Having discussed in general how constitutions are overthrown, Aristotle next looks, in chapters ⅴ–ⅶ of book Ⅴ of the Politics, at democracies, oligarchies, and aristocracies in particular.
Change may come in a variety of ways: Democracies and oligarchies may abruptly change from one into the other, or may change into a tyranny. Or either variety may change to or from one in which the rulers operate within the law to one in which what the rulers say is law.
How Democracies Fall
Democracies, Aristotle says, are most easily brought to their knees by unprincipled demagogues. These may overplay their hand in seizing property from the wealthy in order to please the poor masses — either by quasi-legal means or by encouraging mob action — and thereby provoke the oligarchy to unite, strike back, and abolish democratic control.
Aristotle gives a number of examples that played out in much this way. He also notes that sometimes tyrannies have emerged from democracies when the populace has elected a strongman with military leadership experience (demagogues, Aristotle says, don’t have as much confidence in leadership or strategy, and so are more likely to try to rule by manipulating popular opinion than to try to wrest tyrannical control). A tyrant who takes bold populist action against the rich can get the support of the people in spite of being essentially anti-democratic.
Democracies can also change their character over time. They will decay if the right to vote extends over to great a portion of the population and if electioneering and pandering to voters becomes the way people come to take office.
How Oligarchies Fall
An oligarchy is vulnerable if it mistreats the populace, as it is then easier for someone with ambition to rile them up and use them to seize power, claiming to be doing so on their behalf.
Oligarchies are also subject to pressure from people who feel like they too ought to be part of the club but who are currently excluded. The more a party of outsiders grows and is denied access to power, the more incentive they have to tear everything down.
Oligarchies are also constantly under threat of internal intrigue, from factions who feel that they have been slighted and are not getting their share of power or of its fruits. This can be especially bad when the oligarchy is looting the commons and a feeding frenzy erupts where nobody wants to be left out.
Demagogues find and exploit these cracks in the constitutional order in order to pursue their own quests for power.
Oligarchies can also fall during wartime when they cede control, power, and resources “temporarily” to a military leader, who then doesn’t relinquish power or who turns the popular power of the soldiers under command against the oligarchy.
During peacetime, efforts to establish a standing military that is independent (that is, not under the control of any particular political faction) can backfire, as the military can become a faction of its own, and a powerful one at that.
Oligarchies can also fracture on mundane lines of feuding families and personal conflicts. Occasionally they can even be overthrown from within when they become too despotic and other oligarchs want to put an end to that.
Again, along the way, Aristotle alludes to a number of specific examples from history of oligarchies that have fallen in these various ways.
He notes also that sometimes an oligarchy may alter slowly and imperceptibly until its nature has changed. For instance, demographic changes or a property qualification not being properly indexed for inflation, may change the composition of the oligarchy until it approaches a democracy or polity.
How Aristocracies (and Polities) Fall
Aristocracies are like oligarchies, in being the rule of the few, but are the rule of the few virtuous, rather than the few rich, few estateholders, or few blue-bloods. This is not a particularly common form of government, so Aristotle gives fewer concrete examples in this chapter — the examples he does give largely come from Sparta, which was more of a polity than an aristocracy.
As with oligarchies, aristocracies are vulnerable to building resentment among the have-nots. Compounding this is that in an aristocracy, offices are presumably assigned in proportion to the virtue of the office-holder, so those without power are not just disempowered but also dishonored. Those who think they deserve more honor than they are getting are likely to organize and agitate.
Aristocracies are also vulnerable to demagogue-led populist insurrections that imagine redistributing the wealth to the poor masses, just as ordinary oligarchies are.
Ambitious aristocrats who find themselves with disproportionate power and who push their advantage can also threaten the stability of an aristocracy.
“But the chief cause of overthrow, both of polity and of aristocracy” says Aristotle, is a neglect of justice towards the lower classes. If the people are being economically squeezed and treated unfairly by their betters, expect trouble.
Aristotle says that in general, polities that are unbalanced towards oligarchy or towards democracy tend to continue to slide gradually in the direction of their unbalance, with occasional lurches in the opposite direction when the people on the other side feel wronged enough to do something about it.
Aristotle warns against a sort of avalanche effect that can take place once people start mucking around with the constitution in order to reform it. Once a small change is made to the constitution, a second change is easily justified, and before long the whole thing is up for grabs.
He also notes that the character of neighboring constitutions can have an effect. If you are an oligarchy surrounded by democracies, your oligarchy is more vulnerable. Or if your democracy lies in the shadow of a powerful oligarchy nearby, you may be under more than usual threat.