One point that integralist Catholics have to consider from time to time is the proper form of the state. It is not uncommon to cite Thomas’s De regno in support of the proposition that monarchy is the best form of the state. Consider this passage from the De regno (c. 3):

Ad hoc enim cuiuslibet regentis ferri debet intentio, ut eius quod regendum suscepit salutem procuret. Gubernatoris enim est, navem contra maris pericula servando, illaesam perducere ad portum salutis. Bonum autem et salus consociatae multitudinis est ut eius unitas conservetur, quae dicitur pax, qua remota, socialis vitae perit utilitas, quinimmo multitudo dissentiens sibi ipsi sit onerosa. Hoc igitur est ad quod maxime rector multitudinis intendere debet, ut pacis unitatem procuret. Nec recte consiliatur, an pacem faciat in multitudine sibi subiecta, sicut medicus, an sanet infirmum sibi commissum. Nullus enim consiliari debet de fine quem intendere debet, sed de his quae sunt ad finem. Propterea apostolus commendata fidelis populi unitate: solliciti, inquit, sitis servare unitatem spiritus in vinculo pacis. Quanto igitur regimen efficacius fuerit ad unitatem pacis servandam, tanto erit utilius. Hoc enim utilius dicimus, quod magis perducit ad finem. Manifestum est autem quod unitatem magis efficere potest quod est per se unum, quam plures. Sicut efficacissima causa est calefactionis quod est per se calidum. Utilius igitur est regimen unius, quam plurium.

And in Phelan and Eschmann’s translation:

This question may be considered first from the viewpoint of the purpose of government. The aim of any ruler should be directed towards securing the welfare of that which he undertakes to rule. The duty of the pilot, for instance, is to preserve his ship amidst the perils of the sea. and to bring it unharmed to the port of safety. Now the welfare and safety of a multitude formed into a society lies in the preservation of its unity, which is called peace. If this is removed, the benefit of social life is lost and, moreover, the multitude in its disagreement becomes a burden to itself. The chief concern of the ruler of a multitude, therefore, is to procure the unity of peace. It is not even legitimate for him to deliberate whether he shall establish peace in the multitude subject to him, just as a physician does not deliberate whether he shall heal the sick man encharged to him, for no one should deliberate about an end which he is obliged to seek, but only about the means to attain that end. Wherefore the Apostle, having commended the unity of the faithful people, says: “Be ye careful to keep the unity of the spirit in the bond of peace.” Thus, the more efficacious a government is in keeping the unity of peace, the more useful it will be. For we call that more useful which leads more directly to the end. Now it is manifest that what is itself one can more efficaciously bring about unity than several—just as the most efficacious cause of heat is that which is by its nature hot. Therefore the rule of one man is more useful than the rule of many.

(Emphasis supplied.) We have discussed previously that the unity of peace is the secular common good, and that the state must be ordered to that end. One finds Aquinas’s point intuitive: it is easier for one person to order the state to the unity of peace than for a group of people, among whom dissensions will inevitably emerge. Indeed, Aquinas makes just this argument (multitudes mean dissensions) in criticizing group rule in the De regno:

Dissensio enim, quae plurimum sequitur ex regimine plurium, contrariatur bono pacis, quod est praecipuum in multitudine sociali: quod quidem bonum per tyrannidem non tollitur, sed aliqua particularium hominum bona impediuntur, nisi fuerit excessus tyrannidis quod in totam communitatem desaeviat. Magis igitur praeoptandum est unius regimen quam multorum, quamvis ex utroque sequantur pericula.

In our trusty translation:

Group government 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.

In other words, rule by a group of people is in a sense more dangerous than tyranny: a tyrant might obstruct the particular goods of this or that subject or group of subjects, but, unless he is opposed to all of his subjects, he might not wound the unity of peace as badly as group rule. We admit: this argument is somewhat opaque, but it has a certain force. Thus, the danger of tyranny—a monarchy gone rotten—is not so acute as the danger of group rule when the band breaks up, as it were.

However, in the Summa Theologiae (Ia IIae q.105 a.1 co.), Aquinas makes a very different point:

circa bonam ordinationem principum in aliqua civitate vel gente, duo sunt attendenda. Quorum unum est ut omnes aliquam partem habeant in principatu, per hoc enim conservatur pax populi, et omnes talem ordinationem amant et custodiunt, ut dicitur in II Polit. Aliud est quod attenditur secundum speciem regiminis, vel ordinationis principatuum. Cuius cum sint diversae species, ut philosophus tradit, in III Polit., praecipuae tamen sunt regnum, in quo unus principatur secundum virtutem; et aristocratia, idest potestas optimorum, in qua aliqui pauci principantur secundum virtutem. Unde optima ordinatio principum est in aliqua civitate vel regno, in qua unus praeficitur secundum virtutem qui omnibus praesit; et sub ipso sunt aliqui principantes secundum virtutem; et tamen talis principatus ad omnes pertinet, tum quia ex omnibus eligi possunt, tum quia etiam ab omnibus eliguntur. Talis enim est optima politia, bene commixta ex regno, inquantum unus praeest; et aristocratia, inquantum multi principantur secundum virtutem; et ex democratia, idest potestate populi, inquantum ex popularibus possunt eligi principes, et ad populum pertinet electio principum.

In the English Dominican translation:

Two points are to be observed concerning the right ordering of rulers in a state or nation. One is that all should take some share in the government: for this form of constitution ensures peace among the people, commends itself to all, and is most enduring, as stated in Polit. ii, 6. The other point is to be observed in respect of the kinds of government, or the different ways in which the constitutions are established. For whereas these differ in kind, as the Philosopher states (Polit. iii, 5), nevertheless the first place is held by the “kingdom,” where the power of government is vested in one; and “aristocracy,” which signifies government by the best, where the power of government is vested in a few. Accordingly, the best form of government is in a state or kingdom, where one is given the power to preside over all; while under him are others having governing powers: and yet a government of this kind is shared by all, both because all are eligible to govern, and because the rules are chosen by all. For this is the best form of polity, being partly kingdom, since there is one at the head of all; partly aristocracy, in so far as a number of persons are set in authority; partly democracy, i.e. government by the people, in so far as the rulers can be chosen from the people, and the people have the right to choose their rulers.

(Emphasis supplied.) This seems to cut strongly against the points Aquinas makes in the De regno. That is, we hear in the De regno that the risks of a monarchy (i.e., a tyranny) are less dangerous than the risks of group rule (i.e., dissensions). Now, in the Summa, we hear that everyone should take part in the government, since this better preserves peace among the people.

Moreover, Aquinas, in a reply to an objection (obj. 2 / ad 2), seems to hold that a tyranny is worse than dissensions:

Ad secundum dicendum quod regnum est optimum regimen populi, si non corrumpatur. Sed propter magnam potestatem quae regi conceditur, de facili regnum degenerat in tyrannidem, nisi sit perfecta virtus eius cui talis potestas conceditur, quia non est nisi virtuosi bene ferre bonas fortunas, ut philosophus dicit, in IV Ethic. Perfecta autem virtus in paucis invenitur […]

In translation:

A kingdom is the best form of government of the people, so long as it is not corrupt. But since the power granted to a king is so great, it easily degenerates into tyranny, unless he to whom this power is given be a very virtuous man: for it is only the virtuous man that conducts himself well in the midst of prosperity, as the Philosopher observes (Ethic. iv, 3). Now perfect virtue is to be found in few […]

And in the notes to Phelan and Eschmann’s translation to the De regno, it is observed that  Aquinas’s chapter on the avoidance of tyranny (c.7) is incomplete. They suggest, following Carlyle, that if Aquinas had completed the section, he probably would have wound up at the same place as the Summa: advancing the form of a mixed polity. And this seems at least plausible in some respects. The reply to Objection 2 in Question 105 certainly suggests that Aquinas had tyranny on his mind when considering this matter. However, this argument does not address Aquinas’s point in the Summa that a democracy—even a limited democracy—is desirable to ensure the unity of peace. Certainly he is correct when he suggests that dissensions arise among groups of people, and it is inevitable that in the group of all persons in the polity (however one wishes to qualify eligibility) there will be more dissensions. One replies to this, one suspects, by arguing that the monarchical aspects of the mixed constitution will tame the dissensions threatened by the aristocratic and democratic aspects of the constitution. Perhaps this is true.

It is an interesting question, however, and one best considered through Aquinas’s various positions on the question. It is clear, we think, that Aquinas’s thought developed, perhaps even as he wrote the De regno, but certainly by the time he wrote Question 105 of the Prima Secundae Partis, from the position that monarchy is the best constitution, if a constitution with risks, to the position that a mixed constitution is the best constitution. This development is worth considering, not least because of the reasons implied in the De regno and in Question 105. It is also worth considering because grappling with Aquinas’s thought on these matters is an essential part of reclaiming the Church’s political thought and determining how best to implement that thought today.