Below are some notes on tyranny by St. Thomas Aquinas’ famous De Regno. Here in Chapter 6, Aquinas argues that it is worse when a polyarchy (the rule of many) becomes corrupt than the rule of one (monarchy):
 When a choice is to be made between two things, from both of which danger impends, surely that one should be chosen from which the lesser evil follows. Now, lesser evil follows from the corruption monarchy (which is tyranny) than from the corruption of an aristocracy.
 Group government [polyarchy] most frequently breeds dissension. This dissension runs counter to the good of peace which is the principal social good. A tyrant, on the other hand, does not destroy this good, rather he obstructs one or the other individual interest of his subjects—unless, of course, there be an excess of tyranny and the tyrant rages against the whole community. Monarchy is therefore to be preferred to polyarchy, although either form of government might become dangerous.
 Further, that from which great dangers may follow more frequently is, it would seem, the more to be avoided. Now, considerable dangers to the multitude follow more frequently from polyarchy than from monarchy. There is a greater chance that, where there are many rulers, one of them will abandon the intention of the common good than that it will be abandoned when there is but one ruler. When any one among several rulers turns aside from the pursuit of the common good, danger of internal strife threatens the group because, when the chiefs quarrel, dissension will follow in the people. When, on the other hand, one man is in command, he more often keeps to governing for the sake of the common good. Should he not do so, it does not immediately follow that he also proceeds to the total oppression of his subjects. This, of course, would be the excess of tyranny and the worst wickedness in government, as has been shown above. The dangers, then, arising from a polyarchy are more to be guarded against than those arising from a monarchy.
 Moreover, in point of fact, a polyarchy deviates into tyranny not less but perhaps more frequently than a monarchy. When, on account of there being many rulers, dissensions arise in such a government, it often happens that the power of one preponderates and he then usurps the government of the multitude for himself. This indeed may be clearly seen from history. There has hardly ever been a polyarchy that did not end in tyranny. The best illustration of this fact is the history of the Roman Republic. It was for a long time administered by the magistrates but then animosities, dissensions and civil wars arose and it fell into the power of the most cruel tyrants. In general, if one carefully considers what has happened in the past and what is happening in the present, he will discover that more men have held tyrannical sway in lands previously ruled by many rulers than in those ruled by one.
 The strongest objection why monarchy, although it is “the best form of government”, is not agreeable to the people is that, in fact, it may deviate into tyranny. Yet tyranny is wont to occur not less but more frequently on the basis of a polyarchy than on the basis of a monarchy. It follows that it is, in any case, more expedient to live under one king than under the rule of several men.