In most of the rest of book Ⅵ of the Politics, Aristotle returns to a subject that also concerned him in book Ⅴ: how to preserve a constitution against the forces of decay.
One source of instability in a democracy is the temptation for a popular leader to curry favor with the populace by using the legal system to seize money from the rich (to redistribute or for public works). Aristotle recommends as one possible remedy for this that a law be passed saying that any penalties fixed by the courts should be spent only for religious purposes and should not be remitted to the treasury.
In order to function as a real democracy, all the people of the state have to come together to decide on things together. This is among other things a logistical problem. It’s also a hardship for the average joe to take the day off, trek to town, and stand around listening to people having political arguments all day. Some democracies tried to solve this problem by paying people to attend the assembly, so it doesn’t just become a club of eccentric wonks and the idle rich. But where do you get the money to pay everyone? From “taxation and confiscation and depraved courts” typically, Aristotle says, and notes this has been the downfall of many democracies. He recommends restricting the amount of time devoted to government as much as possible so as to reduce this cost.
Should there be a surplus in the treasury, a democratic leader will be tempted to give the money away to the poor in a big popular bonanza. Aristotle thinks this is a bad idea. For one thing, the poor will just get used to expecting these sorts of payouts, and that’s no good. A better plan would be to try to improve general prosperity. That might include some sort of welfare program for the poor, but one that is more targeted and deliberate than just a big cash giveaway.
The healthiest sort of democracy, says Aristotle, has some oligarchical elements mixed in.
And similarly, an oligarchy gains vigor and durability the further it travels away from absolute oligarchy and towards a hybrid oligarchy/democracy mean. As an oligarchy becomes more absolute it becomes more brittle and less able to withstand stress. You don’t have to bring all of the commoners in on your government, but try to come up with at least some limited ways for some of them to participate.
Oligarchies are most likely to thrive when (for geographic or geopolitical reasons) an expensive military branch is necessary. For instance, if your polis relies on cavalry, your military will be dominated by those who can afford to keep horses, which will reinforce oligarchical norms. If your military is dominated by the more democratic light infantry or navy, however, an oligarchy will have a harder time justifying itself and will find the military has become a democratic power center that may pose a challenge to it. In such a case, consider enlisting the sons of the oligarchs in your military so that it does not become a hotbed of democratic sentiment.
If you require oligarchical office holders to fund public activities, establish public works, throw banquets, and the like, the common people will be more satisfied with a constitution that otherwise neglects them. These things also become a sort of public relations campaign for the oligarchy. Alas, “nowadays” oligarchs are too short-sighted, and tend to rob the commons rather than adorn it.