Book 1
The household and its parts
Book 1 makes three moves. First, the genetic argument: household to village to city, each stage natural, the city existing not for mere life but for the good life. Man, the creature with logos, is by nature a political animal — whoever lacks the city is either beast or god. Second, the defense of natural slavery: some are born to be governed rather than to govern; the master-slave relation is part of the household's natural structure. Third, the critique of unlimited wealth-acquisition: the art of making money has no natural limit, unlike the art of managing a household, and the confusion of the two corrupts private life before it corrupts politics. Start here — the foundations are necessary for everything that follows.
Book 2
Critiquing Plato and the legislators
Book 2 is a systematic survey and critique. Aristotle begins with the sharpest case — Plato's community of wives, children, and property in the Republic — and works outward through the Laws, through the proposals of Phaleas and Hippodamus, and then through the constitutions of Sparta, Crete, and Carthage. Each is measured against the same standard: does it actually serve the common good, and does it hold together in practice? The answer in every case is no, but the reasons differ, and each critique teaches something about what a good constitution requires. This book is where Aristotle's empirical method first shows itself against Plato's idealism.
Book 3
The citizen and the six constitutions
Book 3 is where the argument becomes a science. Aristotle begins with the definition of the citizen — not just someone who lives in a city, but someone who shares in deliberative and judicial office — and notes that the definition varies by constitution. Then he builds the taxonomy: who rules, and in whose interest? The six regime types follow, with the crucial claim that the three sound forms aim at the common good and the three corrupt forms serve the rulers' private interest. Book 3 ends with the question of who should hold sovereign power — the laws, the best man, the best few, or the many — and argues that the rule of law is better than the rule of any single person, however excellent.
Book 4
Varieties of constitution and the best for most cities
Book 4 is applied political science. Aristotle begins by noting that the political expert must understand not only what is best in the abstract but what is possible and attainable under actual conditions. He then works through the varieties of democracy (four types, from best to worst) and oligarchy (four types), argues that most people mistake the number of rulers for the essence of the constitution when the real distinction is between rule by the free and rule by the wealthy, and makes the case for polity — the mixed constitution — as the most stable and achievable form for most cities. The chapter on the middle class is the most-cited passage in the book.
Book 5
Why regimes fall and how to preserve them
Book 5 is the longest and most historically dense book in Politics. Aristotle identifies the general cause of revolution — the desire for equality when men feel unequally treated — and then works through specific causes: insolence, fear, love of superiority, contempt, disproportionate growth of one class, election intrigues, carelessness. He then examines how each type of constitution — democracy, oligarchy, aristocracy, tyranny, monarchy — characteristically fails and what preserves it. The material on how tyrants maintain power is the most unflinching political realism in the work.
Book 6
How to set up democracies and oligarchies well
Book 6 is the shortest in the Politics and the most practical. Aristotle works through how to organize the institutions of democracy — the assembly, the law courts, the magistracies — to make democratic governance as stable and just as possible. The key move is separating the principle of liberty from the extreme application of that principle: the best democracy is not the one in which the demos has the most power but the one in which the demos governs most effectively, which means agricultural democracy where the poor are too busy to attend every session. He then gives parallel advice for oligarchies before ending with the question of how to organize the military offices across all constitution types.
Book 7
The best city and the good life
Book 7 is the most philosophical in the collection. Aristotle begins by insisting that political science cannot identify the best constitution without first determining the best life — for individuals and for the city as a whole. The answer: happiness is virtuous activity, and the best city is one that enables its citizens to live and act virtuously. He then specifies the conditions: population size (large enough for self-sufficiency, small enough for citizens to know one another), territory, access to the sea, the division of the citizen body. The book is more sketch than blueprint, but the sketch reveals what Aristotle thinks politics is ultimately for.
Book 8
Education, music, and the good life
Book 8 is the most surprising and the most incomplete. Aristotle argues that education must be public — since citizens belong to the state rather than to themselves alone — and that it must aim at virtue and the proper use of leisure rather than mere utility or military fitness. He works through the four standard subjects (reading and writing, gymnastics, music, drawing) and spends most of the book on music, arguing that it is uniquely suited to forming character because it directly imitates and induces the emotions. The text breaks off in the middle of an account of the musical modes. It is the most unfinished book in an unfinished work — but the argument it makes, that the best education is liberal rather than vocational, is among the most influential in the Western tradition.