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The Libertarian Aquinas

Jonathan McIntosh (Ph.D., University of Dallas) is a Fellow of Humanities at New Saint Andrews College in Moscow, Idaho, where he teaches on the history of western political and economic thought, philosophical theology, natural law ethics, Aquinas, Anselm, and J.R.R. Tolkien. He is the author of The Flame Imperishable: Tolkien, St. Thomas, and the Metaphysics of Faërie, and blogs at The Natural Law Libertarian and The Flame Imperishable

Aquinas and Libertarianism

St. Thomas Aquinas (1225-1274) is, without question, one of history’s greatest thinkers. Preeminent among the “doctors” of the Roman Catholic Church, he was a major influence on many early Protestant thinkers as well, and today his writings continue to be studied and referenced by a diverse range of readers, including Christians and non-Christians alike. In addition to notable contributions in theology, metaphysics, and ethics, Aquinas has also earned himself a permanent place in the annals of the history of political philosophy. His most important political writing, the so-called “Treatise on Law” from his celebrated Summa Theologiae, has for centuries been admired for its lucid and cogent systematization of biblical, Greek, Roman, patristic, and ecclesiastical (“Canon”) sources of law. These provided Aquinas with some of the more important stonework from which he, like one of the architects of the many Gothic cathedrals being built throughout Europe in his day, compiled into a single, impressive intellectual edifice.

Yet Aquinas was also no libertarian. Far from it, he viewed politics not, in libertarian fashion, as a science of the moral use of coercion in preventing or punishing acts of aggression, but under the influence of Aristotle, as the science of the highest, most “perfect” community ordered to the highest human end of happiness or well-being. In contrast with St. Augustine (AD 354-433), who taught that political subordination of one man to another was a species of slavery permitted by God only after the Fall as a consequence of and check on human sin (City of God 19.15), Aquinas was led by his studies in Aristotle to view man as a political animal by nature who, even before the Fall, in his original “state of innocence,” was in need of a (non-coercive) form of political authority to coordinate the activities of the individual members of the community towards the “common good” (Summa Theologiae I.96.3-4). Even now, after the Fall, a key component of the political common good for Aquinas is the responsibility rulers or governments have to oversee and ensure the moral formation of their citizens and the inculcation of virtue. Given this end, unsurprisingly, there is hardly any aspect of human social order that Aquinas does not see, at least in principle, as falling under the purview of the state. From the well-being of the family, to the suppression of religious heterodoxy, to the regulation of many areas of the economy, including fixing the exchange value of money, regulating foreign and domestic trade, and the production of those goods or services deemed necessary for the community, all of these are things that governments have both the right and the duty to oversee for the collective good. Even private property, which Aquinas acknowledges to be a practical necessity, is viewed not as a pre-political, natural right which law and government merely serve to protect, but as a post-fall institution that is created by political communities as a matter of social convention and convenience.

These anti-libertarian sentiments notwithstanding, there are yet many other respects in which Aquinas’s political thought is not only consistent with libertarianism, but arguably provide the latter with an ideal and even necessary, moral and metaphysical framework. To begin with his theology and metaphysics, for Aquinas, the center and source of all reality is a God who is reason and freedom himself, and who has made human beings after his own image and likeness. By virtue of their God-given power of free will, human beings are unique among God’s creatures for their ability to be the initiators and “masters” of their own actions (ST I-II.1.1), such that in order for any action to be truly human, it must have the individual’s own will and reason as its immediate and proximate source and explanation. For Aquinas, in a word, it belongs to the nature of human beings to be persuaded rather than forced into action. Consistent with this, Aquinas acutely defines coercion as any act of violence in which one is moved to act in a way contrary to the inclination of one’s own will (ST I.82.1). And although he views individuals as parts of the communal wholes to which they belong, he is equally emphatic that, as individuals, they are also always more than mere parts of their community who retain a metaphysical identity and significance that is irreducible to their purely political standing (SCG 3.113).

In his “Treatise on Law,” Aquinas’s overall purpose is to show the necessary role law plays in directing man to his natural, and ultimately supernatural, ends. Yet Aquinas also stresses throughout the inherent limits of law. He roots the nature of law, not, in legal positivist fashion, in mere political power and procedure, but in the objective realities of man’s rational and moral nature (ST I-II.90.1, 93.3, 95.2), and bases government’s own authority to make law on the authority and consent of the people (ST I-II.90.3). Although he does not include coercion in his formal definition of law, he does recognize that coercion is nevertheless part of the very concept of law (ST I-II.96.5), and it is when meditating on law’s coercive nature, significantly, that Aquinas has his most libertarian moments. For example, despite his idealization of law as a means for morally forming members of society, he also says that the law primarily exists to restrain those “depraved” individuals who have not received sufficient moral training by other, more preferable means (ST I-II.95.1), and for which reason law ought not attempt to punish all vices, but only the “graver” kind, such as murder and theft, that involve acts of outright aggression against others (ST I-II.96.2). While God’s eternal law is over all things, rewarding actions that are good and punishing those that are evil, it is also what permits human beings to use their freedom to deviate from the eternal law in ways that no human law is authorized to prohibit (ST I-II.91.4, 93.3), and only the divine law of grace, revealed in the New Testament, can regulate the human heart, whereas human law is limited judging external actions (ST I-II.91.5). Because all man-made law must legislate strictly within the bounds determined for it by the natural law (ST I-II.95.2), those so-called “laws” that deviate from the natural law are no true laws at all and so do not bind the conscience and may be resisted (ST I-II.96.4). And although Aquinas is never specific as to what the natural-law boundaries for human law are and allows each political society to make its own body of “civil laws” (ius civile) that are specific to it its unique situation, he also recognizes the existence of a universal “law of nations” (ius gentium) that he believes is logically deducible from the natural law and that, in libertarian fashion, largely concerns the protection of individuals from actions of violence, theft, and fraud (ST I-II.95.4).

These are only a handful of the many dimensions of Aquinas’s political philosophy of interest, both by way of similarity and difference, to the Christian libertarian. In the series of posts to follow, accordingly, we will undertake a survey of Aquinas’s “Treatise on Law,” aiming to pinpoint precisely those areas of disagreement between the Thomistic and libertarian approaches to law, but also those areas of either real or at least possible agreement. In doing so, my hope is to sketch at least the outlines of a distinctly Thomistic, natural law libertarianism, one that coherently combines Aquinas’s account of law’s place within the social and moral dimension of human nature, with libertarianism’s more considered and consistent ethic of law’s inherently coercive nature.

Definition of Law

In the opening chapter, or “question,” of his “Treatise on Law,” Aquinas sets out to define what law is by asking four fundamental questions: (1) what kind of thing is law? (2) what is the purpose or end-goal of law? (3) who can make and impose law? and (4) must law be promulgated? His answers to each of these questions comprise his famous, four-part definition of law: law is “an ordinance of reason, for the common good, made by one with care of the community, and promulgated.” Although Aquinas intends his definition of law to apply to far more than merely human law, including divine and natural law, in this post we will be considering each part of his definition of law specifically as it applies to the civil realm, along with what a libertarian response might be.

What is law? Aquinas argues that law is an “ordinance of reason,” meaning that it is something that reason itself orders, commands, or directs human beings to do (ST I-II.90.1). The idea here is that law regulates human action, but normally, in everyday life, the way in which human beings regulate their actions is by means of their reason. If law, therefore, is to accord and not conflict with our human nature as rational beings, then Aquinas’s point is that law must belong to that order of things that reason itself directs us to do.

While the libertarian might want to clarify precisely which commands of reason are to be made a matter of law (principally those prohibiting acts of aggression), the fact that law should be an ordinance of reason he would scarcely wish to disagree with. In contrast, for example, with the legal positivism dominating much jurisprudence today, according to which law is whatever rules have been established and enforced by those in political authority, for Aquinas, law is never merely law because of some government’s or ruler’s say-so, but is authoritative only so far as it may be seen to participate in an objective, rational order by which human actions are directed to recognizably human ends. The authority of law is, and must be, the authority of reason.

Where Aquinas and the libertarian begin to part ways is in his answer to his second question about law: what is the purpose of law (ST I-II.90.2)? Because all human action is directed by reason to man’s ultimate end of human happiness or flourishing, and law belongs to reason as a means of directing human action, Aquinas concludes from this that the end of law is not any individual’s private or particular good, but the common good of a community’s shared or “universal happiness.”

Taken by themselves, Aquinas’s view that all human action and hence law are ultimately ordered to happiness, and that the end of law is the common good, are not at all inconsistent with libertarianism. For the libertarian, after all, the end of law is the protection of individuals from acts of aggression, an end that is clearly a common good in Aquinas’s sense of the term, and one that he would certainly include as at least a part of the common good brought about by law. Where the libertarian would disagree, rather, is with Aquinas’s claim that the common good aimed at directly by law, giving it its immediate, proper, or distinguishing end, is specifically the community’s shared happiness or well-being. Why should this be assumed to be law’s defining goal? Significantly, Aquinas utterly fails to shows that this is the case, for from the premise that all human actions and law are ultimately ordered to the end of human happiness, it does not at all follow that law is, as he puts it, “chiefly and mainly” concerned with happiness. On the question of the defining purpose of law, then, the place where the libertarian breaks with Aquinas is precisely where Aquinas’s own argument breaks from reason.

Aquinas’s third question for law asks who is in a position to make law, with Aquinas’s answer being that only the whole community, or else its appointed representative, can make law (ST I-II.90.3). Here Aquinas implies something the libertarian would also affirm, namely that the authority to make law lies foundationally with the people, and that the only authority governments or rulers have to make law is an authority conferred upon them by the people. Unfortunately, what Aquinas doesn’t address is where the people themselves get their authority to make coercive law. For the libertarian, a people’s right to make coercive law is simply a consequence of its individual members’ right, in the absence of government, to use force to defend themselves or others. Something Aquinas does address, however, is the question of why individuals cannot make law, given that individuals are able to direct each other to the kind of virtue and hence happiness that law also aims at. Aquinas’s answer is that individuals do not have the right to use coercion to force people towards virtue the way that law does, a claim that the libertarian would not only strongly oppose, but which, as we shall see in subsequent posts, contradicts Aquinas’s own later express denial that law is an effective means of bringing about virtue (see ST I-II.95.1 and 96.2).

The fourth and final part of Aquinas’s definition of law is that it needs to be promulgated (ST I-II.90.4), a requirement that, on the one hand, rightly excludes such unjust and tyrannous practices as ex post facto laws (laws criminalizing and punishing behavior after the fact) and secret laws. On the other hand, the libertarian might rightly ask whether Aquinas’s promulgation requirement would be quite so necessary if law were properly limited by the non-aggression principle in the first place, a principle whose truth is (as Aquinas’s own understanding of the largely non-aggressive “law of nations” would suggest) already a matter of universal, natural-law “promulgation.”

Much more could be said, both pro and con, by way of a libertarian evaluation of Aquinas’s famous and influential definition of law, but the foregoing gives at least the broad outlines of where the two traditions stand with respect to each other. For the libertarian, as for Aquinas, law is an ordinance of reason, for the common good, made either by the community or its representatives, and promulgated. For each part of this definition, however, the libertarian would add important qualifications and, in places, even corrections: law is a command of reason, but a command of reason specifically as it concerns the use of coercion, something Aquinas omits from his definition here but includes in it elsewhere (ST I-II.96.5). Law, for the libertarian, is also ordered to the common good, but not the common good of a shared, “universal happiness,” which Aquinas himself fails to show, but the much more limited common good that is both morally and practically achievable by coercive means, namely the protection of persons and property from acts of aggression. Libertarian law is also law made by the community, but because the community is composed of individuals, the community has no right to make coercive laws that go beyond the coercive rights of its individual members. And law, finally, must be promulgated, but in keeping with Aquinas’s first point about law’s rationality, law also ought to be limited to that (non-aggression) principle which reason itself has already universally promulgated to all men.

Division of Law: Eternal, Natural, Human, and Divine

The next chapter of his “Treatise on Law” has proven equally influential, as he sets out to synthesize biblical, Greek, Roman, and early Christian categories of law into a single, integrated system. In Aquinas’s schema, there are four principal kinds of law: (1) eternal law, by which God providentially rules the entirety of his creation; (2) natural law, which is the moral-law portion or subset of the eternal law that applies to human beings in particular; (3) human law, or those laws made and enforced by human beings within the context of political society; and (4) divine law, which are all the laws revealed by God in both the Old and New Testaments of Scripture. Aquinas didn’t invent any of these categories of law; what he did was merely define and distinguish them in a new and helpful way that would become the standard for many later thinkers. As we shall see, each of these kinds of law has an important role to play in a Christian libertarian theory of law.

Aquinas’s first category of law is also the most universal: eternal law refers to the comprehensive order of things by which God providentially directs the entirety of his creation to its God-ordained end (ST I-II.91.1). From the galactic to the sub-atomic, absolutely everything that exists is ruled by God’s eternal law. Far from this universal law being a threat to human freedom, however, for Aquinas, as for the Christian libertarian, it is God’s rule over everything that not only makes possible human freedom, but is also what imbues that freedom with its deepest possible significance. The eternal law is what gives the world its dependable, causal structure, without which it would be impossible to reliably order our own actions in the human sphere. More than this, in God’s cosmic economy, human beings have been granted, by virtue of their free will, a privileged role in helping realize the divine order of things, such that apart from the exercise of their freedom, God’s own purpose for his creation would go frustrated and unfulfilled.

Aquinas’s second category of law is the natural law (sometimes called the moral law), which is that subset of God’s eternal law dealing with human actions in particular (ST I-II.91.2). All creatures have certain inbuilt “inclinations” to behave according to their God-given nature; what makes human beings unique is their power of reason by which they are able to intellectually observe and grasp what their natural human inclinations are, formalizing them into “rules” to guide their future actions. And these natural human inclinations, formalized into rules by reason, are what comprise the natural law. As such, the natural law contains the universal, rational, and objective standards of moral right and wrong that differentiate those good actions which tend to fulfill our human nature and promote human flourishing from those evil actions that don’t.

An important application of this idea is that the natural law is also responsible for distinguishing those coercive actions that are moral from those that are not, though where the dividing line between the two lies precisely is a question Aquinas unfortunately never directly deals with. Properly understood, what libertarianism represents is merely the attempt to provide just such a universal, rational, and objective natural law standard for the moral use of coercion, and that standard is the Non-Aggression Principle. On account of man’s nature as a free, self-directing agent, only those actions involving aggression against the person or property of others may themselves be coercively suppressed.

This brings us to Aquinas’s third kind of law, human law, by which he means those positive or civil laws made by human beings living in community with each other. According to Aquinas, the reason we need human law is because natural law provides only the most general principles of human practical reason, whereas human law takes these general moral rules and makes them more specific (ST I-II.91.3). There are a couple of problems, however, with this account of the relationship between human law and natural law, the most important of which, from the libertarian’s perspective, is that the real reason human law is necessary in comparison with natural law is that human law represents those parts of the natural law that are or ought to be subject to coercive enforcement.[1] This is yet another area, accordingly, where Aquinas’s failure to attend, in more libertarian fashion, to the inherent coercive nature of law arguably leads him to be less precise in his own thinking about human law than he otherwise might have been.

Aquinas’s fourth and final category of law is what he calls divine law, which refers to any law that is revealed in Sacred Scripture (ST I-II.91.4). Divine law, therefore, is distinguished not by what it teaches (since all of the moral teaching of Scripture, for example, is the same as the natural law), but by how it teaches it: the divine law is law that is made known, not by natural reason, but by supernatural revelation. Of the four reasons Aquinas gives for why divine law is necessary, the last two of which are of particular interest to us here: divine law is necessary because human law can only regulate outward action, whereas divine law is able to regulate the “interior movements” of man; and divine law is necessary because even in matters of outward action, human law is not competent to prohibit all evil deeds, whereas divine law condemns even those evil acts which human law must permit.[2] Similar to natural law, then, and consistent with libertarianism, divine law testifies to the radical limits of human law: the latter can only judge outward actions, and even then, it must permit many actions that it belongs only to divine law to prohibit.

Inasmuch as divine law is simply the law of Scripture, Aquinas further divides it into the familiar, biblical distinction between the “Old Law” of the Hebrew Scriptures and the “New Law” of the Christian Gospel (ST I-II.91.5). The main difference between the two, as Aquinas represents it here, is that whereas the Old Law primarily directed man to his more proximate, this-worldly good of an imperfect, temporal happiness, the New Law is what directs man to his ultimate, eternal good of perfect happiness in God. This means that, although a part of divine law, the Old Law, at least in its judicial or political capacity, actually served the same role as human law does in other societies. This leads Aquinas to view the Old Law (despite its divine origins) as being subject to much the same limits as that faced by human law, namely that neither of these can “control the mind” but can at best only “restrain the hand.” This is because the Old Law moved its subjects, not through love (as in the New Law of the Gospel), but through “fear of punishment.” Once again, and in libertarian fashion, we see Aquinas’s notion of divine law significantly restricting what law backed by coercion can actually accomplish.[3]

The Effect of Law on Man

After defining what law is (law is an ordinance of reason, for the common good, made by one with authority, and promulgated), and after classifying its major species (eternal law, natural law, human law, and divine law), Aquinas turns next to the main effects of law. What is it, exactly that law does? Aquinas’s answer, in summary, is that, first, law makes men good, and second, that law does this by four principal activities, namely commanding, prohibiting, permitting, and punishing actions. We will examine his arguments for each of these answers in turn, as well as what a libertarian response to them might be.

According to Aquinas, the proper effect of law is to make men good (ST I-II.92.1). On the face of it, his view might seem anti-libertarian, yet as we shall see, the exact relationship is somewhat more complicated than this. Aquinas bases his argument with his earlier definition of law: law is a command of reason made by a ruler or lawgiver (whom he also identified as either the whole community or its appointed representative). Law, then, involves a relationship of ruler and subject. From here, Aquinas makes observes that if there is a relation of ruler and subject, then there must be a specific virtue or excellence that is proper to the subject as subject, a virtue, that is, by which an individual’s subjection to his ruler is made perfect or complete.

While the idea of being properly subjected to one’s ruler might, to the libertarian, sound less like a virtue than a vice, the idea itself is not, in fact, incompatible with libertarianism. The first thing to note is that the virtue Aquinas has in view, at least at this initial stage in his argument, does not concern moral virtue in general, but only the very limited and specific virtue of simply being appropriately obedient to one’s ruler, a virtue that, as Aquinas himself will later acknowledge, would also involve being appropriately disobedient if the law or lawgiver were in fact unjust. And even the libertarian might allow that, provided the law is just, prohibiting only acts of aggression against others, there would or at least could be such a thing as the virtue or moral perfection on the part of subjects in being rightly subordinate to such just laws.

Where the disagreement begins to arise, rather, is also, significantly, where the logic of Aquinas’s argument begins to break down. From the unobjectionable claim that the virtue of a subject as subject lies in his being properly subordinated to his ruler or lawgiver, Aquinas draws the conclusion that law must therefore aim at being obeyed by those who are subject to it. But this doesn’t follow, nor does it seem to be strictly true. While laws are made, to be sure, with the expectation that they will be kept, this is not the same thing as saying that they are made for the purpose of being kept. What is more, to say that every law “aims” at being obeyed is to imply that law-keeping or one’s subjection to law is an end or good for its own sake, rather than the mere means to an end.

Aquinas’s argument only gets more confusing from here. From the above conclusion that law aims at making its subjects obedient to it, Aquinas next infers that the proper effect of law is therefore to lead its subjects to their “proper virtue.” What does he mean by the “proper virtue” aimed at by law? Where initially it was merely the very limited virtue of a subject as a subject, Aquinas now asserts that, because law aims at the “true good,” it does not aim at making men good merely “relatively,” that is in a particular way or with respect to a particular good, but aims instead at making men good “simply” or “absolutely,” that is, without qualification. Thus, from the unobjectionable starting point that law makes men good in that limited respect in which men are subjects, he arrives at the illegitimate conclusion that law makes men good in that complete or total respect in which men are men.

For the libertarian, accordingly, the real objection to Aquinas’s thesis lies not with his view that law makes men “virtuous” or “good” in itself, but, first, in his suggestion that law exists for its own sake by making men good at keeping law; and second, in his unwarranted assumption that the good or virtue that law properly aims at is the “true good,” i.e., the highest good and happiness of the community. But for the libertarian, once again, the end of coercive human law is not (and cannot be) the common good of communal well-being or happiness, but the much more limited, even if necessary and contributory, good of protecting the members of society from aggression against their persons and property.

The second effect of law that Aquinas addresses has to do with four operations of law that the ancient Romans had identified, namely commanding, prohibiting, permitting, and punishing (ST I-II.92.2). What Aquinas does, somewhat ingeniously, is correlate these four Roman categories of the operations of law with the three possible moral states that an action can have. An action is either (1) inherently good, in which case law commands it; (2) inherently evil, in which case law prohibits it; or (3) morally neutral or indifferent (i.e., it can be either good or evil, circumstances depending), in which case law permits it. And in each case, finally, whether law commands, prohibits, or permits an action, what distinguishes law is that it is “the fear of punishment that law makes use of in order to ensure obedience,” making punishment to be the fourth effect of law.

Ingenious as it may be, Aquinas’s account suffers from a problem, which is that it’s simply not the case, even for Aquinas, that law commands an action when it is inherently good, prohibits an action when it is inherently evil, or permits an action when it is morally indifferent. On the contrary, for Aquinas there are many inherently good actions which law does not command, many inherently evil actions which law does not prohibit, and many morally indifferent actions which law often does not permit. What this means is that, of itself, the moral status of an action tells us nothing about whether law does or ought to command, prohibit, or permit that action. What determines an action’s relationship to law, accordingly, must be determined on some other, independent grounds that Aquinas, at least in the present passage, does not specify.

For the libertarian, by contrast, because of law’s coercive nature, whether an action is to be commanded, prohibited, or permitted by law has less to do with the moral status of the action in the abstract, than it does with whether the action involves aggression against the person or property of others. For this reason, it would seem that, of the four activities of law listed by Aquinas, it is actually only the fourth one, punishment, that is in fact a distinctive or proper effect of law as law.

Libertarianism and the Eternal Law

Thus far in our libertarian study of St. Thomas Aquinas’s famed “Treatise on Law,” we have seen Aquinas define law as an ordinance of reason, for the common good, made by one with authority, and promulgated; distinguish four principal kinds of law—eternal law, natural law, human law, and divine law; and address the principal effects of law as that of making men to be good, and of commanding, prohibiting, permitting, and punishing human action. In the next chapter of his study of law, Aquinas returns to take a more detailed examination of the different kinds of law, beginning with eternal law. In so doing, he provides us yet another opportunity to reflect on the relationship between libertarianism and the eternal law.

The eternal law, Aquinas reminds us, is simply the providential pattern by which God, as the supreme artisan and governor of everything that exists, wisely directs the activity or operations of all his creatures towards their respective ends (ST I-II.93.1). And although God’s eternal law for creation as it exists in the mind of God remains an unfathomable mystery to man, it is nevertheless something eminently knowable to man insofar as it is “reflected” and “participated” in by God’s creaturely effects (ST I-II.93.2). Indeed, insofar as it is the eternal law that regulates all of existing reality, giving each creature its determinate nature and stable, dependable, and hence intelligible structure, to know anything at all is ultimately to know something of God’s eternal law.

Of special interest to us here, however, is Aquinas’s question as to whether all other laws, including human law, are or are to be derived from God’s eternal law (ST I-II.93.3). What he says is that human law has the nature of law only so far as it partakes of the ultimate rationality of the eternal law, and that insofar as human law deviates from the right reason of the eternal law, it is an unjust law and actually “has the nature, not of law, but violence.” This is significant: earlier in his Summa Theologiae, Aquinas had defined violence as any movement of a thing that is contrary to its natural inclination, and he had defined coercion in particular as that form of violence that seeks to move a specifically rational being contrary to the inclination of his own will (ST I.82.1). What Aquinas gives us to understand here, accordingly, is that unjust laws are not only contrary to reason because of their legislative content, but due to law’s inherently coercive nature, they are also a matter of violence, inasmuch as they seek to move human beings contrary to their free, rational nature.

In addition to what it commands and prohibits, eternal law also holds implications for what human law must permit. Following St. Augustine, Aquinas acknowledges that human law must permit many actions whose regulation properly belongs to the jurisdiction of God’s eternal law. Aquinas’s primary point, however, is that just because human law permits these things, it does not on that account necessarily approve of them, but may simply allow them as things that human law is unable or unqualified to direct or control. This distinction between permitting something and approving it is an important one for any proper understanding of libertarianism, for it reminds us that what is or ought to be legally permissible does not define or exhaust what is morally permissible. Thus, just because an action is legal does not mean that one therefore has a “right” to commit that action. Legal permission, rather, is less about what a person has a “right” to do than it is about the lack of right that anyone else, including those in civil government, has in using force to stop you from doing it. Eternal law, accordingly, and as Aquinas further implies, therefore determines not only that area where human law is to operate, but also that (much larger) area in which it is not to operate. Not only in what it regulates, therefore, but also in what it doesn’t regulate, human law is to be subject to and derived from the eternal law.

One place where Aquinas’s discussion of eternal law would seem to take an anti-libertarian turn is in the parallel he draws between the way in which God, by means of his eternal law, “imprints” on things the principle of their proper activity and the way human rulers are able to “impress” or “imprint” on the minds of their subjects their own “inward principle of action” (ST I-II.93.5). Human rulers, in short, are able to direct their subjects similar to the way that God does, by moving their own will or natural inclination to act in a desired way. This comes as something of a surprise, since in both earlier and, as we shall see, later passages, Aquinas characterizes human law as much more limited in its reach: working by the coercive means of punishment, human law, like the Old Law of the Hebrew Scriptures, is able to direct only the “hand” but not the “heart” or mind. In the present passage, by contrast, Aquinas adopts a much more optimistic and even paternalistic—if not ultimately idolatrous—posture according to which human law is able to act on and incline human beings to act in a way that only God can do.

The final point Aquinas wishes to make clear in regard to the eternal law is that all affairs of all humans at all times are subject to God’s eternal law, but that this universal subjection to the eternal law is nevertheless accomplished in different ways (ST I-II.93.6). While the good actions of men are subject to the eternal law in an absolute or unqualified sense, evil actions, while not subject to God’s eternal law at one level, nevertheless are not able to escape God’s eternal law at another level. Specifically, Aquinas points out that those who do evil cannot escape the negative consequences that have been decreed for and which inevitably follow their evil actions. The eternal law, accordingly, determines not only how human beings ideally ought to act, but also what the (God-ordained) natural and moral consequences are when they fail to act this way. The lesson to be appreciated by the libertarian here is that, not only must human law not try to govern human actions in a way that only God’s eternal law can do, but the reason eternal law is able to govern human actions is through its establishment of an objective, natural and moral causal order in which, whether in the short term or the long, good actions never escape reward and evil actions never escape penalty.

Libertarianism and the Natural Law

The next category of law to receive Aquinas’s closer inspection is that of the natural law, that subset of God’s eternal law dealing with human action in particular. As we saw in his introductory account earlier, natural law consists of those commands of human reason that are drawn from our natural “inclinations” towards action, inclinations that have been formalized into normative rules for human behavior.

This brings us to the question of what those rational rules of action are, precisely, that the natural law commands us to keep. Just what kinds of action does reason charge us to do? In short, what is the content of the natural law? Aquinas begins his answer to this question by making the interesting claim that the very first rules or “precepts” of the natural law function in much the same way in our practical reasoning (that is, our reasoning about human action) that first principles or axioms function in more theoretical sciences such as geometry. In both cases—in ethics as in mathematics—reason proceeds deductively or logically from self-evident first principles or premises to more derivative, though still necessary, theorems or conclusions. Because the first thing known or grasped by practical reason is the notion of a thing as good, i.e., as something desirable and hence to be sought after in action, the most basic truth, axiom, and hence rule or precept of all practical reason, and hence of the natural law, is the self-evident principle that “good is to be sought after and evil is to be avoided.” This, according to Aquinas, is the very “first principle” of the natural law from which all other precepts of the natural law are derived. The natural law, in sum, consists of all those rules for human action by which a human being is rationally directed towards a real good or away from a real evil. Whenever human beings seek that which is good and avoid that which is evil, they are following the natural law.

This is not to say, however, that the natural law commands every good or prohibits every evil equally or in the same measure. Rather, just as there is a real, objective order or hierarchy to the goods that a human being needs and desires, as well as to the evils that he is to avoid, so there is an order or hierarchy to the natural law precepts directing human action towards or away from those respective goods and evils (ST I-II.94.2). Moving from the more general to the more specific, in the first place is the natural inclination that human beings share in common with all other existing things, namely the desire for self-preservation. For this reason, the natural law commands that (all other things being equal) a person act so as to preserve his own life and avoid those things tending towards his destruction.[4] A second order of natural goods and natural inclinations—and hence a second order of natural law precepts—concern those matters which human beings share with all other animals, including sexual intercourse and the raising of offspring. A third and final order of natural goods, inclinations, and corresponding natural law precepts concern those goods which are proper or specific to human nature itself, including especially the knowledge of God, living in society with other human beings, and the corresponding avoidance of ignorance and giving undue offense to one’s neighbors. Self-preservation, procreation, and the pursuit of God and a well-ordered society: these comprise Aquinas’s well-known “three precepts” of the natural law.

These three precepts, however, are still very general, whereas the natural law in fact directs human beings to every good to which their nature inclines them, a consequence of which is that the natural law is understood by Aquinas to command every act of every virtue (ST I-II.94.3). In a word, the natural law encompasses all of human morality. And although the natural law is one and the same in all men, Aquinas admits that the more we descend into particular matters of detail concerning the natural law, the more difficult it is to know precisely what the natural law teaches (this is one of the reasons Aquinas thinks that Scripture, with its supernaturally revealed divine law, is so important), the result being that men often differ from each other over their understanding of what the natural law actually teaches or requires (ST I-II.94.4). Nevertheless, Aquinas insists that the natural law does not change in its fundamental precepts (ST I-II.94.5), nor can its primary precepts be completely eradicated from the hearts of men, though, again, in some of its more derivative or down-stream precepts he allows that the natural law can be practically erased from the consciences of men through bad customs or habits (ST I-II.94.6).

What might the libertarian make of Aquinas’s above teaching on the natural law? In and of itself, there is little if anything in Aquinas’s traditional account of the natural law that is inconsistent with libertarianism per se, and, indeed, much to commend it. The natural law, as the moral foundation of all human action, and hence of all human law, is objective, universal, obligatory, and knowable, and obedience to or compliance with the natural law is necessary if human beings are to flourish as their God-given nature dictates. As Aquinas will develop later, and in a principle that is arguably the central political insight and application of his doctrine of the natural law, this means that for any human law to be legitimate, authoritative, and hence obligatory, it must legislate in a manner consistent with and in some sense derivable from the always more foundational moral authority of the natural law. Viewed from this perspective, the central thesis of libertarianism might be instructively viewed as merely an attempt to apply this principle a step further: not only must the actions regulated by law be consistent with the natural law, but the regulators’ own act of coercion must likewise be consistent with the natural law, using force to restrain only those violations of the natural law that the natural law itself would require.

Although Aquinas (unfortunately) never develops a consistent natural law ethic of coercion, one natural law principle of coercion we might draw from his above account concerns the variability with which he says the natural law is grasped or known in its more derivative or secondary principles. If it is the case, after all, that the more we descend into matters of detail, the more difficult it is to know the natural law and, hence, disagreements over the natural law arise more frequently, shouldn’t this fact alone have some moral bearing on which parts of the natural law it is in fact natural for human law to try to enforce? According to Aquinas’s own earlier definition of law, a law is only a law if it is clearly promulgated (ST I-II.90.4), but as Aquinas himself will give us to understand later, the most universally promulgated form of human law, because the most directly and clearly derived from the natural law, is the “law of nations,” that body of law affirmed by virtually every political society, and yet which is primarily concerned with such aggressive acts as violence, theft, and fraud. If so, then already in his account of the natural law, it is possible to see the seeds being sewn for a properly libertarian ethic of non-aggression.

Human Law

Having laid its ultimate metaphysical foundation in God’s eternal law governing all created reality, and having then laid its ultimate moral and anthropological foundation in the natural law governing all human action, Aquinas at last turns to the question of man-made law, or what he calls human law. He raises four questions in particular about human law: (1) What is its use? (2) From whence do political communities derive human law? (3) What are some of human law’s leading “qualities” or aspects? And (4) what are some of the principal divisions of human law? Both the questions themselves, but especially how Aquinas answers them, will prove of significant interest to the libertarian.

Aquinas begins his discussion of the usefulness of human law (ST I-II.95.1) by quoting a highly suggestive passage from the early medieval encyclopedist Isidore of Seville (AD 560-636): human laws are made in order that through fear “human audacity might be held in check, that innocence might be safeguarded in the midst of wickedness, and that the dread of punishment might prevent the wicked from doing harm.” From here Aquinas argues that while the private admonition of parental training is the normal and best way of inculcating virtue in people, human law is nevertheless necessary for those “depraved” individuals who have either failed to receive such training in virtue or, because of their being “prone to vice” or otherwise “not easily amenable to words,” are only able to be “restrained from evil by force and fear.” In this way, such men might be kept from doing evil and “leave others in peace,” and hence over time might even be habituated to do that good voluntarily and virtuously what they previously did only under compulsion.

Aquinas’s account of the usefulness of human law is remarkable in that it involves a much more libertarian perspective on law than Aquinas has given thus far. Previously in his “Treatise on Law,” Aquinas had identified the end of law as nothing less than the “universal happiness” of the community as a whole (ST I-II.90.2), as being more effective than private forms of admonition because of its use of coercion (ST I-II.90.3, reply 2), and as able to make men to be good, not in a relative but in an absolute sense, making men to be good as men (ST I-II.92.1). Here, however, Aquinas would seem to set law’s sites much, much lower: coercive human law doesn’t positively bring about communal happiness so much as it merely helps ward off a particular kind of vicious behavior; its use of coercion makes it in important ways actually less effective in leading to virtue than the verbal or persuasive means of private admonition; and thus law makes men good not absolutely speaking, but in the relative sense of forcing only some them to be less bad than they otherwise might be. However non-libertarian Aquinas’s general account of human law may be, his account of specifically its usefulness is as libertarian as one could ask for.

After its usefulness, Aquinas next inquires into human law’s origins: from where do we get human law (ST I-II.95.2)? The answer is one that we have seen before: if human law is to be legitimate and just, it must be derived from the natural law. Aquinas here distinguishes two different ways in which this may happen. First, and most straightforwardly, a human law may be derived from the natural law by way of strict logical deduction, the way a conclusion is derived from its premises in a syllogism. The example he gives is how, from the general natural law principle that “one should do harm to no man,” we deduce the human-law conclusion that “one must not kill.” The second way a human law may be derived from natural law is less clear cut, as it involves a more indefinite, discretionary, and even creative act that Aquinas calls a “determination of certain generalities,” in which a general principle could be reasonably applied in any number of ways, leaving the lawmaker to make a prudential decision as to how it might best be applied in the context of a particular community. Here the example is how, although the requirement that an act be punished may be deducible from the natural law, just what that punishment should be is not so derived, but is something that must be prudentially resolved, specified, and in that sense “determined” from the natural law.

The significance of Aquinas’s discussion of the twofold origin of human law in the natural law perhaps become most clear in the context of the last question he raises about human law, in which he inquires into some of the principal divisions of human law (ST I-II.95.4). The most important division Aquinas incorporates into his account is the classic Roman law division of human law into the “law of nations” (ius gentium) on the one hand, which are those laws that all or nearly all political societies hold in common, and “civil law” (ius civile) on the other, which are those laws that are peculiar to a particular society. Ingeniously, what Aquinas does is identify this historic, Roman law distinction between the law of nations and civil law with his above, epistemological distinction between the two ways in which human law may be derived from natural law. Thus, on Aquinas’s interpretation, the law of nations that all societies hold in common corresponds with those human laws that are logically deduced from the natural law, and which he illustrates now with the law of nations stipulation that there should be “just buyings and sellings,” but which he says also includes those laws “without which men cannot live together.” The Roman category of civil law, by contrast, and in which one society differs from another, Aquinas identifies with second way of deriving human law from natural law, namely “by way of particular determination.”

While Aquinas gives here a somewhat more idealized account of the law of nations than was really historically the case, his discussion is nevertheless quite suggestive from a libertarian point of view.[5] Aquinas’s two examples here of a human law “deduction” from the natural law are the prohibition of murder and the requirement of justice in exchange, but to which list he would also add such laws concerning the prohibition of treason, rape, fraud, theft, and the general provision for the punishment of crime, all of which involve either acts of aggression (or the threat thereof) against others or else the community’s coercive, punitive response.[6] Thus, although Aquinas never directly develops, as the libertarian attempts to do, an ethic of human law coercion from the natural law, he implies both the possibility of deducing such an ethic, and that the result of such a deduction is, for all intents and purposes, a libertarian ethic of non-aggression. This would suggest, moreover, that all of the other, higher functions that Aquinas assigns to human law, principally its directing community to the common good of universal happiness and of leading men to virtue, fall under the category of the civil law “determinations” of the natural law that vary from community to community.

Understood in these terms, accordingly, the debate between the libertarian and Aquinas may be summarized thus: whereas the libertarian believes that human law ought to be limited to those uses of coercion expressly warranted and required by the natural law (and hence recognized by virtually all nations), Aquinas believes that each political society is also permitted, in the interest of promoting virtue and the common good, to use coercion in enforcing its own unique set of “civil laws” that go above and beyond the libertarian law of nations. To this, however, the libertarian could meaningfully reply that, however important such ends might be, to use coercion to achieve such ends is itself a violation of the non-aggression ethic logically required by the natural law, and therefore not to be attempted.

The Power of Human Law

One question Aquinas poses that is of particular interest to us here asks whether human law has the power of repressing all human vice (ST I-II.96.2). Although Aquinas believes, as we have seen, that one of the main effects of law is to make men good, he denies here that law is able to forbid all sin, and his explanation leads him into one of his most libertarian statements in all of his writings. Law, he states, must be suitably tailored to the moral condition of the subjects that it regulates, meaning that the less virtuous a society is, the more permissive its law needs to be. Since most human beings, however, are imperfect in virtue, the vices which law characteristically ought to prohibit are only “the more grievous” kind which most men are able to avoid, such as murder and theft, and which Aquinas describes as involving the “hurt” and “assailing” of others, in which “one’s neighbor is injured.” Thus, although the way Aquinas gets there is utilitarian in the extreme, his conclusion is fully libertarian: law seeks to prohibit not all vices, but primarily those that involve aggression against others.

Aquinas’s libertarian moment, however, is short lived, for in the very next section he poses the question of whether law has the power of commanding any act of virtue, to which he answers “yes” (ST I-II.96.3). His view is not that law can command all acts of all the virtues all the time, for this would amount to claiming that law can prohibit all vices after all. Rather, his claim is the slightly more modest one that, in principle, there is no virtue or act of virtue that is in inherently “off the table” where law is concerned. His reasoning is that because all the virtues are ordered towards and contributory to the common good, and the common good is the whole aim or purpose of law, there can be no virtue that is off limits to law’s purview or prescriptive activity. Nevertheless, Aquinas recognizes that, practically speaking, not every virtue is an equal priority to the common good and therefore of equal priority to the law.

The libertarian need have no objection to Aquinas’s claim that all virtue and all acts of virtue contribute to the common good. Where the objection comes in, as we have seen in earlier passages, is with Aquinas’s construing the common good with which coercive human law is concerned in so broad a manner. As we have just seen, Aquinas denies that human law has the power to regulate all vice, thereby implying that the common good able to be achieved by coercive human law is not and cannot be the thick one of communal happiness and positive virtue, but the comparatively thin (and libertarian) one of merely prohibiting those more egregious acts of aggression against others that make civil society to be impossible. In these two consecutive claims about the power of human law, accordingly, we see the tension, and really, the contradiction, at the heart of Aquinas’s entire political philosophy as a whole, namely that between his libertarian and realist appreciation of the radical limits of coercive human law on the one hand, and his Aristotelian and naïve optimism about its purported abilities on the other.

Aquinas’s next question on the power of human law involves him in swinging once again back in a more appreciably libertarian direction, as he asks whether human law has the power to bind a man, not just in his bodily actions, but now in the inner recesses of his own conscience (ST I-II.96.4). Do man-made laws have the ability morally, as opposed to merely physically, to compel or oblige action and obedience on the part of other men? Aquinas answers by stating that laws oblige only so far as they are just, but devotes even more space to discussing those circumstances in which a law is unjust, and hence not binding on the conscience. This occurs when a law is either contrary to the common good, accrues only to the private good of the ruler, goes beyond the authority of the ruler, or imposes burdens unequally on the community. Nevertheless, even when a law is unjust and so does not bind the conscience directly, Aquinas allows that there may nevertheless be an obligation to obey the law, not because it is a law, but in order to avoid offending the conscience of others or causing a public scandal.

Aquinas’s teaching on law and conscience is significant as it contains arguably his most direct instruction on the important question of civil disobedience: when is it morally permissible for individuals to disregard the commands of civil government? Related to this, it also contains perhaps his most direct confrontation with the doctrine of legal positivism so dominant in the practice of law and politics today. According to legal positivism, a law is any rule that has been enacted and is enforced by a recognized legal authority, with the implication that justice is whatever the law says is just.[7] For Aquinas, by contrast, whether something is a law is not a matter of the lawmakers merely saying that it is a law or that it is just. Rather, a law is only law, and hence binding on the conscience, insofar as it is just, where the justice of a law is determined not by the law itself but by such external and objective factors as whether the law is truly ordered to the common good, made by one with real authority, and equitably distributing the burden of law throughout society. Here Aquinas may also be seen as espousing a form of philosophical vigilantism, insofar as he implicitly recognizes the responsibility that every individual inescapably has, as a free, rational agent, to pass judgment on the law and to determine its actual lawfulness as a law.

We conclude our consideration of Aquinas’s discussion of law’s power with his question on whether the power of law is over all men, good and bad alike, or only over the wicked (ST I-II.96.5). Insofar as law is a rule of human action, he says that it applies to all men, but insofar as it is a rule of human action that comes with coercive power, he says that law only applies to the wicked, since the virtuous are those who keep the law out of principle and not force. Here Aquinas may be seen attempting to resolve the ambiguity we have seen in his philosophy of law thus far, namely his attempt to have law function simultaneously as a coordinative principle for the whole community but as coercive principle only for the wicked. To this, however, the libertarian might respond by asking whether it is reasonable to assign one and the same institution of human law both of these purposes at once. Granted that all the members of the community need rules, customs, and the like to better coordinate their actions towards many higher (and lower) order goods, and granted that some members of the community, namely the wicked, need coercion to deter them from acts of aggression against others, the question remains as to why the coercion used in the latter should also be used in the case of the former. Given, in other words, Aquinas’s own acknowledgment of the inherent limits of the use of coercive human law, and his general view of the importance of free, rational human beings being able to direct their own actions, why should we expect the rules designed for the harmonious collaboration of society to be enforced by the same coercive means as those laws intended to protect members of society from acts of aggression? Aquinas never answers this question, but it is one that cuts to the heart of the debate between his political philosophy and that of the libertarian.[8]


[1] Another problem with Aquinas’s claim that human law is necessary in order to make the natural law more specific is that it doesn’t actually fit with Aquinas’s own theory of the natural law, which for him includes not just the most general principles of human practical reason, but also any of the more determinate moral principles that may be derived from them. Rather, and as we saw in the previous post, what really differentiates human law for Aquinas is that they consist of those natural law rules that direct human action specifically towards the common good.

[2] The first two reasons Aquinas gives for divine law are (1) because man is ultimately ordered to a supernatural end that can only be achieved by the supernatural means of special, divine revelation; and (2) because even in those moral matters where divine law and natural law overlap (as in the case for example, of the Ten Commandments), divine revelation is able to make those moral laws known in a quicker, easier, and surer way than unaided human reason is able to do.

[3] Aquinas concludes his discussion of the principal kinds of law with something of a footnote on the Christian and specifically Pauline idea of there being a “law of sin” (ST I-II.91.6). Aquinas’s concern here is to observe that, even when human beings transgress the law of God, far from escaping God’s law, their sin simply delivers them over to yet another law established by God, namely the “law of sin” (Rom. 7:25), in which the sinner is no longer able to obey his higher, free and rational nature, but is instead enslaved to his lower, sensual nature. Here, too, there is an important libertarian lesson for human law to observe, which is that on many matters, human law must not try to punish what God has forbidden so much as stay out of the way and let God’s own “law of sin” do its providential work.

[4] I add the qualification “all other things being equal” to the principle of self-preservation, for as Aquinas recognizes, of course, there are certain goods which are greater than, and so are to be valued higher than, our own life, in which case it is rational, natural, and moral for us to risk and even sacrifice our own lives for the sake of these higher goods. This doesn’t alter the case, however, that the inclination towards self-preservation is natural and hence part of the natural, moral law.

[5] The law of nations, for example, traditionally also included such miscellaneous rules as regulations over the occupation of fortifications, the taking of captives in war, slavery, building codes, peace treaties, marriages with foreigners, respect for parents, and proper religious observances, all topics that would not seem to fit Aquinas’s notion of a logical “deduction” from the natural law. Jose Manuel De Aguilar, “The Law of Nations and the Salamanca School of Theology,” The Thomist, vol. 9, no. 2 (April 1946): 190-200.

[6] John Finnis, Aquinas (Oxford: Oxford University Press, 1998), 266.

[7] An early expression of such legal positivism is Thrasymachus in book one of Plato’s Republic when he defines justice as “the advantage of the stronger.” Law and justice, in other words, are simply whatever those in political authority say that they are.

[8] Elsewhere Aquinas himself implies the possibility of a more libertarian division of labor between the two different kinds of rule for human action—the coordinative and the coercive—being suggested here. Following Aristotle, for example, Aquinas routinely distinguishes between “royal” or “political” rule on the one hand, in which he says subjects are not forced to obey but are actually free and even have a “right” to disobey, and “despotic” rule on the other, where there is no such freedom.[2] An application of this perspective would seem to be as follows: whereas those laws protecting against acts of aggression are and ought to be “despotic” in their use of coercion, those “royal” directives otherwise responsible for directing the community towards the common good ought to be ones that the wise and virtuous can and sometimes will depart from.