No discussion of the principles of Roman government was attempted until after Rome had become the greatest state in the world, and a beginning was then made by a Greek. Polybius (204-122 B.C.) was one of the statesmen who directed the policy of the Achaean League at the time when Macedonian power was destroyed and Greece brought under Roman control.
He favored a negative attitude toward Rome, in contrast to the pro-Roman leanings of the leaders of the League; and after the conquest he was taken to Italy as a hostage. There he became acquainted with the Roman constitution and the statesmen of the day, was sent by the Roman government on several missions to Greece, and spent most of his time in traveling and collecting materials for his History of Rome.
When Polybius wrote, the republican constitution had reached the height of its development and had not yet given way under the strain imposed by the expanding area and interests of Rome. The motive of his History was to explain the greatness of Rome, to trace the steps by which Rome had become the ruling power in the world, and to describe the manner in which control over her vast dominions was exercised.
In doing this, he presented a theory of the origin of the state and described the various types of government and the natural cycle of political change. He then analyzed the constitution of Rome, showing that, by combining elements of the various forms of government and establishing a system of checks and balances among the different organs, Rome was safeguarded against the decay that inevitably destroyed the simple type of state.
Polybius adopted the Greek classification of government into monarchy, aristocracy, and democracy, and held that each of these types might exist in a pure or a corrupt form. He believed that these forms followed one another in a natural sequence, each type containing within itself the germs of its own decay.
The earliest form of authority was a monarchy, based on force, established over a group of people bound together by natural instinct. As reason and experience gradually taught the value and necessity of government, and ideas of justice and morality appeared, the people obeyed the monarch willingly, and government proper was established in the form of royalty.
However, as the monarch assumed arbitrary power and ruled unjustly, this type tended to degenerate into its corrupt form, tyranny. Conspiracies, headed by distinguished and virtuous leaders, overthrew the tyrant and established aristocracy, Aristocracy, in turn, developed its inherent defect, oppressed the people, and became an oligarchy.
The people, rising against their oppressors, established themselves in power and for a time governed in the interest of the whole as q democracy. But dissensions soon arose, the wealthy corrupted the ignorant masses, injustice and discontent increased, and mob rule resulted. The excesses Of the mob brought some bold leader into prominence, who secured for himself autocratic power and gained popular support; and the cycle began its course anew.
Polybius believed that to insure stability and prevent these successive transformations, it was essential to combine the better elements of all these forms. This had been partially accomplished by Lycurgus for Sparta, and it had been even better worked out gradually by experience in the Roman system. In the Roman constitution the consuls represented the monarchic principle, the senate was essentially aristocratic, and the popular assemblies were democratic.
Moreover, each of these organs exercised some restraint on the powers of the others, no one being able to act effectively without the consent of all. Thus an elaborate system of checks and balances was created. While the writings of Plato and Aristotle contained some conception of the value of this principle, the Greek writers preferred a simple form of government, somewhat modified by traces of the other types.
Polybius was the first writer to make a clear statement of the advantages of a mixed form of government, and of the principle of checks and balances in constitutional organization. These conceptions were recognized in theory and in practice in later periods, and in a slightly changed form remain valid in modern political thought.
Polybius viewed the Roman state as an impartial spectator, and in his point of view was detached and rationalistic. He believed that the motive to action is self-interest, that statesmen must treat interests as natural political forces, that political life results in an equilibrium of such interests among different classes, and that individuals and classes must be controlled by a system of mutual restraints. His attitude bears some resemblance to that later taken by Machiavelli.
