Polybius and anakyklosis, the cycle of constitutions

Carthage burning, spring 146 BC

In the spring of 146 BC, Scipio Aemilianus stood watching Carthage burn. Polybius was next to him. By Polybius's own account the general wept, and said he feared the same day would come for his own city. The Greek beside him had already worked out why it would.

Polybius hadn't chosen to be there. Aemilius Paullus destroyed Perseus of Macedon at Pydna in 168 BC. The next year the Senate drew up a list of a thousand Achaeans, on the word of their countryman Callicrates. The charge was insufficient enthusiasm for Rome. They were shipped to Italy, and the promised court of inquiry never sat. Parcelled out among Italian towns, they were left there for sixteen years. By 151 BC, when the Senate got round to debating their release, fewer than three hundred were alive. Cato closed the argument. Did the house really mean to spend a day deciding whether "some old Greek dotards" were buried by Italian or Achaean undertakers?

By then Rome had made him a hostage, then a client, then a functionary. He got back from Carthage in time to watch Lucius Mummius sack Corinth that same year and dissolve the Achaean League. A commission of ten abolished every league assembly in Greece, then sailed home after six months. Polybius stayed. He was left to settle the local legislation of the Peloponnesian towns, one at a time. Book VI of his Histories came out of that job: a defeated administrator's account of why civilisations fall.

"Rust is the natural dissolvent of iron." Polybius, Histories VI.10 (trans. Shuckburgh, 1889)

Six constitutions, and the order they come in

His word for it is anakyklosis politeion, the cycle of constitutions. He sets it out in Book VI, written somewhere between the 150s and the 120s BC. There are six forms, in three pairs: kingship (basileia) and tyranny (tyrannis); aristocracy (aristokratia) and oligarchy (oligarchia); democracy (demokratia) and mob-rule (ochlokratia). One of each pair is sound. The other is what the sound form turns into on its own, given time.

The order is fixed. Rule by the strongest arises "without artificial aid", is refined into kingship, and rots into tyranny. The best men remove the tyrant and govern as an aristocracy; their heirs run it as an oligarchy; the people throw them out and rule themselves. Democracy decays in turn into ochlokratia. Polybius describes that stage physically: "tumultuous assemblies, massacres, banishments, redivisions of land", running on until the crowd "has once more found a master and a despot". "This is the regular cycle of constitutional revolutions", he writes at the end of VI.9.

Watch the definitions. A one-man government counts as kingship only where it is "accepted voluntarily, and is directed by an appeal to reason" (VI.4). A government of the few counts as aristocracy only where the powerful were picked on merit. Democracy takes more than a vote. It needs reverence for the gods, care of parents, respect for elders and obedience to law, all of it habitual. In each case the name stays put long after the behaviour it described has gone.

The engine is the second generation

What turns the wheel is phthora, decay, and Polybius insists it comes from inside. "Rust is the natural dissolvent of iron", he writes at VI.10. Wood-worms and grubs do the same to timber, working "without any external injury". No invader is required.

Inheritance is the mechanism. Early kings, on his account, built strongholds and kept their dress and food much like everyone else's. Then the office became hereditary. Heirs found every necessity ready to hand and "gave the rein to their appetites". They decided rulers must wear different clothes and eat elaborate food, and the kingship became a tyranny (VI.7). Democracy dies on the same schedule. Those who remember the oligarchy prize equality and freedom. The rot starts once the constitution "has descended to their children's children" and long habit has made freedom cheap.

Stated as a rule you could apply, it has three conditions. A regime's claim on power rests on some performance the founders had to deliver: courage, or resistance to the last set of thieves. Power then transmits by birth or by habit. That tests for nothing. Successors grow up inside the security and surplus the performance bought, so nobody ever makes them produce it. Polybius thought this good enough to forecast with. Get the principles right, he says at VI.9, and you may miss the dates but you'll rarely miss the stage.

Why Rome was exempt, and for how long

Rome escaped the wheel. It escaped by not being any one of the six. Polybius calls it a politeia symmikte, a mixed constitution, and describes it as it stood in 216 BC, the year of Cannae. Consuls hold what looks like royal power; the senate controls the treasury; the people ratify treaties and hear the accounts of magistrates leaving office. His test for the mixture is the confusion it produces. Not even a native, he says at VI.11, could tell "whether the constitution as a whole were an aristocracy or democracy or despotism".

Nobody in the system can act alone. A consul in the field looks absolute. He can't get his legions corn or pay without a senate decree, and he needs the senate again for the money for his triumph. The senate can't execute a citizen without the people's ratification, and if the tribunes interpose their veto it can't even meet (VI.16). Everyone is short of something.

The exemption has a term. At VI.57 Polybius gives two sources of decay: one external, admitting "no certain or fixed definition", the other internal and following a definite order. A state that reaches "a high pitch of prosperity and undisputed power" grows extravagant in private life and fiercer than it should be about office. Candidates ruin their estates buying the people. The people are bought, then flattered, then cheated. They stop accepting merely equal power with their leaders and demand the lot. The constitution then takes "a new name, which sounds better than any other in the world". The name is liberty. What it names is "that worst of all governments, mob-rule". He wrote that forecast in Rome, about Rome, in the house of the family that had destroyed Macedon and Carthage.

Forty books, and the cycle appears in none

Polybius's best commentator made the standard attack. F. W. Walbank, in A Historical Commentary on Polybius, Volume I (Oxford, 1957), showed that Book VI welds together two things that don't fit. One is an inherited Greek philosophical cycle, Stoic or Peripatetic in origin and plausibly reaching Polybius through Panaetius. The other is a close description of Roman institutions, gathered at first hand. The seams show. Half of it is school philosophy about nature and necessity. The rest is reportage about corn supply and vetoes. The weld is asserted.

A sharper version of that objection is internal, and it's the one I can't answer. Polybius wrote forty books, and the six-stage sequence runs in none of them. Rome doesn't traverse it. Neither does Carthage, Sparta, Macedon or his own Achaean League, all of which he narrates at length. At VI.9 he promised that a man holding these principles would rarely mistake the stage a constitution had reached. That's a claim about prediction. His own history never cashes it. You can rescue the cycle by calling it an ideal type, a shape no real state has to fit. That rescue gives up the thing that made it worth having.

Matthias Gelzer supplies the other standing complaint. What Polybius files under the popular part of the constitution looks different from the inside. It looks like an oligarchy of nobiles, the office-holding families. Gelzer drew that picture in Die Nobilität der römischen Republik (1912): a narrow circle running the state through personal obligation. Fergus Millar spent the 1980s and 1990s pushing the other way, restoring real sovereign power to the assemblies. John North went back over the same ground in 1990. This one I find weaker. Polybius was cataloguing formal powers, and the formal powers were real: the senate did control the money, and a tribune really could stop it meeting.

What the model is still good for

What survives is a direction of causation. Decay is homemade. In Book VI, decline is manufactured by success and by succession, by the habits of people who never had to earn what they inherited. Foreign enemies get one clause at VI.57. They're the source of decay that admits of no fixed definition. Anyone who wants to blame a collapse on invaders or migrants has to get past that clause first.

The afterlife was enormous. Cicero took the mixed constitution into De re publica. Machiavelli rebuilt the cycle almost intact in Discourses I.2. Montesquieu inherited it. The American founders' talk of government parts checking one another comes down the same line. Not bad for an argument its author never demonstrated.

Names are where Book VI still bites. A constitution can pass into its worst form while picking up the best available word for itself. The people doing it will believe the word. The name outlives the thing. Polybius set that down while employed in the Peloponnese, writing local statutes for towns whose league had just been abolished by the men he was living among.