1. Supernatural Beatitude and a Philosophical Account of Temporal Happiness: Two Solutions

Two solutions to the problem raised by Strauss and Bradley have been advanced by scholars. The first is to deny that for Aquinas the only good that completely perfects human nature, satisfying its natural desire for beatitude and thus constituting its ultimate end, is the vision of the divine essence. Rather, the perfection of our nature consists in a naturally attainable good, principally the philosophical knowledge and love of God possible in the present life and secondarily acts of moral virtue. The problem of providing an account of temporal happiness―the first principle of ethics and political science―without reference to human nature's supernatural ultimate end thus does not arise precisely because natural or temporal happiness itself is the ultimate end of human nature. In other words, proponents of this solution establish the existence of a natural end that grounds a genuinely philosophical ethics and political science—something Strauss and Bradley deny is possible—by claiming that the ultimate end that perfects human nature is purely natural. The most prominent contemporary proponents of this solution are Lawrence Feingold and Steven Long, and their position was also held by many of the classic Thomistic commentators from the sixteenth through the early twentieth centuries.Footnote ⁸ The key premise of this argument, a premise formulated by Cajetan (1469–1534)Footnote ⁹ and shared explicitly or implicitly by all adherents of the first solution, is that for Aquinas natural desire cannot extend to goods that are not naturally attainable. Hence, the human person's natural desire for beatitude must be fulfilled by a purely natural good, and thus the ultimate end that perfects human nature is natural rather than supernatural.

Among contemporary scholars, the view that human nature's proper perfection and beatitude is purely natural and that consequently Aquinas's ethics and political science are philosophical is also held by Jean Porter,Footnote ¹⁰ Ernest Fortin,Footnote ¹¹ and Livio Melina,Footnote ¹² although without the extensive elaboration found in Feingold, Long, and their Scholastic antecedents. Proponents of the first solution, moreover, do not deny that according to Aquinas God has de facto elevated the human person to the beatific vision as a second final end, but their position entails that in Aquinas's understanding this good is not the fulfillment of our natural desire for beatitude and thus cannot be considered the end and perfection of human nature as such, that is, of man as man.

The problem with this interpretation is that in the key texts at issue,Footnote ¹³ Aquinas claims that the vision of the divine essence alone constitutes the complete perfection of the intellectual power. The reason for this is that a power is not perfected until it attains its object, and the object of the intellect is essence or quiddity. Short of knowing the highest essence—God's—the intellect thus does not fully attain its object and hence remains imperfect.Footnote ¹⁴ This claim has been overlooked by Feingold, Long, and those who share their interpretation, but is decisive in establishing that the supernatural beatific vision is the only end that completely perfects human nature and satisfies its natural desire for beatitude. For Aquinas, the perfection of a nature consists in the perfection of its highest power, and human nature's highest power is the intellect.Footnote ¹⁵ Hence, to assert that the vision of God's essence is the complete perfection of the intellect is to assert that it constitutes the complete perfection of human nature. In turn, since the good that completely perfects human nature is the good that fully satisfies its natural desire and constitutes its beatitude, it follows that only the vision of God satisfies man's natural desire and represents his beatitude.Footnote ¹⁶ Aquinas never asserts that the natural desire for beatitude must be satisfied by a purely natural good, as even early critics of Cajetan's view, such as Francisco de Vitoria (1483–1546), realized.Footnote ¹⁷ For Aquinas, the end of man as man is therefore supernatural, and this first solution rests on a misinterpretation of Aquinas's understanding of the finis ultimus.Footnote ¹⁸

The second solution to the Strauss-Bradley dilemma claims that ethics and political science can depend essentially on supernatural knowledge about our ultimate end and still be philosophy. This position prima facie allows one to admit, with Strauss and Bradley, that there is no purely natural end that completely perfects human nature, while still preserving the philosophical character of ethics and politics. The foremost proponent of this paradoxical solution is Jacques Maritain. In his work on what he calls “moral philosophy adequately considered,”Footnote ¹⁹ Maritain holds that moral philosophy―which includes both ethics and political science―is a subalternated science to theology, and that this does not impact its status as philosophy.Footnote ²⁰ On analogy with other subalternated sciences such as optics, which borrows on trust its principles from the higher science of geometry, taking them as hypotheses without demonstrating them, moral philosophy can assume as hypotheses premises about the supernatural end that are the object of theology. However, although ethics and political science presuppose as hypotheses the theological premises that man has a supernatural end and that virtuous activity in this life is a good worth pursuing by individuals and political communities because it is ordered to this end, ethics and political science are still formally philosophy rather than theology because they adopt a “human” or “earthly” instead of a “divine” perspective on human acts. They focus principally on the acquisition and practice of the natural virtues in this life rather than the achievement of the ultimate supernatural end through charity and the infused virtues. For Maritain, the fact that ethics and political science depend for their validity on claims about the supernatural end that can only be known through divine revelation is no obstacle to identifying these sciences as properly philosophical and essentially distinct from theology since, unlike the latter, ethics and politics primarily consider goods attainable in the present life. Among contemporary scholars, William McCormick is sympathetic to Maritain's solution.Footnote ²¹

Vernon Bourke offers another variant of the second solution.Footnote ²² He claims that for Aquinas only the vision of the divine essence could satisfy our natural desire for beatitude and that the philosopher can recognize that such a vision is beyond the capacity of unaided nature to attain. Moreover, the philosopher cannot prove that man has been given the grace necessary to attain this vision, and hence he or she cannot recognize that it is, in point of fact, the goal of human life. Nevertheless, although philosophy cannot prove that supernatural beatitude is in fact our ultimate end, it would be reasonable for the philosopher to believe that it is the ultimate goal of human life if he or she can show that, as a matter of empirically verifiable fact, the notion of a supernatural end has brought “rational order” into individuals’ lives.Footnote ²³ History, Bourke continues, proves that the concept of supernatural beatitude has indeed brought such order into individuals’ lives, specifically in the lives of Christian saints. The philosopher therefore has a plausible reason to suppose that the vision of God is the ultimate end of human life―even though he cannot prove this definitively―and he is therefore justified in determining what constitutes temporal happiness or the first principle of ethics and political science based on what is conducive to supernatural beatitude. For Bourke as for Maritain, the fact that philosophy cannot prove demonstratively that our ultimate end is supernatural is no obstacle to asserting the philosophical character of a science of human action in this life that presupposes this end as its first principle.

This solution is also inadequate. As critics of Maritain such as Bradley and Santiago Ramírez observe,Footnote ²⁴ an argument or science is not formally philosophical unless it is purely rational. If a science depends for its validity on a premise that can only be known through divine revelation, it is not philosophy but theology. It is not enough to claim with Maritain that ethics and politics can presuppose premises about our supernatural end as undemonstrated hypotheses on analogy with other subalternated sciences and still remain essentially distinct from theology simply because they focus primarily on the acquisition and practice of natural virtue in this life. The fact that an account or justification of their first principle cannot ultimately be given without relying on the data of revelation―which is not the case with other subalternated sciences such as optics―means that they are formally theological rather than philosophical sciences. Nor is it sufficient to claim with Bourke that although the ultimate presuppositions of ethics and political science can be known with certainty only through revelation, these sciences are philosophical because the philosopher has probable cause to accept the validity of a supernatural end that would ultimately ground them. For a science to be philosophical, the truth of its premises and presuppositions must be knowable with certainty to unaided natural reason. And because the historical fact that the concept of a supernatural end has brought order into the lives of individuals is not sufficient to prove the truth value of the claim that man's final end is in fact the vision of God―as Bourke himself concedes―it is not sufficient to ground a philosophical ethics and political science. Philosophy cannot rest on premises which, in the final analysis, can be known only through revelation.

These two approaches to the Strauss-Bradley dilemma thus fail to solve the problem. Other prominent scholarly treatments of the theme of a philosophical ethics and political science in Aquinas's thought have not directly answered the question of how moral science can be philosophically grounded given that for Aquinas the ultimate end of human nature is supernatural. Ralph McInerny's treatment of the philosophical character of Thomistic ethics and political science is principally a rebuttal of Gauthier's claim that in identifying God as the ultimate end Aquinas makes an irreducibly theological assertion that compromises the philosophical character of his ethics and by extension his political science.Footnote ²⁵ James Doig's study of the philosophical character of Aquinas's commentary on the Nicomachean Ethics is an argument against Harry Jaffa's claim that doctrines present in the commentary―such as the imperfection of earthly happiness and the existence of divine providence―are strictly revealed doctrines that compromise the work's philosophical character.Footnote ²⁶ It does not offer a solution to the Strauss-Bradley dilemma. Further, although Martin Rhonheimer asserts that Aquinas's ethics and, by implication, political science are philosophical despite the fact that Thomas believes only the vision of the divine essence fully perfects human nature,Footnote ²⁷ he does not offer an account of how Aquinas can both admit that human nature's beatitude and perfection is supernatural and ground an account of temporal happiness without reference to this end and hence without revelation.

Kevin Staley's treatment of the philosophical character of Aquinas's moral science likewise leaves us without a definitive solution. He argues that although for Aquinas the end of human nature is supernatural, Thomistic ethics and political science are philosophical because the temporal goods at which these sciences aim―such as friendship, political community, and philosophical contemplation―are genuine perfections of human nature.Footnote ²⁸ The fact that such goods are perfections of human nature is sufficient to establish that they should be pursued by individuals and political communities and hence to vindicate the philosophical character of Aquinas's ethics and political science. This is not, however, a solution to the Strauss-Bradley dilemma because Staley does not explain how unaided human reason can establish these temporal pursuits as perfections given the supernatural character of human nature's final end—which is the crux of the problem Strauss and Bradley raise. Other notable studies of Aquinas's understanding of imperfect beatitude have likewise left the question unanswered.Footnote ²⁹ The dilemma remains unresolved, and in the following section I offer a new solution which shows how Aquinas reconciles a supernatural end of human nature with a philosophical political and moral science.

2. Human Nature's Supernatural End and the Philosophical Character of Political Science

Although Strauss, Bradley, and the proponents of the two solutions differ in their conclusions, all agree that a coherent account of the goodness and order of human ends requires explaining this goodness and order precisely in terms of the relationship of these ends to the ultimate end that satisfies natural desire. BradleyFootnote ³⁰ and Strauss reason that because this is the case, and because the ultimate end of human nature is supernatural, no account of the lower end of temporal happiness can be given without reference to revelation about the supernatural final end―for which reason political and moral science are theology rather than philosophy. Proponents of the first solution concede to Strauss and Bradley that an account of human ends can only be given in reference to the ultimate end that satisfies human nature's desire for its perfection,Footnote ³¹ but since our temporal happiness is this end, there is no question of needing to explain the first principle of ethics and politics in terms of its relationship to a supernatural good. Proponents of the second approach agree that accounting for the goodness and order of lower ends requires reference to the ultimate end of human nature, and further agree with Strauss and Bradley that for Aquinas human nature's finis ultimus is supernatural. However, they hold that this poses no challenge to the philosophical character of ethics and political science since these sciences can depend on revelation for an account of their first principle and nonetheless remain philosophy.

This shared claim that for Aquinas establishing the goodness and order of human ends requires knowledge of their relationship to the ultimate end of human nature is mistaken. It overlooks the structure of his argument for why, even though the ultimate end of human nature is the supernatural vision of God in the afterlife, naturally acquired virtue is superior to all other natural goods and hence constitutes our temporal happiness. Contrary to the assumption of the scholars we have examined, Aquinas's writings do not establish the superiority of the activity of naturally acquired virtue to other natural goods in the present life by adducing its relationship, order, or conduciveness to the supernatural perfect good. Rather, Aquinas shows this superiority by proving that virtuous activity more fully instantiates the attributes generally ascribed to beatitude or happiness, attributes such as self-sufficiency, continuity, and leisureliness, even if virtuous living in this life does not perfectly or completely instantiate these attributes. This way of establishing the superiority of virtuous activity to other temporal goods―in effect, by proving that it is the natural good which comes closest to fulfilling the general definition of beatitude―requires no appeal to the supernatural end even though it is compatible with the assertion that such an end is the only good that fully perfects human nature. The argument does not rest on revelation, and thus a strictly rational or philosophical justification of the first principle of political science can be given.

In several texts Aquinas identifies the general attributes of beatitude and argues that, among temporal activities, the activity of acquired virtue―principally the contemplative activity of the intellectual virtue of wisdom, and secondarily the activity of moral virtueFootnote ³²―more fully instantiates these attributes than do other temporal goods even though it does not perfectly instantiate them; indeed, he suggests that only the beatific vision could completely satisfy these criteria. Six attributes of beatitude can be identified, and a consideration of Aquinas's treatment of them reveals the purely philosophical structure of his account of temporal happiness. He elaborates two of these criteria in ST I-II.3.5. First, beatitude is an activity or “operation” of man's highest power in respect of its highest object. The human person's highest power is the speculative intellect, whose highest object is the divine good. Hence, happiness must consist in contemplation of the divine good. Second, beatitude must be an operation common to human beings and higher, immaterial substances―not an operation in which purely material animals share. Only contemplation is the exclusive preserve of immaterial beings; morally virtuous action has something in common with animal action, since it is action bearing on material things.Footnote ³³ Hence, beatitude must consist in contemplative activity.

Aquinas admits that these two attributes of beatitude are perfectly fulfilled only in contemplative activity in the next life: “Therefore the last and perfect happiness, which we await in the life to come, consists entirely in contemplation.”Footnote ³⁴ We can readily infer why he thinks this. The highest way of contemplating the intellect's highest object, the divine good (God), is not contemplating God's existence and attributes but rather his essence,Footnote ³⁵ which could only occur in the afterlife.Footnote ³⁶ Moreover, the beatitude of God and the angels consists in contemplation of the divine essence, and only in such contemplation would human beatitude be perfectly common to that of immaterial beings.Footnote ³⁷ But we can also see why these attributes are, among temporal goods, most fulfilled by philosophical contemplation and hence why it is the “most perfect operation of this life.”Footnote ³⁸ Philosophical contemplation of God's existence and attributes is a form of contemplation of the highest object (the divine good) of the human person's highest power (the speculative intellect), even if it is not the highest form of contemplation of that object. Moreover, as a species of contemplative activity, it has nothing in common with animal felicity, but it does have something in common with the beatitude of God and the angels,Footnote ³⁹ who also have perfect knowledge of the divine attributes. Hence it more fully instantiates the attributes of perfect beatitude than do other temporal goods, even if it does not perfectly instantiate them.

Thomas identifies a third attribute of beatitude in ST I-II.3.2, namely, that the operation in which it consists must be one, continuous, and everlasting. This can be achieved only in the beatific vision. In the present life, contemplation cannot be continuous, and hence nor can it be one, since discontinuity implies multiplicity of operation.Footnote ⁴⁰ Nevertheless, he claims in this text that among earthly goods, philosophical contemplation is the most unitary and continuous, since the active life is busy with a multiplicity of things and as such has, as an operation, less unity and continuity than does contemplative activity.

Further attributes of beatitude which apply, preeminently among temporal goods, to philosophical contemplation are found in Aquinas's Ethics commentary. For example, beatitude or happiness is a “self-sufficient” operation, that is, an operation lacking in nothing.Footnote ⁴¹ But contemplation is especially self-sufficient since, once the necessities of life which allow for the maintenance of bodily existence are provided for, contemplative operation requires no further external goods for its performance.Footnote ⁴² By contrast, the activity of moral virtue requires external things for its exercise, such as persons to whom one can be just. Thus, acts of moral virtue are, qua acts, less self-sufficient than contemplation.Footnote ⁴³ Of course, inasmuch as certain external goods are required for the maintenance of bodily health needed to undertake philosophical contemplation, this contemplation cannot be described as absolutely lacking in nothing and self-sufficient. Only the beatific vision is a self-sufficient operation, since in it one possesses the totality of goodness such that nothing whatsoever is lacking.Footnote ⁴⁴ Nevertheless, philosophical contemplation is the most self-sufficient activity among humanly attainable operations.

A fifth attribute of beatitude is that it brings leisure―repose in the end attained―and a state of affairs in which one has nothing further to do.Footnote ⁴⁵ Only contemplative activity, however, brings such leisure and repose. The activity of moral virtues, even in their most noble form of exercise (political life), is not accompanied by leisure, since the practice of politics leaves something left to be done—specifically, contemplation.Footnote ⁴⁶ By contrast, we do not apply ourselves to contemplative activity for the sake of some other good, and accordingly it brings more leisure and repose than do other goods.Footnote ⁴⁷ Of course, contemplation of truth in this life does not bring complete repose since it is not possible for any temporal good to do so. As Aquinas writes, “contemplative activity of the intellect clearly provides for man the attributes customarily assigned to the happy person: self-sufficiency, leisureliness, and freedom from labor. And I say this insofar as it is possible for man living a mortal life in which such things cannot exist perfectly.”Footnote ⁴⁸ Presumably, the reason why complete leisureliness is impossible in this life is because, at some point, the philosopher will have to cease contemplation to provide for his or her bodily needs. At no time, therefore, does he attain perfect rest or leisure; on the contrary, only the beatific vision constitutes the complete good that leaves absolutely nothing left to seek.Footnote ⁴⁹ But contemplation in this life undoubtedly brings more repose than does the activity of moral virtue, and thus it more closely approximates the perfect leisureliness that characterizes beatitude tout court.

Finally, all admit that “delight” (delectatio) accompanies beatitude―a sixth criterion. Now, among all virtuous activities, contemplation in accordance with wisdom is most delightful. This is because the delights of wisdom are most pure since contemplation regards immaterial objects, and they are most permanent since the objects of contemplation are most unchangeable.Footnote ⁵⁰ However, philosophical contemplation in this life cannot be perfectly delightful because, so long as we are in this world, we undergo change, and perfect delight can only come from an activity that is simple and unchanging―such as God's utterly simple and unchanging activity of knowing his own essence.Footnote ⁵¹ Likewise, delight follows from an object's goodness,Footnote ⁵² but in our contemplation in this life we do not possess the perfect good. Only in the vision of God is the complete or perfect good possessed,Footnote ⁵³ and thus only this vision brings perfect delight. Yet because philosophical contemplation in this life, in contrast to other activities (including the moral virtues), does regard immaterial objects that are unchanging in themselves, it brings more delectatio than does any other temporal good.

These arguments from the Summa and Ethics commentaryFootnote ⁵⁴ all prove the same conclusion: that philosophical contemplation is the most perfect activity attainable by unaided human nature in the present life and thus the activity that bears the greatest likeness to beatitude among all purely temporal activities. Beatitude consists in an operation that is continuous, leisurely, self-sufficient, maximally delightful, shared with the immaterial beings, and related to the highest object of the human person's highest power. Among temporal, naturally attainable goods, philosophical contemplation is the most continuous, most leisurely, most self-sufficient, most delightful, most common to man and the separate substances, and most directly related to the highest object that the intellect can contemplate—even if it does not fully or perfectly instantiate these attributes. That philosophical contemplation more fully corresponds to the general attributes and definition of beatitude than do other temporal goods implies that it is more excellent, desirable, and choiceworthy than these goods. Aquinas states that the intellectual virtues are properly speaking better even than the moral virtuesFootnote ⁵⁵―to say nothing of lower goods―and that the moral virtues are means to the attainment of intellectual virtue inasmuch as the acts of the former are ordered to the acts of the latter.Footnote ⁵⁶ The contemplative person, as long as he or she lives in this world, needs the necessities of life, and thus he or she needs moral virtue so as to relate well to these temporal goods. But since these goods are clearly for the sake of enabling contemplation, so are the habits of moral virtue that order us well in respect of them.

This is not to say that for Aquinas one can choose to pursue only the acquired intellectual virtue of wisdom without cultivating the moral virtues and still attain to true temporal happiness. Since such happiness requires the perfection as far as possible of the rational part of the soul,Footnote ⁵⁷ and since the sense appetites belong to the rational part of the soul by participation inasmuch as they come under the command of reason,Footnote ⁵⁸ it follows that temporal happiness would require acquisition of the moral virtues that bring the passions fully under the control of reason in addition to the contemplative activity of wisdom that perfects the intellect. Nor does Aquinas's argument preclude him from claiming that participation in supernatural grace in the present life brings an even higher form of happiness than the activity of acquired intellectual and moral virtue. Indeed, he states that those who possess the gifts of the Holy Spirit have, in the present life, an inchoate participation in the happiness of the next, since they possess a knowledge of divine mysteries that surpasses the grasp of natural reason.Footnote ⁵⁹ The clear implication is that the incomplete supernatural beatitude of the present life is, because supernatural, an even higher form of beatitude than philosophical contemplation.

What Aquinas's argument does do, however, is establish a clear hierarchy among natural goods, with virtuous activity—principally contemplative, but secondarily moral—at its summit. In establishing the greater choiceworthiness and thus superordination of philosophical contemplation with respect to other natural goods no argumentative appeal has been made to its conduciveness to the ultimate end. The relationship of the good of philosophical contemplation to the supernatural final end has not been adduced to establish its primacy over other temporal goods. On the contrary, this supremacy has been shown solely by analyzing the general attributes of beatitude―attributes knowable to unaided reason―and assessing the degrees to which various temporal goods instantiate these attributes. This argumentative structure allows Aquinas to prove by unaided reason that the happiness or beatitude found in philosophical contemplation is superior to other temporal goods even though, in itself, it is an imperfect good that is not ultimate. Since it is thus possible for reason to give an account of temporal happiness, the first principle of politicsFootnote ⁶⁰ and ethics, these sciences are genuinely philosophical even though the ultimate end which alone satisfies natural desire is the supernatural vision of God.

3. Political Philosophy and the Subordination of Temporal to Spiritual Authority

We have seen that, for Aquinas, a rational account of temporal happiness can be given of the sort necessary for a philosophical political science that takes this happiness as its first principle, the good at which it aims. Nevertheless, De regno, a gift for the king of Cyprus exhorting him to govern justly and avoid tyranny,Footnote ⁶¹ seems to challenge the possibility of a strictly rational account of political happiness. Discussing “the origin of kingly government and the things which pertain to the office of the king,”Footnote ⁶² Aquinas states that the end of political life is virtuous living or the common good, and that the attainment of this end is the prerogative of the king in virtue of his office.Footnote ⁶³ However, this is not the human person's ultimate end; indeed, virtuous living exists for the sake of a higher end, namely, supernatural beatitude with God in the afterlife. As he writes, “through virtuous living man is further ordained to a higher end, which consists in the enjoyment of God. . . . Consequently, since society must have the same end as the individual man, it is not the ultimate end of an assembled multitude to live virtuously, but through virtuous living to attain to the possession of God.”Footnote ⁶⁴

If political society is ordained to the higher end of eternal beatitude, the question arises whether the promotion of eternal beatitude is an intrinsic element of the properly political good, such that promoting the supernatural end enters into the formal specification of the bonum civile that the king qua king is charged with procuring. If the answer is affirmative, then supernatural revelation is necessary for politics to carry out its proper task―promotion of the civic good―and a philosophical political science is impossible. Later in De regno, Aquinas appears to conclude that because virtuous living in the political community is ultimately ordered to a supernatural end, and because one who has charge over something that is ordained to a further end must ensure that the thing made is suitable to that end, the king is bound to govern in a way that makes citizens fit for the kingdom of God, taking explicit account of Christian beatitude in his political decision making:

This passage seems to imply that, for Aquinas, the political good by its very nature includes the active ordering of man to his ultimate end, such that, if a ruler does not expressly govern the citizens with a view towards preparing them for eternal life, he has failed in his duties qua ruler and has failed to uphold the specifically political good. Several scholars have interpreted De regno in this way. Citing its subordination of virtuous living to supernatural beatitude, Charles McCoy draws the conclusion that, on account of this subordination, the common good is “specified integrally by being properly ordinated to the last end.”Footnote ⁶⁶ For McCoy, the direction of citizens to eternal beatitude is thus formally included within the bonum civile, and it is therefore only insofar as politics serves as a means to the supernatural end that it realizes its proper good as politics. Benjamin Smith argues that, given De regno's subordination of moral or political virtue to the end of eternal beatitude, “theology (insofar as it is related to the ultimate end) reshapes the discourse of politics by introducing the conclusions of theology as principles in practical political deliberation.”Footnote ⁶⁷ Politics takes as its first principle the theological conclusion that man is ordered to a supernatural ultimate end and makes practical decisions about how to order the affairs of the city based on what best promotes citizens’ attainment of this end. The task of politics qua politics is therefore to serve as a means to our supernatural end. On such an interpretation of De regno, the political good by its very nature includes the express promotion of eternal beatitude, and revealed knowledge concerning the supernatural end is by implication necessary for a complete account of the bonum civile.

Nevertheless, if we read De regno in conjunction with other Thomistic texts, it becomes clear that this is not Aquinas's view.Footnote ⁶⁸ First, in a range of texts spanning the length of his career―including De regno Footnote ⁶⁹―Aquinas frequently affirms that the ruler is the “supreme authority” in political matters.Footnote ⁷⁰ To maintain, however, that the king is the supreme political authority seems incompatible with claiming that the political good includes as a constitutive element the promotion of eternal beatitude. If promotion of this end were an intrinsic element of the specifically political good, then, contrary to Aquinas's stated position, the Catholic church rather than the king would have final or supreme say in all political affairs, since all political affairs would be reducible to mere means to the supernatural beatitude over which the church has ultimate custody. These texts suggest a formal distinction between the political and supernatural goods, between kingly and ecclesiastical office, that does not subordinate the former to the latter in all affairs, as would be the case if promoting eternal beatitude were an essential part of the political good. Further, Aquinas clearly distinguishes the “earthly city” which aims at the happiness brought about by naturally acquired virtue from the “heavenly society of Jerusalem”—eternal beatitude—of which man is made a citizen not by acquired virtue but only by supernaturally infused virtue.Footnote ⁷¹ The implication is that the two cities and the authorities which govern them have formally distinct goods and that promoting the beatitude of the heavenly city does not enter into the task of the earthly city qua earthly city, since progress towards eternal beatitude requires supernatural virtues that politics—which belongs to the natural order—could never produce.

The text in which the formal distinction between spiritual and temporal authority is most fully articulated, and from which emerges most clearly the specification of the political good as an independent good that does not include express promotion of the finis ultimus, is found in the commentary on Sentences II. Discussing the relationship between spiritual and temporal power, Aquinas explains that there are two ways in which a higher and a lower power are related. In one way, the lower power is derived completely from the higher, as the authority of a lower government official is derived completely from that of the emperor.Footnote ⁷² The higher power is to be obeyed before the lower in all things. In the second way, however, there is only a qualified subjection of the lower power to the higher:

Aquinas holds that the kingly office is specified by the civic good, whereas the priestly office is specified by “the salvation of souls”―eternal beatitude. By a divine ordinance, the king is subject to the priest in matters bearing directly on the attainment of this supernatural end,Footnote ⁷⁴ while in matters bearing solely on the civic good, the priest is subject to the king. The implication is that whenever the king takes measures directly aimed at promoting the supernatural end, as distinguished from those which only bear on the political end, he is acting to promote an end that formally belongs not to him but rather to the priest. In matters bearing on eternal beatitude, the king acts only as the subject of the priest, on the priest's authority and thus as his instrument in the attainment of a good that pertains to the priestly office alone—a good that does not come under the charge of the king qua king or the bonum civile the king is tasked with promoting.

Further, according to the text, the obligation of the ruler to promote eternal beatitude as the subject and instrument of the priest arises not from the nature of political office itself but rather from a special divine ordinance establishing the relation and order between spiritual and temporal power―an ordinance which, as we will see, Aquinas identifies elsewhere with the New Law. This ordinance is entirely extrinsic and accidental to the obligations that pertain to the king qua a ruler tasked with procuring the common good. Of course, the king in virtue of his duty to promote the bonum politicum is bound to prescribe acts of natural virtue and prohibit acts of vice, and insofar as this incidentally aids in the attainment of supernatural beatitude by removing obstacles to it, the king can be said to promote the supernatural end indirectly. But he exercises independent authority in these matters only insofar as they are directed towards the realization of the civic good. Any benefit that accrues to citizens in respect of the supernatural good is strictly incidental to the promotion of the political good that is the king's proper task, and if an act does not bear on the attainment of the bonum civile, then the king has no right to make legislation about it. Even when an action does bear on the bonum civile, if it also bears on the supernatural end—as in the case of Christian marriage—the king can regulate it only insofar as the spiritual authority allows him to do so, and only in view of the temporal good.Footnote ⁷⁵

Some examples of political promotion of the supernatural end that Aquinas adduces illustrate the strictly instrumental role that political authority plays in promoting eternal beatitude. He states that it belongs to the church to determine whether the religious rites of non-Christians are to be tolerated or forcibly repressed for the sake of advancing the supernatural end.Footnote ⁷⁶ He makes the same observation concerning the suppression of heresy, arguing that the church decides whether to condemn heretics and hand them over to the temporal authority for capital punishment: “If [the heretic] is yet stubborn, the Church, no longer hoping for his conversion, looks to the salvation of others, by excommunicating him and separating him from the Church, and furthermore delivers him to the secular tribunal to be exterminated thereby from the world by death.”Footnote ⁷⁷ Similarly, in order to force schismatics to return to the church for the sake of their salvation, the church “employs the compulsion of the secular arm [i.e., the state]” for this purpose.Footnote ⁷⁸

In these Summa texts, Aquinas envisages the temporal power undertaking the actions described not on its own authority but only at the behest of the church, which uses or instrumentalizes state power for specific actions directly intended to promote the attainment of supernatural beatitude.Footnote ⁷⁹ His assertion in each passage that the church decides whether and how the state is to punish sins against the faith that undermine the attainment of our supernatural end suggests that it is the prerogative of the church, not the state, to make such decisions, and the logical explanation for the church's exclusive right to take such actions is that they bear on an end that the spiritual authority alone is tasked with promoting.

Key passages in De regno articulate the same understanding of the relationship of temporal to spiritual authority found in other works, namely, that the authority of the ruler qua ruler extends solely to actions bearing on the human person's temporal end; that the king is bound to promote supernatural beatitude only as directed by the ecclesiastical power and hence as its instrument; and that this obligation arises not from the political good itself but rather from an extrinsic divine ordinance or law. In the same text in which Aquinas writes that the king, having custody over a lower end, should make laws that render men apt for the higher end of eternal beatitude, he adds that these laws are learned from the teaching of the priests and hence that it is only as taught or instructed by the priest that the king should promote the citizens’ eternal beatitude.Footnote ⁸⁰ This qualification―which has been overlooked in scholarship on the passage―suggests that it is only under the direction of priests that kings make ordinances that are expressly intended to promote heavenly beatitude, and, by implication, that kings make such ordinances not in service of their own proper end but strictly as appendages of the ecclesiastical power in the attainment of its own, formally distinct end.

Moreover, in De regno 2.3, Aquinas writes that “all the kings of the Christian people are to be subject [to the pope] as to our Lord Jesus Christ Himself” inasmuch as they are bound to obey papal commands in matters pertaining to the supernatural end.Footnote ⁸¹ Of note is Aquinas's qualification that only the rulers of Christian peoples are bound to be subject to priests (principally the pope) in promoting eternal beatitude, not the rulers of all peoples. This suggests that the obligation to promote the supernatural end arises not from the nature of political office itself―since otherwise all political rulers would be obliged to obey the pope―but only from the fact that the ruler is Christian. Aquinas confirms in the subsequent paragraph that the obligation to promote the supernatural end arises from an ordinance extrinsic to the political good and hence is not part of the bonum civile as such. Contrasting the obligations of kings in relation to priests before and after the coming of Christ, he writes:

The text affirms that the obligation of kings to be subject to priests arises only under the “law of Christ” or the New Law, a law which is not binding for all times or on all persons but only on Christians.Footnote ⁸³ The king qua king is not obliged to order the body politic under the direction of the priests with the explicit aim of making it “suitable for the attainment of heavenly happiness”―except insofar as his promotion of the civic good of virtuous living incidentally promotes this beatitude by removing obstacles to it―but the king qua Christian is under such an obligation because of his acceptance of the New Law and the additional obligations arising from it.Footnote ⁸⁴ Specifically, he is under an obligation to do what the ecclesiastical power orders him to do in those matters which bear directly on the attainment of the ultimate end over which the church has sole charge. Thus, when Aquinas urges the Cypriot monarch in De regno to “command those things which lead to the happiness of heaven and, as far as possible, forbid the contrary,” and to make the multitude “suitable for heavenly happiness”―a text which, as we have seen, suggests prima facie that promoting supernatural beatitude is a constitutive element of the political good―Aquinas's meaning is that his addressee should carry out his specifically Christian duties as a Christian king to follow ecclesiastical directives in matters bearing on the eternal salvation of the citizens. His meaning is not that qua king the Cypriot prince's role is to promote the human person's supernatural end, but only that as a Christian ruler he is obliged to carry out through legislation the church's directives in matters directly pertaining to the ultimate end, an end over which the church has exclusive custody.

In a work that is a hortatory letter rather than a scientific treatise, it is not surprising that, in lines exhorting the prince to govern well precisely as a Christian king, Aquinas would not parse the exhortation into those obligations his addressee is bound to carry out qua king as distinguished from those which he is bound to carry out qua a Christian under the New Law―even though, as we have seen, the distinction is implied in the passages urging the king to legislate with an eye towards heavenly beatitude as instructed by the priest. Indeed, as Marc Guerra has observed, citing the example of the foundations of justice, De regno often presupposes a range of concepts that are developed fully only in Aquinas's theoretical works.Footnote ⁸⁵ The doctrine that a state's political promotion of supernatural beatitude is strictly an instrument used by the church in the service of the church's own end, an end entirely separate from the state's, is thus the same in De regno as in the other Thomistic texts we have considered, as is its teaching that the ruler's obligation to advance the cause of heavenly beatitude arises not from the nature of the political good itself but rather from a special divine ordinance, namely, the New Law or “law of Christ.” Explicit ordering of political life to the finis ultimus is thus not a constitutive element of the bonum civile, and when Aquinas affirms that the political good of virtuous living is ordained to eternal beatitude as to a further end, he means only that it is ordained to such an end by an extrinsic divine law―not by its very nature. The bonum politicum remains a purely natural good. This analysis does not entail, of course, that the political good is strictly secular. On the contrary, for Aquinas religion understood as rendering thanksgiving to God qua creator and providential governor of the universe is a natural virtue that is a part of justice and thus the common good, for which reason even non-Christian kings are bound to public acts of monotheistic worship.Footnote ⁸⁶ But the analysis does mean that the bonum civile is naturally attainable and knowable by human reason without the aid of divine revelation.