It is useful and necessary to study different types of regimes and to determine which is the best and alsosince the best may not always be possiblewhich is the best possible regime. Such knowledge is also useful for existing regimes so that legislators can see what types are laws are suitable for their regime, since laws need to made with a view to the regime.
The worst regime is naturally that which deviates from the "first and most divine" regimekingship. Tyranny is therefore the worst regime and democracy is the least bad of the deviant regimes.
There are different types of regimes because there are many parts to a city. Among the city's inhabitants there are differences in wealth, trade, virtue, family and so on. The regime is simply the arrangement of offices, and different cities arrange their offices in accordance with which group in the city is preeminent. The two main types of regimes that exist are democracy and oligarchy, since people consider aristocracy to be a sort of oligarchy and "so-called" polity to be a type of democracy.
Democracy is not simply the rule of the multitude, since in every regime the majority has authority. The distinction between democracy and oligarchy is that in "democracy exists when the free and poor, being a majority, have authority to rule; oligarchy, when the wealthy and better born have authority and are few."
Cities are composed of several parts. The first is the part concerned with sustenancethe farmers. The second is the "vulgar element," the artisans. The third the "marketing element"those concerned with commerce and trade. The fourth is the "laboring element," and the fifth is the "warrior element." There are also the "well-off," who help the city by means of their property, and the "magisterial element" who are the city officials. While it is possible to be a part of several elements of the city at once, one cannot be both rich and poor at the same time. Therefore the different parts of the city are often considered just in terms of the rich and the poor.
There are several kinds of democracy. The first sort is based particularly on equality, where the poor and the well-off are treated equally and the majority rule since both groups have equal authority to rule. Other kinds of democracy include having the rule of law but allowing all to take part in offices, or allowing the multitude and not the law to have authority. In such a case, "the people become a monarch, from many combining into one." Properly speaking, however, such an arrangement is not really a regime, because "where the laws do not rule there is no regime."
There are several kinds of oligarchy. One type is an arrangement where there are property requirements for office, another is an arrangement where the son succeeds the father, and another is where the officials rule rather than the law.
The several types of democracy and oligarchy are here enumerated again in more detail.
The fifth sort of regime is often referred to as polity, but it has not often existed. An aristocracy properly speaking is a regime made up of those who are best on the basis of virtue. But often regimes call themselves aristocracy when officers are elected both on the basis of wealth and on the basis of virtue. There are also some types so-called polities that incline toward oligarchy.
Polity is a mixture of oligarchy and democracy. A city cannot be well-managed if it is not run aristocratically. Aristocracy's defining principle is virtue, oligarchy's is wealth, and democracy's is freedom.
There are three ways of forming a polity. One is to take elements of legislation from both democracy and oligarchy. Another is to take the mean of the democratic and oligarchic arrangements. The third option is to take selections from oligarchic and democratic law and combine them. For example, regarding offices one would have elections (an oligarchic element) but no property assessment (a democratic element). The way to decide whether a polity has mixed democracy and oligarchy well is to see if the same polity can just as easily be spoken of as a democracy or as an oligarchy. Such is the case in the Lacedaemonian (Spartan) regime.
There are three types of tyranny. One is plenipotentiary monarchy, used by the barbarians. The second is dictatorship, and the third is absolute and unchallenged kingship in which the ruler rules to his own advantage.
The virtue and vice of a city or regime can be examined much like the virtue or vice of an individualvirtue is a mean and the happy life is one in accordance with virtue. There are three parts of each city: the very wealthy, the very poor, and those in the middle. Since the mean is the best, the middling element of the city is the best part. It is best if the citizens are equal and similar persons, and this is the case with the middling elements. The best political partnership is therefore the one that depends on the middling sort and that a regime in which the middle element is proportionately larger compared to other two elements is the most capable of being well-governed. The middling element does not engage in factional conflict, and therefore cities with a larger middling element are more stable. The best legislators come from among the middling element.
The type of regime which a city has depends in large part upon the composition of its inhabitants. If the multitude of the poor is preeminent, there will be a democracy. If the well-off are preeminent, there will be an oligarchy. In any type of regime, the legislator should always aim to make the middling sort the dominant element.
There are several devices which oligarchies use to deceive the people, such as making the assemblies open but charging a fee to attend. Democracy has counterdevices, such as paying the poor to attend the assembly. A polity ought to be ruled by those possessing heavy arms. The poor will not object from not having the ability to rule provided that they are not treated contemptuously or deprived of their property. Many regimes which used to be polities are now democracies because more people shared in ruling as the size of the city increased.
There are three parts of all regimes that the lawmakers need to attend to. The first is the part which deliberates about common matter, the second is the part regarding offices, and the third is the adjudicative part. There are several ways to arrange the regime democratically such that all decide about common matterseither to have people take turns making decisions, or to have all decide at once, or to have the offices make only preliminary decisions and have the people vote on them. There are also several varieties of oligarchic decision-making, such as having only the elected authorities share in decision-making, or having a property requirement to be able to participate in decision-making.
As far as deciding about the nature and types of offices the regime should have, first it is necessary to decide what is to be considered as an office. Offices deliberative and adjudicative power regarding certain matters and command. The number and type of offices depend on the type of regime, the size of the city and the composition of the city. Another issue to be determined is the selection of officialswho selects them, from whom they are selected, and in what manner they are selected. The two most popular possibilities are to have all select from all by election or by lot.
Regarding the adjudicative part of the regime, it is necessary to determine from whom judges are selected, on what matters they decide, and how judges are selected. There are several types of courts and many different disputes which the courts handle, but the most important are the political matters, because mishandling of factional conflicts can lead to revolution.
Book IV begins with what basically amounts to a justification for political philosophy. Aristotle recognizes that the best regime really only exists in theory, but speculating about it and trying to determine its laws, structure, and underlying principles is worthwhile because it provides a model by which one can judge other regimes in see which regime is the best possible in a given situation. Political philosophy not only theorizes about which regimes are the best, but also about which laws are the most suitable for each type of regime. Aristotle believes that "laws should be enacted . . . with a view to the regimes, and not regimes with a view to laws." The fundamental fact that decides the type of regime and, by extension, the type of laws that the regime should have is the structure of authority in the regime.
Cataloging the different types of regimes is helpful in that it allows one to see what the main distinguishing factors of the various regimes are and what type of laws accompany each type of regime. The most common two types of regimes are democracy and oligarchy. In the sense that all regimes desire to be wealthy, all regimes are oligarchical, but specifically oligarchies are regimes in which the wealthy rule. Democracies are defined by the rule of the majority, assuming that the majority is relatively poor. An important point that Aristotle always comes back to when speaking about possible arrangements for regimes is that the rule of law is fundamental to a regime. Without the rule of law, there is no regime. For example, when he speaks of a type of democracy in which the assembly, not the law, has ultimate authority, he writes that this arrangement is not really a regime at all; "for where the laws do not rule there is no regime." Aristotle continues, explaining that "the law should rule in all matters, while the offices and the regime should judge in particular cases." Aristotle recognizes that the law cannot specify how it ought to be applied in each specific case. It is the job of the governing body to make those sorts of judgments, but not to rule by decree.
Aristotle believes that the best attainable regime is polity. It is interesting to note that throughout Book IV Aristotle never actually speaks of polity as such, but always qualifies the term, saying "so-called polity" or "what is termed polity." He uses the word polity in an unqualified sense when he is describing the best regime. Aristotle does the same thing when speaking of aristocracy, which, theoretically speaking is the best regime because it is the regime in which judges according to virtue and chooses its rulers on the basis of virtue. Aristotle recognizes that in its pure form such a standard is impossibly high, because it requires knowledge of what true virtue is, always as the ability to recognize true virtue in others. Therefore only "so-called" aristocracy is possible, not real aristocracy.
Polity is a mixed regimes which combines elements of democracy and oligarchy. Aristotle enumerates three possibilities for mixing regimes, but in the first twotaking elements of legislation from each and taking the mean between arrangementsthe rich are still treated as rich and the poor are still treated as poor. The third, more preferable manner of mixing regimes takes some provisions from oligarchic law and some from democratic law. This method transcends the divisions between poor and rich by having a mixture of offices chosen by lot and by election, thereby integrated the oligarchic and democratic principles into a coherent whole.
An important point which Aristotle brings out toward the end of the book of the idea of the "middling element" in society. The middling element is basically what in modern terms would be considered the middle class. Aristotle praise of the middling element is logical, in that he believes virtue to be mean between two extremes of vice. A large middle class is absolutely essential for a stable and well-run government because the middle class do not covet rule, are not envious, foster friendship because of their similarity, and can act as neutral arbitrators between the rich and the poor. Hemmed in between people above it which it dislikes and people below it which it fears, the middling element is more likely to listen to reason and to help maintain stability in the regime.