Lesson 11: Natural Law
A recurrent feature of magisterial documents of the Catholic Church, when they bear on moral matters, is to insist that there are guidelines for human action that are available to anyone, believer and non-believer alike. Not only does the Church proclaim the moral demands that Christian faith imposes on its adherents, she also proclaims and defends natural morality. It is little wonder that this has led some to think of natural law as a peculiarly Catholic tenet. The Church takes on the task of defending the natural without in any way smudging the difference between the natural and the supernatural.
Important as the doctrine of natural law is to the moral thought of St. Thomas, he does not treat it ex professo save on one occasion -- but this is true of any number of his key doctrines, e.g. analogy. The treatment of natural law occurs within the treatise on law in the First Part of the Second Part of the Summa theologiae The treatise begins, appropriately enough, with a definition of law. Thomas asks if law is something of reason, whether it is ordered to the common good, whether it is formed by the one having charge of the community and whether promulgation is of its essence. The answers to these questions, when collected together, tell us what law is.
Et sic quatuor praedictis potest colligi definitio legis, quae nihil est aliud quam quaedam rationis ordinatio ad bonum commune, ab eo qui curam communitatis, promulgata. --IaIIae.90.4. c.
The definition of law can be gathered from these four: law is nothing other than a promulgated rational ordering to the common good by the one who has charge of the community.
This is the first or ordinary sense of the term. If asked what a law is, we would mention some civil ordinance governing conduct with an eye to the common good. Not just any citizen can enact a law: status and authority is needed for that. A law can only bind if it is made known to the citizens, though ignorance of the law is no excuse if the citizen has not acquainted himself with the promulgated ordinance. With this definition fixed and clarified, Thomas then asks if there are different kinds of law.
If we were to answer that question by saying that there are federal, state and municipal ordinances, that there are laws governing the conduct of lawyers, of physicians, of motorists, etc. we would quickly come up with a great variety of laws, to each of which the definition applies straightforwardly. These, we might say, are all laws in a univocal sense of the term; that is, the same account of the term 'law' would be given when applied to each of them. This is not the kind of diversity Thomas is referring to.
The kinds of law he enumerates in Question 91 are these: eternal law; natural law; human law; divine law, and the law of lust. If we asked which of these kinds would save the definition of Question 90 without any need for adjustment we would of course say human law. Thus, the definition of law with which the Treatise on Law begins, applies without argument to only one of the kinds of law Thomas goes on to enumerate. If the term and account of 'law' with which he begins are to apply to these other kinds, adjustments will have to be made. They will not all be called law in a univocal sense of the term, but rather analogically.
The primary analogate of law is the kind that pops immediately into mind and whose definition is established forthwith. The other kinds of law will be called law with reference to this controlling instance and will be more or less like it.
If this is so, why does Thomas mention the eternal law first when he enumerates the different kinds of law? A consideration of what he means by eternal law tells us why.
Respondeo dicendum quod, sicut supra dictum est, nihil aliud est lex quam quoddam dictamen practicae rationis in principe qui gubernat aliquam communitatem perfectam. Manifestum est autem, supposito quod mundus divina providentia regatur, ut in Primo (q. 22) habitum est, quod tota communitas universi gubernatur ratione divina. Et ideo ipsa ratio gubernationis rerum in Deo sicut in principe universitatis existens, legis habet rationem. Et quia divina ratio nihil concipit ex tempore, sed habet aeternal conceptum, ut dicitur Proverbs 8, 23, inde est quod huiusmodi legem oportet dicere aeternam. -- IaIIae.91.1.c
I reply that we must say that, following what was just established, law is nothing other than a dictate of practical reason on the part of the prince who governs a perfect community. But it is clear that, given that the world is ruled by divine providence, as was shown above, the whole community of the universe is governed by the divine reason. Therefore that very notion of the governance of things existing in God as the prince of the universe, has the note of law. And, because the divine reason conceives nothing temporally, but has an eternal concept, as is said by Proverbs 8, 23, this law must be called eternal.
The divine causality from which the universe flows is a knowing act on God's part. What is created is both established and governed by this causality and because of the latter we speak of God's providing for his creation. When we think of this on an analogy with an earthly prince fashioning rules of conduct for those in his realm, we speak of the divine providence as a law, indeed an eternal law since the divine thinking is not a temporal process but from all eternity. [The reference to a 'perfect' community is meant to distinguish the state or city from the family or lesser groupings which are not sufficient unto themselves. A parent's orders are not law in a full sense of the term.]
If divine providence is a law because we can liken it to law in the primary sense, it is in itself prior to human laws. Nothing is prior to God, all creatures and creaturely activities are subsequent to and dependent upon him. Earthly princes making laws are able to do so only because the universe is what it is and is governed as it is. Divine providence, eternal law, is first of all laws. But this does not mean that it is the first thing we mean by 'law.' We have here a situation which is repeated in every case where a name is analogically common to God and creature. Creatures are more easily known by us than God, of course, and our talk reflects this. We speak first of the things we know first. But sometimes terms fashioned to signify creatures come to be used of their first cause as well. Words which first mean created perfections, subsequently and derivatively signify the divine. But God is prior to all creatures: without his causality, they would simply not be. This is why we distinguish the order of the name from the order of the things named. In the order of the name or word 'law', human law is first, and eternal law second. In the order of the things named, eternal law is first and human law derives from it.
Natural law is mentioned second because, ontologically, it falls between eternal law and human law. This is abundantly clear from the account Thomas gives of 'natural law' in article 3 of Question 91.
The eternal law, divine providence, can be said to be 'in' something in several ways, in the way that any rule or measure can be said to be in the measurer or ruler and in the measured and ruled. Thus, while eternal law is in the divine mind in the first sense, it is in the things subject to God's governance in the second sense. A sign of this is the more or less predictable behavior of things given the nature given it by God. Eternal law is in everything measured or ruled by it. It is the special way in which the human agent is measured by eternal law that leads to talk of a distinct law, natural law.
...omnia participant aliqualiter legem aeternam, inquantum scilicet ex impressione eius habent inclinationes in proprios actus et fines. Inter cetera autem rationalis creatura excellentiori quodam modo divinae providentiae subiacet, inquantum et ipsa fit providentiae particeps, sibi ipsi et aliis providens. Unde et in ipsa participatur ratio aeterna, per quam habet naturalem inclinationem ad debitum actum et finem. Et talis participatio legis aeternae in rationali creatura lex naturalis dicitur. -- IaIIae.91.2.c
. . . all things participate in some way in eternal law insofar as from its impression they have inclinations to their proper acts and ends. But among them the rational creature is subject to divine providence is a more excellent way, insofar as he becomes a participant in providence, providing for himself and others. Hence in it too eternal reason is participated in, thanks to which it has a natural inclination to its fitting end and act. This kind of participation in eternal law on the part of the rational creature is called natural law.
Natural law is a special case of the creaturely participation in eternal law -- by being governed by it. To be governed by eternal law does not involve awareness or knowledge, by and large, but in the case of the human agent, there is not only governance by the divine reason, but self-governance as well. The human agent thus imitates the divine agent and his sharing in eternal law is thus appropriately recognized as a special kind of law. Law, we remember, is something of reason.
Thomas goes on to speak of human law and makes it clear how it depends on the natural law whereby the human agent governs himself as a measured measure. If law is a dictate of practical reason, we should remember that practical reason describes a certain trajectory or process in its operation. The same is true of theoretical reason. Our thinking begins with sweeping generalities whose truth no one would doubt and proceeds to more specific knowledge where of course complete certainty is harder to come by. The starting points of reasoning, its principles, are called self-evident because knowledge of their truth is not dependent on knowledge of the truth of something else. As reason moves off from such principles, it formulates judgments which depend upon the starting points either because they specify them in some way or because they derive from specifications of them. The ease with which we know starting points is the basis for saying that we know them naturally, as opposed to the effort and inquiry more specific truths cost. In the case of practical reasoning, the particular ordinances are called human law -- provided that all the notes of the definition of law first given obtain. Obviously, not every use of practical reason issues in laws even though it is undertaken to govern my conduct here and now. My ultimate judgment of what I must do does not acquire the status of law. But what is called law in the proper sense is a specification by the practical reason of the legislator.
Once we see how natural law is located between eternal law and human law, we are ready to understand its more frequent description. We find this in Question 94 which is dedicated to the discussion of natural law.
The precepts of natural law are the things we naturally grasp as to how we ought to act. The grasp or hold of such guidelines is a kind of habit of the mind, but natural law is what is grasped or held by that quasi-habit. [Article 1] The second article asks how many precepts of natural law there are. In pursuing an answer to it, Thomas spells out the analogy between theoretical and practical reason he has already invoked.
Respondeo dicendum quod, sicut supra dictum est, praecepta legis naturae hoc modo se habent ad rationem practicam, sicut principia prima demonstrationum se habent ad rationem speculativam: utraque enim sunt quaedam principia per se nota. Dicitur autem aliquid per se notum dupliciter: uno modo, secundum se; alio modo, quoad nos. Secundum se quidem quaelibet propositio dicitur per se nota, cuius praedicatum est de ratione subiecti: contingit tamen quod ignoranti definitionem subiecti, talis propositio non erit per se nota. Sicut ista propositio, Homo est rationale, est per se nota secundum sui naturam, quia qui dicit hominem dicit rationale: et tamen ignoranti quid sit homo, haec propositio non est per se nota. Et inde quod sicut dicit Boetius, in libro De hebdomadibus, quaedam sunt dignitates vel propositiones per se notae communiter omnibus: et huiusmodi sint illae propositiones quarum termini sunt omnibus noti, ut Omne totum est maius sua parte et Quae uni et eidem sunt aequalia, sibi invicem sunt aequalia. Quaedam vero propostiones sunt per se notae solis sapientibus, qui terminos propositionum intelligunt quid signicent: sicut intelligenti quod angelus non est corpus, per se notum est quod non est circumscriptive in loco, quod non est manifestum rudibus, qui hoc non capiunt. -- IaIIae.94.2.c
I reply that we must say that, as was stated in q. 91, a. 3, the precepts of the law of nature are to practical reason as the first principles of demonstrations are to speculative reason, for both are self-evident principles. But something is said to be self-evident either as such or with respect to us. A proposition is called self-evident as such when its predicate enters into the account of its subject, though it can happen that for one who does not know the definition of the subject the proposition will not be self-evident. The proposition 'Man is rational' is as such self-evident, since whoever says man says rational, but for one who ignorant of what a man is the proposition would not be self-evident. That is why Boethius says in the De hebdomadibus that there are axioms or self-evident propositions known to all and these are propositions whose terms are known to everybody. E.g. 'Every whole is greater than its part,' or 'Things equal to some third thing are equal to one another.' Other propositions are self-evident only to the wise who know what their terms mean. E.g. to someone who knows that an angel is not a body it is self-evident that an angel is not circumscriptively in place, something not manifest to the uninstructed who don't know this.
The notion of a self-evident proposition, one knows in itself as opposed to being derived from other propositions, has its natural habitat in theoretical or speculative reason. In this passage Thomas proposes to extend the notion of self-evident proposition from the theoretical to the practical order, thus providing himself with the means to give a second description of natural law, viz. Natural law means the self-evidently true precepts that govern human action. It is imperative to grasp the notion of the self-evident in its native habitat before seeing how it can be extended to the practical order.
A proposition is self-evident as such when its predicate enters into the definition of its subject. If the definition of man is rational animal, then the proposition "Man is rational" is self-evident. Such a proposition is recognized as self-evident by one who understands the meaning of the constituent terms. The examples given are:
 The whole is greater than its part.
 Two things equal to a third are equal to one another.
It is difficult to imagine someone who doesn't realize that he who gets the whole pie gets more than if he is given only a slice of it. So too if your foot is as large as Emil's and my foot is as large as Emil's, my foot is as large as yours, neither of us being Emil. But there are those who are baffled by
 Angels are nowhere.
This was the point of pointing out that there is no limit to the number of angels who could be on the head of a pin. It is not that things would get crowded but that angels being what angels are don't take up space, they are not in place the way pins and bowling balls and the like are. Asking how many angels can be on the head of a pin calls attention to a category mistake. If someone said
 I have the number 7 in my pocket
we would assume he was telling a joke. The number 7 just isn't located the way keys and coins and handkerchiefs are. But  and  are self-evidently true and false, respectively, once we know the nature of what is being talked about.
What is important for our purposes is that Thomas means to extend talk of self-evident propositions to the practical order. A sign that something is a self-evident proposition is that it makes no sense to deny it. Theoretical self-evident propositions are defined as those whose predicates enter into the definitions of their subjects. [This is the first kind of perseity that Aristotle lists and a thorough discussion of the topic would require asking whether the other modes of perseity or self-evident can travel from the theoretical to the practical order.] Some such propositions are not known to be such by those who do not understand their terms. So too we can imagine a practical precept in the area of medical ethics the meaning of whose terms are known only to the instructed. For most of us, the precept would baffle; for the instructed it might be utterly nongainsayable -- to deny it would be nonsense.
In his autem quae in apprehensione omnium cadunt, quidam ordo invenitur. Nam illud quod primo cadit in apprehensione, est ens, cuius intellectus includitur in omnibus quaecumque quis apprehendit. Et ideo primum principium indemonstrabile est quod non est simul affirmare et negare, quod fundatur supra rationem entis et non entis: et super hoc principio omnia alia fundatur, ut dicitur in IV Metaphs. Sicut autem ens est primum quod cadit in apprehensione simpliciter, ita bonum est primum quod cadit in apprehensione practicae rationis, quae ordinatur ad opus: omne enim agens agit propter finem, qui habet rationem boni. Et ideo primum principium in ratione practica est quod fundatur supra rationem boni, quae estBonum est quod omnia appetunt. Hoc est ergo primum praeceptum legis, quod bonum est faciendum et prosequendum et malum vitandum. Et super hoc fundatur omnia alia praecepta legis naturae: ut scilicet omnia illa facienda vel vitanda pertineant ad praecepta legis naturae, quae ratio practica naturaliter apprehendit esse bona humana. -- IaIIae.94.2.c
There is an order among the things that everyone grasps. For that which first is apprehended is being, the understanding of which is included in whatever else one apprehends. Therefore the first indemonstrable principle is Not to affirm and deny simultaneously, which is based on the notions of being and non-being. On this principle all others are based, as is said in Metaphysics 4. Now just as being is the first thing apprehended simply speaking, so the good is what practical reason, which is ordered to some deed, first grasps: every agent acts for the sake of an end, which has the note of the good. Therefore the first principle in practical reason is that which is based on the notion of the good, that is, on The good is that which all things seek. The first precept of the law, accordingly, is that good is to be done and pursued and evil avoided. On this all other precepts of the law of nature are based, such that whatever is to be done or avoided will constitute precepts of the law of nature if practical reason naturally apprehends them to be human goods.
The parallel or analogy between speculative and practical reason is crucial to understanding what is meant by saying that the precepts of natural law are self-evident truths about what we should do, pursue or avoid. Practical reason is not a different faculty than speculative reason, but the extension of reason into the realm of doing or making. This extension entails that what pertains to reasoning as such applies to practical reasoning as well. Thus, to deny or gainsay a precept of natural law is to violate a law of reasoning as such. Thus, one who sought to deny that the good is to be done and pursued and evil avoided would imply that something other than good is to be done, that is, that something other than the good is the good. But this is to affirm and deny at the same time.
Similarly, the first thing grasped by reason, being, what is, is presupposed by the first grasp of practical reason, what is desirable, the good. That which is good is a being, but a being seen in relation to a desirer whose perfection it is. As we have seen above, the theoretical and practical uses of intellect differ, but they are not separate. "It is by extension," Thomas quote approvingly, "that theoretical reason becomes practical." Knowledge of the way things are, knowledge of what we are, provides the theoretical bases for practical reason.
This is clear from the conclusion of the article we have been examining. Our last quotation ended with the observation that precepts of natural law stating what is to be done or avoided are formed from practical reason's recognition of human goods. This recognition is based on our inclinations of which we become aware. Prior to any decision, we like everything else are inclined to preserve ourselves in existence. This inclination is manifest in the desire for food and drink. We don't decide such things are good for us, and then pursue them. We become aware that to be what we are is already to be inclined to them as goods. Like other animals we are attracted by the opposite sex and thus inclined to mate and have children. There are specifically human goods that are made manifest by our natural inclinations to live with others of our kind and to seek knowledge and avoid ignorance.
The goods revealed by such natural inclinations do not as such yield natural law precepts, as if "Eat, drink and be merry" were a precept of natural law. Rather, the natural inclinations reveal to us the constituents of our complete good and practical reason must then fashion guidelines for action which will become every more specific as the various goods made manifest by natural inclinations are pursued in more definite forms and in more particularized circumstances.
In its first description, natural law was said to be the peculiarly human participation in eternal law. We are not only governed by divine providence, we are so fashioned that we must govern ourselves. We do this by judging the fitting way to pursue the goods revealed by the natural inclinations. Knowledge is a good. Practical reason will see that the pell-mell pursuit of knowledge is destructive of the integral good of the person. So too the mindless pursuit of the pleasures of food and drink. Clearly, Do good and avoid evil is addressed by a rational agent to himself, and for him to do good is to do it in a reasonable way. The human good is a rational good, one judged to be worthy of pursuit. The recognition that we are naturally inclined to certain good is not the judgment that they are worthy of pursuit in just any old way. Each of these goods is comprehended by the integral good that is grasped in the very first principle, The good is to be done and pursued and evil avoided. The good of this natural inclination or that are specifications of, or constituents of, that comprehensive good. Pursuit of them will be judged fitting only if it does not jeopardize the comprehensive good.
The passage we have been analyzing is, by common consent, the single most important article Thomas devoted to the subject of natural law. It is paradoxically true that this discussion of that which is self-evidently true is very difficult to understand and quite different interpretations of it are offered by careful students of St. Thomas. This indicates that we should be careful not to equate the theory or discussion of natural law with the precepts of natural law. While everyone can be counted on to know the latter, the former is complicated and anything but self-evident. But what theorists seek to describe and explain is the fact that there are certain judgments as to what human beings ought to do or ought not do which only a fool could deny. Everyone knows that dealing unfairly with others is wrong -- at least when he himself is the victim.
Thomas Aquinas Selected Writings, selection 24.
How does the analogy between practical and speculative intellect enable Thomas to lay out the first precepts of natural law?