Roughly speaking, there are six kinds of constitution, three just and three unjust. A constitution is just when it benefits everyone in the city and unjust when it benefits only those in power. When a single person rules, a constitution is a monarchy if the ruler is good and a tyranny if the ruler is bad. When a small elite rules, a constitution is an aristocracy if the rulers are good and an oligarchy if the rulers are bad. When the masses rule, a constitution is a polity if they rule well and a democracy if they rule badly. Aristotle acknowledges that giving full sovereignty to either the governing body or the laws might make room for abuses of power and suggests that a polity is probably least susceptible to corruption, especially when the laws are given higher authority than the governing body. He proposes a principle of distributive justice, saying that benefits should be conferred upon different citizens differently, depending on the contribution they make to the well-being of the state.
In Books IV to VI, Aristotle turns from his theoretical speculations to a practical examination of political institutions as they exist in the Greek world. He observes that the needs of city-states vary greatly depending on their wealth, population, class distribution, and so on. He examines the different varieties of states and constitutions and makes a number of general recommendations. The greatest tension in any state is the mutual resentment between the rich and the poor. Consequently, a strong middle class keeps a state in balance and guards against corruption and oppression. The three branches of civic government are the deliberative, which makes the major political decisions of the state; the executive, which runs the day-to-day business of the state; and the judicial, which oversees the legal affairs of the state. Though it is not necessary to give everyone equal access to public office, it is never wise to exclude entirely any group from power. Constitutions are usually changed by a large, dissatisfied faction that rises up against the people in power. To preserve a constitution, Aristotle recommends moderation, education, and inclusiveness. The interests of the rich minority and poor majority can be balanced by allowing both factions a roughly equal amount of power. In such an arrangement, each individual rich person would have more political power than each individual poor person, but the poor and the rich as groups would be balanced against one another.
Books VII and VIII return to the question of what the ideal state would be like. The good life consists primarily in rational contemplation, so even though political action is admirable and necessary, it is only a means to the end of securing the ultimate happiness of rational contemplation. An ideal city-state should be arranged to maximize the happiness of its citizens. Such a city would be large enough for self-sufficiency but small enough to ensure fellow feeling. It should be located by the water to allow for easy sea commerce. Young citizens serve in the military, middle-aged citizens govern, and older citizens take care of religious affairs while noncitizen laborers take care of farming and crafts. Education is important to ensuring the well-being of the city, and Aristotle prefers a public program of education to private tutoring. He recommends that care be taken to breed the right habits in children from the time they are in the womb and that when they mature they learn to hone their reason. His recommended curriculum consists of reading and writing, physical education, music, and drawing. This education will help citizens make the most of both work and play, as well as the leisure time in which to pursue the good life.
