible even for a Roman to pronounce with certainty whether the whole system was aristocratic, democratic, or monarchical. It was mixed. Again, it was a duck rabbit. You could see it as any one of these. You had to see it really as all three. So this idea that Sparta and Rome were different in some crucial way, even within the mixed constitution, would be picked up in the 16th century by Niccolo Machiavelli, who really is studying the Roman constitution, especially in the writings of Polybius and Livy. And Machiavelli says, well, in Sparta, the guardianship of liberty was entrusted to the nobles. So he wants to say in Sparta, the few, the council, was the most powerful. And remember, we saw Plutarch also emphasizing the council in Sparta was the ballast of the ship of state. So Machiavelli is in that tradition of saying, really, in Sparta, if if you had to pick one that was in charge, it was the nobles. But he says in Rome, it was the popular element, it was the plebeians. And so it was the plebeians who really wanted liberty, wanted wealth, wanted power, most of all wanted liberty. And that was what drove then the expansion of Rome. So it's a similar story to Polybius. The contrast between Sparta and Rome helps to explain Rome's remarkable growth. Okay, we're almost there. One more point about Polybius, and then a very brief conclusion about how his work has been received. So the final part of Polybius that I want to introduce is his organic language again of what he called the cycle of constitutions. So he coins this idea of a cycle of constitutions. And it's again that organic life cycle element, just like the rust with iron or the worms in wood more organically. So he talks about the course appointed by nature in which constitutions change, are transformed, and finally return to the point from which they started. And remember that we haven't seen a cycle in any of the thinkers before Polybius. None of them actually saw you going back to the beginning. You might go horizontally from kingship to tyranny, from oligarchy, from aristocracy to oligarchy, but you didn't ever go back to the beginning point. That's what Polybius actually gives you. So there's actually two ones here because there's sort of two starting points. The one on the left is the rule of the strongest, but it's not yet a kingship. But then it goes from that into the kingship, then we go across, as in the six-fold scheme, right, to tyranny, but then that goes down diagonally left to aristocracy, that turns into oligarchy, that goes diagonally left into democracy, that goes into government by force, and that takes you back to zero or the original one, the neutral or primitive constitution. So it's a cycle that he says if you have just these simple forms, we'll keep repeating. So where in that cycle is the mixed constitution? Well, it's outside the cycle. That's the whole point of the mixed constitution, remember? It can achieve stability. It can stabilize so that you don't have to go through that decline. You don't have to have the failure and corruption. You can actually stabilize, you can stand outside history at least for a time. And yet, Polybius reminds the reader that even the mixed constitution is natural. It too is organic, it too will ultimately die. And this is that moment of his prophesying the death of Rome that I mentioned at the beginning. So he says, when a state has weathered many great perils and attained to supremacy and uncontested sovereignty, that's Rome in his lifetime, world conquest, affect not, of course, the whole world, but so much of the world, supremacy and uncontested sovereignty. But what happens then is you get the explosion of greed and political rivalry. You get that tendency to stasis, to faction, that a stable constitution needs to be without. So life becomes more extravagant, the citizens become more fierce in their rivalry, they love office, again, they become extravagant, they get puffed up by flattery. That's towards the bottom of that quotation. And now they will no longer consent to obey. So the popular element in particular is going to become too greedy and demand the lion's share for themselves. And when this happens, Polybius says the state will change its name to freedom and democracy, but it will change its nature to the worst thing of all, mob rule, okay, the power of the mob. And this may be a word that Polybius himself actually coined. So this is sort of interesting because what it suggests is what happens in the mixed constitution is really that the democracy part goes bad. The democracy part, which should be on that bottom right, becomes mob rule. It becomes populism, as we might say today. And that is then the kind of corruption of the mixed constitution. Because one element goes bad, the whole thing ultimately collapses. Okay, a very brief conclusion. So why does Polybius matter? Why is it important to understand his account of constitutions? Well, it's gone on speaking to political thinkers through the centuries. And I want to end with two slides that contrast two very different takes on Polybius' ideas and the mixed constitution. So one take is that the mixed constitution was good, but it didn't go far enough. It didn't get all the way to the separation of powers, which would be its kind of perfection. So one critic of Polybius, a scholar of Polybius, has said this. He says, Polybius says Rome had actual powers, these three different powers, but they didn't have legal competences. They couldn't sort of legally check each other. It was more just throwing their weight around. And John Adams, one of the American founders, would say the same thing. He would say, three orders, three constitutional elements can never balance each other unless each in its department is independent and absolute. So Adams would call for a veto of each on the other, a legal veto, a legal competence to veto, which was missing in Rome and which Polybius didn't see was necessary. So that's the sort of good side. The mixed constitution was good, but it didn't go quite far enough. Against that, we have others who see the very idea of the mixed constitution as a snare and a delusion. And this was Thomas Hobbes, for example, in chapter 29 of his Leviathan arguing that this is not even a government at all. It's not a real constitution at all. It is simply factions. So it looks mixed, we say it's mixed, but it's really just three factions fighting it out. It hasn't achieved a balance. That's a mistake. So Hobbes thinks that the mixed constitution was actually a recipe for the very stasis, the factions in civil war, that it was pretending to cure. Now, to my mind, Hobbes goes too far. As the philosopher Philip Pettett has recently defended in his work, The State, the mixed constitution against Hobbes's claims, I think, is a real possibility. It is a constitutional kind. But the moral of Polybius is that I think we shouldn't put any particular kind of constitution, including the mixed constitution itself, on a pedestal beyond criticism. The deepest lesson of Polybius is that no constitution is immune to corruption. Constitutions alone cannot be guaranteed to protect freedom. And so in my next lecture on the 11th of June, we'll see how Cicero learned this lesson, paying for it with his life. Thank you very much for your attention.