Thomas Aquinas' political philosophy, along with the broader philosophical teaching of which it is part, stands at the crossroads between the Christian gospel and the Aristotelian political doctrine that was, in Aquinas' time, newly discovered in the Western world. In fact, Aquinas' whole developed system is often understood to be simply a modification of Aristotelian philosophy in light of the Christian gospel and with special emphasis upon those questions most relevant to Christianity, such as the nature of the divine, the human soul, and morality. This generalization would explain why Aquinas seems to eschew, even neglect, the subject of politics. Unlike his medieval Jewish and Islamic counterparts, Aquinas does not have to reconcile Aristotelianism with a concrete political and legal code specified in the sacred writings of his religion. As far as he is concerned, God no longer requires people to live according to the judicial precepts of the Old Law (Summa Theologiae [hereafter ST], I-II, 104.3), and so the question of formulating a comprehensive Christian political teaching that is faithful to biblical principles loses it urgency if not its very possibility. Unlike Judaism and Islam, Christianity does not involve specific requirements for conducting civil society. In fact, most Christians before Aquinas' time (such as St. Augustine) had interpreted Jesus' assertion that we should "render unto Caesar the things that are Caesar's" (Matthew 22:21) to mean that Christianity can flourish in any political regime so long as its authorities permit believers to "render unto God the things that are God's." Although Jesus claimed to be a king, he was quick to add that his kingdom was not of this world (John 18:36), and whereas St. Paul had exhorted Christians to obey the civil authorities and even to suffer injustice willingly, he never considered it necessary to discuss the nature of political justice itself.
These observations perhaps explain why Aquinas, whose writings nearly all come in the form of extremely well organized and systematic treatises, never completed a thematic discussion of politics. His letter On Kingship (written as a favor to the king of Cyprus) comes closest to fitting the description of a political treatise, and yet this brief and unfinished work hardly presents a comprehensive treatment of political philosophy. Even his commentary on Aristotle's Politics is less than half complete, and it is debatable whether this work is even intended to express Aquinas' own political philosophy at all. This does not mean, however, that Aquinas was uninterested in political philosophy or that he simply relied on Aristotle to provide the missing political teaching that Christianity leaves out. Nor does it mean that Aquinas does not have a political teaching. Although it is not expressed in overtly political works, Aquinas' thoughts on political philosophy may be found within treatises that contain discussions of issues with far reaching political implications. In his celebrated Summa Theologiae, for instance, Aquinas engages in long discussions of law, the virtue of justice, the common good, economics, and the basis of morality. Even though not presented in the context of a comprehensive political teaching, these texts provide a crucial insight into Aquinas' understanding of politics and the place of political philosophy within his thought.
The Political Nature of Man
As we have seen, Aquinas mentions that one of the natural goods to which human beings are inclined is "to live in society." This remark presents the ideal point of departure for one of the most important teachings of Thomistic political philosophy, namely, the political nature of man. This doctrine is taken primarily from the first book of Aristotle's Politics upon which Aquinas wrote an extensive commentary (although the commentary is only completed through book 3, chapter 8 of Aristotle's Politics, Aquinas seems to have commented upon what he considered to be the Politics' theoretical core.). Following "the Philosopher" Aquinas believes that political society (civitas) emerges from the needs and aspirations of human nature itself. Thus understood, it is not an invention of human ingenuity (as in the political teachings of modern social contract theorists) nor an artificial construction designed to make up for human nature's shortcomings. It is, rather, a prompting of nature itself that sets humans apart from all other natural creatures. To be sure, political society is not simply given by nature. It is rather something to which human beings naturally aspire and which is necessary for the full perfection of their existence. The capacity for political society is not natural to man, therefore, in the same way as the five senses are natural. The naturalness of politics is more appropriately compared to the naturalness of moral virtue (Commentary on the Politics, Book 1, Lesson 1 ). Even though human beings are inclined to moral virtue, acquiring the virtues nonetheless requires both education and habituation. In the same way, even though human beings are inclined to live in political societies, such societies must still be established, built, and maintained by human industry. To be fully human is to live in political society, and Aquinas makes a great deal of Aristotle's claim that one who is separated from society so as to be completely a-political must be either sub-human or super-human, either a "beast or a god." (Aristotle's Politics, 1253a27; Cf. Aquinas' Commentary, Book 1, Lesson 1 ).
Aquinas admits, of course, that political society is not the only natural community. The family is natural in perhaps an even stronger sense and is prior to political society. The priority of the family, however, is not a priority of importance, since politics aims at a higher and nobler good than the family. It is rather a priority of development. In other words, politics surpasses all other communities in dignity while at the same time depending upon and presupposing the family. On this point Aquinas follows Aristotle's explanation of how political society develops from other lower societies including both the family and the village. The human family comes into existence from the nearly universal tendency of males and females joining together for purposes of procreation. Humans share with other animals (and even plants) a "natural appetite to leave after them another being like themselves," (Commentary on the Politics, Book 1, Lesson 1 ) and immediately see the utility if not the necessity of both parents remaining available to provide for the needs of the children and one another. As families grow in size and number there also seems to be a tendency for them to gravitate towards one another and form villages. The reasons for this are primarily utilitarian. Whereas the household suffices for providing the daily necessities of life, the village is necessary for providing non-daily commodities (Commentary on the Politics, Book 1, Lesson 1 ). What Aquinas and Aristotle seem to have in mind in describing the emergence of the village is the division of labor. Whereas humans can reproduce and survive quite easily in families, life becomes much more productive and affluent when families come together in villages, since one man can now specialize in a certain task while fulfilling his family's remaining material needs through barter and trade.
Despite the village's usefulness to man, it nevertheless leaves him incomplete. This is partly because the village is still relatively small and so the effectiveness of the division of labor remains limited. Much more useful is the conglomeration of several villages, which provides a wider variety of commodities and specializations to be shared by means of exchange (Commentary on the Politics Book 1, Lesson 1 ). This is one reason why the village is eclipsed by political society, which proves much more useful to human beings because of its greater size and much more elaborate governmental structure. There is, however, a far more important reason why political society comes into existence. In addition to yielding greater protection and economic benefits, it also enhances the moral and intellectual lives of human beings. By identifying with a political community, human beings begin to see the world in broader terms than the mere satisfaction of their bodily desires and physical needs. Whereas the residents of the village better serve their individual interests, the goal of the political community becomes the good of the whole, or the common good, which Aquinas claims (following Aristotle) is "better and more divine than the good of the individual." (Commentary on the Politics, Book 1, Lesson 1 ). The political community is thus understood as the first community (larger than the family) for which the individual makes great sacrifices, since it is not merely a larger cooperative venture for mutual economic benefit. It is, rather, the social setting in which man truly finds his highest natural fulfillment. In this sense, the political community, even though not directed to the individual good, better serves the individual by promoting a life of virtue in which human existence can be greatly ennobled. It is in this context that Aquinas argues (again following Aristotle) that although political society originally comes into being for the sake of living, it exists for the sake of "living well." (Commentary on the Politics, Book 1, Lesson 1 ).
Aquinas takes Aristotle's argument that political society transcends the village and completes human social existence to prove that the city is natural. Similar, but not identical, to this claim is Aquinas' further assertion that man is by nature a "civic and social animal." (ST, I-II, 72.4). To support this, Aquinas refers us to Aristotle's observation that human beings are the only animals possessing the ability to exercise speech. Not to be confused with mere voice (vox), speech (loquutio) involves the communication of thoughts and concepts between persons (ST, I-II, 72.4). Whereas voice is found in many different animals that communicate their immediate desires and aversions to one another (seen in the dog's bark and the lion's roar) speech includes a conscious conception of what one is saying (Commentary on the Politics, Book 1, Lecture 1 ). By means of speech, therefore, human beings may collectively deliberate on core civic matters regarding "what is useful and what is harmful," as well as "the just and the unjust." (Commentary on the Politics, Book 1, Lecture 1 ). Whereas other animals exhibit a certain social tendency (as bees instinctively work to preserve their hive), only humans are social in the sense that they cooperate through speech to pursue a common understanding of justice, virtue, and the good. Since speech is the outward expression of his inner rationality, man is political by nature for the same reason he is naturally rational.
The fact that man is a naturally political animal has far-reaching implications. In addition to being a father, a mother, a farmer, or a teacher, a human being is more importantly identified as a citizen. Achieving genuine human excellence, therefore, most always means achieving excellence as a citizen of some political society (Aquinas does mention the possibility that someone's supernatural calling may necessitate that they live outside of political society. As examples of such people, he mentions "John the Baptist and Blessed Anthony the hermit." See his Commentary on the Politics, Book 1, Lecture 1 .). To be sure, the requirements of good citizenship vary from regime to regime, but more generally conceived the good citizen is the one that places the common good above his own private good and acts accordingly. In doing so, such a person exhibits the virtue of legal justice whereby all of his actions are referred in one way or another to the common good of his particular society (ST, II-II, 58.5). Following the progression of Aristotle's discussion of citizenship, however, Aquinas recognizes a certain difficulty in assigning an unqualifiedly high value to citizenship. What sense does it make to speak of a good citizen in a bad regime? One does not need to consider the worst sorts of regimes to see the difficulty inherent in achieving good citizenship. In any regime that is less than perfect there always remains the possibility that promoting the interests of the regime and promoting the common good may not be the same. To be sure, good men are often called to stand up heroically against tyrants (ST, II-II, 42.2, ad 3), but the full potential of the good citizen will never be realized unless he lives in best of all possible regimes. In other words, only in the best regime do the good citizen and the good human being coincide (Commentary on the Politics, Book 3, Lecture 3 ). In fact, even the best regime will fall short of producing a multitude of good citizens, since no society exists where everyone is virtuous (Commentary on the Politics, Book 3, Lecture 3 ).
But what is the best regime? Following Aristotle, Aquinas argues that all regimes can be divided into six basic types, which are determined according to two criteria: how the regime is ruled and whether or not it is ruled justly (i.e., for the common good). As he explains, political rule may be exercised by the multitude, by a select few, or by one person. If the regime is ruled justly, it is called a monarchy or kingship when ruled by one single individual, an aristocracy when ruled by a few, and a polity or republic when ruled by the multitude. If, on the other hand, a regime is ruled unjustly (i.e., for the sake of the ruler(s) and not for the common weal), it is called a tyranny when ruled by one, an oligarchy when ruled by a few, and a democracy when ruled by the multitude (On Kingship, Book 1, Chapter 1; Commentary on the Politics, Book 3, Lecture 6 [393-394]). Simply Stated, the best regime is monarchy. Aquinas' argument for this is drawn from a mixture of philosophical and theological observations. Inasmuch as the goal of any ruler should be the "unity of peace," the regime is better governed by one person rather than by many. For this end is much more efficaciously secured by a single wise authority who is not burdened by having to deliberate with others who may be less wise and who may stand in the way of effective governance. As Aquinas observes in his letter On Kingship, any governing body comprised of many must always strive to act as one in order to move the regime closer to the intended goal. In this sense, therefore, the less perfect regimes tend to imitate monarchy in which unanimity of rule is realized at once and without obstruction (On Kingship, Book 1, Chapter 2). This conclusion is confirmed by the example of nature, which always "does what is best." For the many powers of the human soul are governed by a single power, i.e., reason. A hive of bees is ruled by a single bee, i.e., the queen. And most convincingly of all, the universe is governed by the single authority of God, "Maker and Ruler of all things." As art is called to imitate nature, human society is therefore best that is governed by a single authority of a eminently wise and just monarch who resembles God as much as humanly possible.
Aquinas is well aware, of course, that such a monarch is not always available in political societies, and even where he is available it is not always guaranteed that the conditions will be right to grant him the political authority he ought to wield. Even worse, there is always the danger that the monarch will be corrupted and become a tyrant. In this case the best of all regimes has the greatest tendency to become the worst. This is why, whereas monarchy is the best regime simply speaking, it is not always the best regime in a particular time and place, which is to say it is certainly not always the best possible regime. Therefore, Aquinas outlines in the Summa Theologiae a more modest proposal whereby political rule is somewhat decentralized. The regime that he recommends takes the positive dimensions of all three "good regimes." Whereas it has a monarch at its head, it is also governed by "others" possessing a certain degree of authority who may advise the monarch while curbing any tyrannical tendencies he may have. Finally, Aquinas suggests that the entire multitude of citizens should be responsible for selecting the monarch and should all be candidates for political authority themselves. Whereas the best regime simply speaking is monarchy, the best possible regime seems to be the mixed government that incorporates the positive dimensions of monarchy, aristocracy, and democracy (In the Summa Theologiae, Aquinas appears to use the name of democracy in place of Aristotle's conception of polity.). To support this conclusion, Aquinas is able to cite the Hebrew form of government established by God in the Old Testament. Whereas Moses (and his successors) ruled the Jews as a monarch, there also existed a council of seventy-two elders which provided "an element of aristocracy." Inasmuch as the rulers were selected from among the people, this sacred regime of the Bible also incorporated a certain dimension of democracy (ST, I-II, 105.1).