For Catholics interested in the social teaching of the Church, the common good is an important concept. Indeed, much hinges upon an understanding of the common good in political terms, ranging from a Thomistic understanding of law to the duties of the government. However, we have a tendency to speak of the political common good in somewhat abstract terms; that is, to imagine the common good as a hermetically sealed concept. Human law is an ordinance of reason, we say, ordered to the common good. A people may choose any of a whole host of forms of government, we observe, provided the government serves the common good. Now, these points are correct, but they are a little opaque. And the opacity does not serve broader discourse especially well. Let us put it like this: it is not good for clear thinking if a central concept in Catholic social thought is a mystery.

However, we know that the common good is not a mystery. In the De Regno (c.3), St. Thomas Aquinas tells us what, exactly, the political common good is:

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.

(Emphasis supplied.) In Phelan’s translation, as revised by Fr. Eschmann, this is rendered:

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.) Likewise, in the Summa Contra Gentiles (III, c. 146.5), Thomas observes:

Sicut medicus in sua operatione intendit sanitatem, quae consistit in ordinata concordia humorum, ita rector civitatis intendit in sua operatione pacem, quae consistit in civium ordinata concordia. Medicus autem abscindit membrum putridum bene et utiliter, si per ipsum immineat corruptio corporis. Iuste igitur et absque peccato rector civitatis homines pestiferos occidit, ne pax civitatis turbetur.

(Emphasis supplied.) In Bourke’s translation:

[J]ust as a physician looks to health as the end in his work, and health consists in the orderly concord of humors, so, too, the ruler of a state intends peace in his work, and peace consists in “the ordered concord of citizens.” Now, the physician quite properly and beneficially cuts off a diseased organ if the corruption of the body is threatened because of it. Therefore, the ruler of a state executes pestiferous men justly and sinlessly in order that the peace of the state may not be disrupted.

(Emphasis supplied.) As Pater Edmund Waldstein, O.Cist., puts it in his indispensable essay: “The primary intrinsic common good of the polity is the unity of order, peace.” And this is the end of rule, about which it is not legitimate to deliberate. He may deliberate about how to establish peace only.

Thomas’s primary example—the physician and his duty to heal his patient, much on his mind apparently in the 1260s—comes, as is often the case, from Aristotle, who in the Nicomachean Ethics (III.3, 1112b12–15) remarks:

We deliberate not about ends but about what contributes to ends. For a doctor does not deliberate about whether he shall heal, nor an orator whether he shall convince, nor a statesman about whether he shall produce law and order, nor does anyone else deliberate about his end.

(Emphasis supplied.) But Fr. Eschmann, in a note to the De Regno, observes that Thomas relies upon the Latin translation of the Nicomachean Ethics, which renders eunomia as pax. Messrs. Liddell, Scott, and Jones advise us that eunomia means “good order.” Messrs. Lewis and Short advise us that pax actually has a range of meanings, tending toward peace following some sort of conflict. At any rate, it is a question for the philologists whether or not the Latin Ethics correctly renders eunomia as pax. But it is a question for the philologists only. Thomas shows us that he means to say that, as far as he is concerned, eunomia and pax are the same thing. Consider the Summa Contra Gentiles: he teaches that peace “consistit in civium ordinata concordia.” Or the De Regno: “[b]onum autem et salus consociatae multitudinis est ut eius unitas conservetur, quae dicitur pax” (emphasis supplied). The upshot is, as we say, that peace and good order are the same thing in Thomas’s mind.

Now, there are all sorts of consequences from this correct understanding of the common good. When Aquinas, for example, tells us that human law is a dictate of practical reason ordered to the common good (ST Ia IIae q.90 a.1 co. & ad 3; Ia IIae q.90 a.2 co.; Ia IIae q.91 a.3 co.), we see that human law is really ordered to good order, unity, and peace. And when Aquinas tells us that human laws framed according to the divine and natural laws make men simply good (Ia IIae q.92 a.1 co.), we may deduce that there is an intrinsic connection between good order and virtue. Aquinas even makes this point explicit (Ia IIae q.92 a.1 ad 3). Moreover, difficult Thomistic teachings, such as his teaching on the death penalty, become clearer when it is understood that the common good is good order, peace, and unity. Subsequent teachings also snap into clearer focus, such as when the great Pius XI talks, in Quadragesimo anno, about regulating private property according to the common good. Recalling the intrinsic connection between good order and virtue, we can even progress to a deeper understanding of Thomistic scholarship, such as Charles de Koninck’s The Primacy of the Common Good Against the Personalists.

None of this is, we think, especially esoteric or even particularly hard to understand. However, it is a principle that we have seen get a little lost in the discussions about the political common good. Now that more and more people—recognizing that Enlightenment liberalism is a dead end—are exploring the perennial teaching of the Church about the rightly ordered state, which is drawn from the greater western tradition, it is essential to understand the terms of art. For example, when one says, quite reasonably, we think, that liberalism is per se corrosive of the common good, one may better understand such a statement with the correct definition of the common good in mind.