Aristotle seems to think of the causes of the overthrow of oligarchies as falling broadly into two classes, internal and external. Yet his exposition makes it clear that the distinction is not particularly neat: in the third paragraph, for instance, demagogues within an oligarchy rely on the support of the people, whom they encourage to exert external pressure. Nevertheless, Aristotle evidently thinks of this as an ‘internal’ cause, in the sense that it is rivalry among the oligarchs that causes them to seek among the people a wider base of support. In practice, as he recognizes, internal and external causes react on each other in a variety of complex ways. His presentation is slightly confused by his tendency to ‘exalt the occasions of constitutional change into causes’ (Newman IV, 345), as for example in the case of the purely personal animosities in paragraph six, which must have been merely the accidental trigger for the expression of more widespread discontents (cf. V iv). But rough-and-ready as some of his analysis may be, its fullness of detail is impressive, and serves to remind us once more that Greek constitutional forms were not monolithic but exhibited tremendous variety of origin, rise and fall. Indeed, Aristotle concludes the chapter by remarking that oligarchies and democracies change not only into each other but into different species of the same form.
1305a37 Turning now to changes in oligarchies, we find that the two chief ways in which they occur are the most conspicuous. One is when the oligarchs wrong the multitude, in which case any champion is good enough, particularly when the multitude happens to be led by someone from the oligarchy itself, like Lygdamis at Naxos who afterwards actually ruled as tyrant there.
1305b1 There are also various ways in which faction originating from other people may cause an oligarchy to fall. Sometimes the initiative comes from the rich themselves, from those of them who are not included among the officials, when the number of those enjoying such honours is very small. This has been known to occur in Massalia, in Istros, in Heraclea, and in other states. Those who had no share in the offices kept on agitating until first elder brothers and then the younger were admitted to a share. For in some places it is not permitted that father and son should hold office simultaneously, in others not elder and younger brothers. At Massalia, the oligarchy changed into something rather like a polity, but at Istros it ended by becoming a democracy, and at Heraclea the few were increased to 600. At Cnidos too change was due to strife among the notables themselves, owing to the fact that the numbers participating were small, and, as has been mentioned, if a father did so, a son might not, and of a number of brothers only the eldest. The people intervened in the faction, chose a champion from among the notables, and carried out a successful coup (faction makes an easy prey). At Erythrae too in early times, under the oligarchy of the Basilidae, in spite of the excellent way in which those included in the constitution were discharging their responsibilities, the people, chafing at rule by a few, changed the constitution.
1305b22 The other type of internal change in oligarchies arises directly out of the oligarchs’ own rivalry, which turns them into demagogues. Now there are two kinds of demagogy, one which functions within the ranks of the few themselves (for a demagogue can arise even when there are very few indeed), the other when members of an oligarchy act as demagogues to the common crowd. Examples of the first are the demagogy which made Charicles’ men powerful during the time of the Thirty1 at Athens, likewise that of Phrynichus’ associates during the time of the Four Hundred.2 Of the second, a good example was Larissa, where the Citizen-Guardians played the demagogue to the common crowd because they were elected by them. And this second kind is apt to occur in any oligarchy where the officials are not elected by the persons from whom they are drawn, but offices are dependent on a high property-qualification or on membership of a political club, and the electors are the hoplites or the people, as happened at Abydos; also where the courts are not manned by the citizen-body,3 for demagogy to influence verdicts4 may lead to change in constitution, as happened at Heraclea on the Euxine; and further whenever one set tries to reduce the size of the oligarchy still more, for then the seekers of equality5 are forced to summon the people to their aid.
1305b39 Then too there are oligarchies where change is due to the spending of private resources on extravagant living. For persons of this type too seek to make innovations, either aiming at tyranny themselves or putting up some other person. Thus at Syracuse it was Hipparinus who did this to Dionysius,6 and at Amphipolis the additional Chalcidic settlers were brought by a man called Cleo Imus, who on their arrival formed them into a faction against the well-to-do; and at Aegina the person who had carried through the negotiations with Chares tried to change the constitution for some similar reason.7 Sometimes they do not wait, but try to make changes immediately; sometimes they secretly help themselves to public funds, and then either they themselves form factions against each other, or else others form factions against them, in order to combat the theft, as happened at Apollonia on the Euxine Sea.
1306a9 An oligarchy which is of one mind with itself is not easily destroyed from within; a good example is the constitution at Pharsalus, where a few men continue to have sovereign authority over many simply because they treat each other properly. Oligarchies are also destroyed when an attempt is made to set up one oligarchy within another. This occurs whenever, with a total citizen-body that is not large, not all the few share in the highest offices. It once happened in Elis, where the constitution was in few hands, and very few persons were ever added to the Elders, because the existing members held office for life and the total was fixed at ninety; moreover the method of election favoured the group in power,8 and was like that of the Elders at Sparta.
1306a19 Change away from oligarchies takes place both in war and in peace – in war, because they are obliged, owing to their mistrust of the people, to employ mercenary soldiers; for the man to whom they have committed the command of these troops often becomes tyrant, as Timophanes9 did at Corinth; and if there are several of them, they set up a power-group of their own. Sometimes, just for fear of these results, being obliged to employ the people in defence, they give the multitude a share in the constitution. In peace, on the other hand, owing to their mutual mistrust, they commit the country’s defence to mercenary soldiers with a neutral commander, who sometimes gets sovereign power over both parties, as happened at Larissa during the rule of the Aleuadae who were associates of Simus; so too in the case of Iphiades at Abydos, when he led one of the clubs of that time.
1306a31 Factions also occur because one set among the oligarchs themselves is thrown out by another, and because factions arise out of lawsuits or dealings connected with a marriage. Some factions of matrimonial origin have been mentioned already;10 to these may be added the knights’ oligarchy at Eretria, which was brought low by Diagoras, who had suffered an injustice connected with a marriage. The factions at Heraclea and at Thebes were due to a law-court verdict: the court at Heraclea inflicted punishment on Eurytion on a charge of adultery – justly, but in a spirit of faction; while at Thebes the court found against Archias, and their enemies were so hot against them that the men were tied in the pillory in the market-place. Many oligarchies have fallen owing to their excessively despotic11 rule, brought low by some of their own members who disapproved: the oligarchy at Cnidos, for example, and that at Chios.
1306b6 A combination of circumstances sometimes leads to change both in what we call polities and in those oligarchies in which entry to the council, the law-courts and other offices is open only to those of a certain property-qualification. For often the qualification, when it is first fixed, is well suited to its purpose at the time: in an oligarchy it ensures that few participate in the constitution, in the polity all the middle people. But prosperity ensues, thanks to a period of peace or some other good fortune, and it comes about that the same amounts of property are worth many times as much as before in the scale of assessment, and so everyone comes to share in everything, the change occurring either quickly or gradually and little by little, without being realized.
1306b16 Such then are the causes of change and faction in oligarchies. We may add this general remark: both oligarchies and democracies sometimes develop not into their opposites but into constitutions still of the same class. For example a democracy or an oligarchy that is bound by laws may change into a democracy or an oligarchy with sovereign power, or vice versa.12