From the Treasure Chest: A Primer on Natural Law

My friend John C.H. Wu was a highly regarded jurist and professor of law. He had a close friendship with Justice Oliver Wendell Holmes of the U.S. Supreme Court. It turns out that one of the reasons he converted to the Catholic Faith was that the Church embraces what is know as the Natural Law. The same goes for his friend Dom Lou Tseng-Tsiang.

So in the interest of learning what exactly this means for regular folks, without enduring a semester of law school, I scouted Google Books and found another gem of a book by another long dead Jesuit. Entitled The Relations of the Church to Society, and authored by Edmund J. O’Reilly, SJ, the very first chapter is an essay on the Natural Law.

There will not be a pop quiz on this, but it will be on the mid-term as well as on the final exam. Fr. Ed has the floor,


The title I have prefixed to these pages is rather formidable, and may suggest the idea of a ponderous volume, or at least of considerable prolixity. But, though the subject is vast, I am not about to treat it on a large scale. I will content myself with briefly stating, and very moderately developing, a few principles, necessary at all times to be well understood, and never more so than at present. I will speak throughout as a Catholic addressing Catholics. I should not be afraid or ashamed to say the same things to non-Catholics, and I shall not be sorry to have some of them among my readers; for it is well that they should know what we really hold, and many of their number would think it not so unreasonable after all. But they cannot be expected to accept without a good deal of argument all that I may assume in dealing with Catholics.

It may be asked why I should tell Catholics what they already admit. I reply that many Catholics—otherwise well-educated men—form confused notions, and even fall into serious mistakes, regarding various points of Catholic doctrine. They fail to realize all that is contained in the truths which they hold, and often unwittingly entertain opinions which are far from being sound. They, at times, culpably or inculpably, shut their eyes to truths that either form part of the Catholic faith, or are closely bound up with it.

They occasionally need to be put in mind that if our holy religion is to be received as Divine, it is to be received in its integrity, and with all those conclusions which cannot be consistently denied to flow from its dogmas. Once revelation—Christian, Catholic revelation—is admitted, we must treat it in the same way as we treat natural knowledge, not evading obvious consequences which cannot be questioned without virtually questioning premises that we profess to receive as altogether certain. Revealed truths are truths in the same sense as other truths, and demand, like other truths, that in embracing them we should embrace whatever is essentially connected with them.

Formularies are necessary, that the chief doctrines may be clearly set forth. But formularies, especially those which are incomplete, and even those which are complete for their purpose, do not fix boundaries within which we can intrench ourselves and say: I admit all that is stated here in so many words; but outside of these terms I will reject what I please. Much less can we frame a formulary for ourselves, and select the dogmas it is to comprise, while we set aside others equally entitled to a place.

As I have used the word dogma, I may take occasion to observe that the tenets of a Catholic—the obligatory tenets of a Catholic—are not confined, nor does any Catholic who is sound and well instructed conceive them to be confined, to what are strictly called dogmas of faith. This will be brought out more clearly as we proceed, but it is no harm to make the observation here in passing.

I will not expend any more of my limited space on prefatory remarks; but will proceed at once to ask and answer a fundamental, though apparently simple and elementary, question.

What is a Religion? More definitely still, what is the Catholic Religion? It is, I reply, the sum of all the truths which God has proposed for our belief, of all the laws He has enacted for our observance, and of all the external means of obtaining grace He has provided for us on earth. The Catholic Religion is nothing less than all this, otherwise it would not be, as it assuredly is, an adequate way of salvation. Were it not so, a Catholic might live perfectly up to his Religion and lose his soul.

In the Catholic Religion there are three great elements, the dogmatic, the moral, and the sacramental; to say nothing at this stage concerning a fourth, namely, the administrative or governmental, which may be referred in some sort to the sacramental, but may also be distinguished from it, as I prefer doing. These three elements are interwoven with each other. For there are dogmas which regard morals as their object, and there are dogmas which regard sacraments and other helps to sanctification as their object; and, on the other hand, the belief of dogmas and the use of sacraments are matter of moral obligation.

My present concern is more particularly with morals, as such—the moral element, as such—and with the Divine Laws which command or forbid a variety of actions. Under the name of actions I include words and thoughts, which are in reality so many actions.

There are two great kinds or classes of Divine Laws, namely, the Natural and the Positive. Natural Law is that which is demanded by the nature of things, and has been accordingly enacted by the Author of Nature. Positive Law is that which He has freely superadded for wise purposes. Either class may be spoken of in the singular or in the plural number, may be called Law or Laws. The first class is more generally spoken of in the singular than it is in the plural number, and certainly oftener spoken of in the singular number than the second.

The end I have proposed to myself requires that I should dwell especially on Natural Law, and develop the notion of it I have already given in a single short sentence. I take for granted, in addressing Catholics, that there is such a thing as morality of human actions, distinct from their mere utility, and not universally or exclusively depending on it. Among the pestilential and degrading doctrines disseminated by many modern infidels is the denial of this truth. It would be going out of my way to refute them here.

There are various degrees in the doctrine I have alluded to, some worse than others: but the whole principle of such systems is false. I do not mean, of course, to deny that morality often coincides with utility, and that morality is closely connected with the interests of men, their temporal as well as their eternal interests. But that utility is the whole origin and basis of what is called moral goodness, and of its distinction from what is called moral evil, is a thoroughly unchristian theory.

Natural Law is based on the nature and relations of things, principally on the nature of God and His relation to man, on the nature of man and his relation to God and to his fellow-men, and to himself, so far as any being can be said to bear relation to itself. This Law is a real Law, as truly a Law as any other; a Law indeed called for by the nature of things, and which the Divine attributes require should be made in the supposition of man’s existence. It is not made by nature, for a law must come from a superior, and nature is not superior to itself; but it is made to satisfy a requirement of nature.

The Legislator is God; the primary medium by which He promulgates this Law, the herald that proclaims it, is man’s reason, whose dictates declare its existence and enactments. For reason, properly applied, recognizes the requirement I have mentioned; knowledge of the requirement brings along with it knowledge of the existence of the Law, since even reason teaches that God cannot neglect such a demand. Further, knowledge of the details of the requirement includes knowledge of the details of the Law. The more prominent of these details constitute the principles of the Natural Law, whence the rest are deduced.

The most remote conclusions, however, when reached are as binding as the principles. But the limited character of our reason, and a variety of unfavorable circumstances stand in the way of our arriving at all these conclusions. We are liable to ignorance and error regarding them. This ignorance and this error, when invincible, that is to say, unavoidable, and consequently inculpable, excuse us from the practical obligation of those parts of the Natural Law that are not sufficiently presented to us, though they still continue truly parts of the Law. Some of the wisest men, and those best versed in these matters, have differed and do differ on remote conclusions or precepts of the Natural Law, and indeed occasionally on some that are not so very remote.

The Natural Law is the most comprehensive of all laws. Every conceivable free action, with every conceivable variety of circumstances, is definitely provided for by the Natural Law. It is either commanded, or forbidden, or approved, or allowed. It may be said, indeed, that the mere allowance or permission of an act is not an affirmative function of the Natural Law, and about this I will not dispute. What I mean to convey is, that no act escapes the operation of this Law on account of its complexity, that every variety of circumstances that has any moral aspect is dealt with by it. Every possible free action is either morally good, or morally bad, or morally indifferent.

Whether a perfectly deliberate action actually done by this or that man, taken in its integrity with its end and circumstances, can be indifferent, that is to say, neither good nor bad morally, is a question controverted in philosophy and theology, and which I shall not discuss. It is quite certain that there are innumerable possible actions, which considered abstractedly and without reference to the intention of the agent, are indifferent. If I am asked, for instance, whether walking, or riding, or hunting, or a thousand other things, are good or bad, I cannot say that they are either. Although in strictness indifference is not a species or kind of morality, like goodness or badness, we may for convenience take it as such, in order to classify all free actions under the respect of morality; and there is some foundation for so taking it, since an action by being indifferent is morally allowable.

No action is beyond the reach of the Natural Law, even though that action belong to the supernatural order. For example, if the reception of a Christian Sacrament, in circumstances in which this reception is not commanded by any positive law of God or the Church, be a necessary means to guard against sin, the Natural Law steps in and commands it. That Law has nothing to do with the institution of Sacraments; but finding them instituted, it will take them in and impose obligations regarding them. Such intervention is qualified as hypothetical Natural Law; but it is not less truly a part of the Natural Law. If Natural Law could be written out, the code would specify the moral character of every possible human action. There is in it no such thing as a casus omissus.

There is no such thing as an exception to any part of it, though we are compelled to talk of exceptions, because for convenience we express some portions of this Law in certain brief forms. We say, for example, that men are forbidden to kill one another. Yet, from this prohibition we have to except the cases of just war, of the capital punishment of malefactors by public authority, of self-defense against an unjust aggressor. But the Law, considered in itself, as it is, pronounces on each action as affected by the circumstances in which it could be performed.

This comprehensiveness of Natural Law leaves still abundant room for other Laws, Divine and human. Many acts which the Natural Law approves or allows, it does not command. Now a competent authority may prescribe or forbid an act which is neither prescribed nor forbidden by Natural Law left to itself. God himself may prescribe or forbid such an act by a positive law; so may the Church or the State. And the act thus prescribed or forbidden will become obligatory on the one hand or wrong on the other, in place of being merely good or indifferent.

Further, once such additional law is made, the Natural Law will take it into account, and insist on its observance. We may say with perfect truth that whatever is commanded or prohibited by any positive Law, Divine or human, is consequently commanded or forbidden by the Natural Law, imposing as it does the obligation of obeying legitimate authority—legitimate as to its existence and as to its exercise.

I have said that no action is beyond the reach of the Natural Law. This obviously holds good with regard to all classes of persons, whatever be their position, whatever be their dignity, whatever be their authority. This holds good for sovereigns and subjects. This holds good, too, with regard to all classes of actions, whether they be of a private or of an official character. This holds good for the combined actions of many persons. Every individual is amenable to Natural Law in all that he does, either separately or in conjunction with others.

This statement may seem superfluous, since no Christian can be ignorant or doubtful of its truth. But it is not superfluous; for even though not controverted, there is need of bearing it in mind, and not neglecting to apply it when occasion requires. Besides, there is often a latent tendency in our minds to distinguish unduly public from private actions, as if the magnitude of a proceeding withdrew it from the operation of the rules of morality. Those who would shudder at the thought of an isolated murder are but little startled by the wholesale murder involved in unjust warfare.

As I have been speaking of combined action, I may observe that not only are certain courses of public conduct morally bad, and imputable as sins to those who participate in them; but other courses of public conduct are commanded and obligatory on communities and nations—with this difference, that every one can avoid cooperating in what is evil, but every one cannot insure the performance of what is due on the part of a large body of which he is a member; and there are many who individually can contribute little or nothing towards the discharge of such public duties. But those who are invested with the requisite power are bound to use it for the purpose.

It is now time to consider the relations which subsist between Natural Law and Revelation. If there never had been any supernatural revelation, the Natural Law would have existed, and the fact of supernatural revelation does not put an end to Natural Law, nor diminish its binding force. If we imagine a revelation that would take no notice of Natural Law, the latter would still hold its ground.

But the revelation we have had is very far from not noticing Natural Law. The Old and New Testaments reproduce and additionally promulgate many of its precepts, and in a compendious way the whole of them. The ten commandments are a summary of them all, with but very little addition of positive Law, namely, in the third the setting aside of one particular day of each week for a special worship of God. The main substance of the third commandment, namely, that God is to be worshipped, and reasonable times appointed for the fulfillment of this duty, is part of the Natural Law. In the New Testament Our Lord and His Apostles inculcate sometimes general principles of the Natural Law, sometimes particular precepts belonging to it.

It would be easy to give a long list of moral propositions recorded in the Gospels and Epistles, and which are so many statements of Natural Law. There is no precept of Natural Law that is not contained in and reducible to some of these propositions, and thus made part of the Evangelical Law—of the Christian Religion—of the Catholic Religion. So surely as any action is approved, commanded or forbidden by the Natural Law, it is approved, commanded or forbidden respectively by the Evangelical Law—by the Catholic Religion. A controversy may arise as to whether a particular action is thus approved, commanded or forbidden by Natural Law; and I have already said that such controversies are maintained by the wisest and best qualified men ranged on either side—innocently, inculpably, nay, laudably maintained.

But both parties are quite ready to admit that whichever of the two opposite propositions is true as to Natural Law, is equally true as to Gospel Law. Take, for example, the fifth commandment, “Thou shalt not kill.” This is a precept of Natural Law, additionally promulgated in the Mosaic tables and in the Gospel. Catholic theologians, though pretty generally agreed as to the lawfulness of killing a private unjust aggressor in defense of life, are not equally agreed as to the lawfulness of killing a robber for the sake of preserving property ever so valuable. If those who deny the right are correct in their opinion, the homicide of which there is question falls within the fifth commandment, as Natural and Evangelical Law, and is at variance with the morality of the Catholic Religion, though persons acting in good faith on the opposite view may escape blame in the eyes of God. They are merely mistaken on an obscure point of morality.

What I chiefly wish to insist on is, that all true developments of briefly expressed precepts, whether actually reached by us or not, are as really parts of the Natural and Evangelical Laws as the briefly expressed precepts themselves: that these briefly expressed precepts stand for, and represent, all that is contained under them. Thus, in the example, every case of man-killing which is really forbidden by Natural Law is as much included as any other under the form “Thou shalt not kill,” taken as part of the Natural and, at the same time, of the Gospel Law.

This is true of the Gospel Law, even where Revelation affords no sufficient proof that a particular case is included; for the Gospel Law commands whatever is really comprehended in the Natural precept, which it records and confirms. Hence, if reason satisfactorily shows that the case is comprehended in a Natural precept, it thereby shows that the same case is comprehended in the Gospel Law. There is no question here of believing with Divine Faith that this or that particular act is prescribed or prohibited, but merely of the fact of its being so prescribed or prohibited by Gospel Law.

It is the common doctrine of theologians that all the merely moral legislation of Christianity, as distinguished from what more immediately regards faith and the sacraments, is coincident with, and declaratory of, Natural Law: that no moral law has been added, new or more extended as to its matter, that no natural acts have been commanded or prohibited, which were not respectively commanded or prohibited before by Natural Law. It does not follow from this that there is not an additional obligation imposed by the Law of Christ, formally prescribing over again the same things which were prescribed before.

It may be said reasonably enough that we are more bound by two Divine Laws than by one only; that the obligation is intensified, not, however, so as that any thing has become a mortal sin which was not already such. On the other hand, any similar obligation which the Law of Moses may have added to that of the Natural Law, by the explicit repetition of its precepts, appears to have passed away with the Jewish dispensation. Hence the ten commandments, for instance, recorded in Exodus and Deuteronomy, bind us as Natural Law and as confirmed by Christ, not as imposed through Moses. On this point theologians are not agreed.

I began by asking and undertaking to answer this question: What is the Catholic Religion? My answer was, that the Catholic Religion is the sum of all the truths which God has proposed for our belief, of all the laws He has enacted for our observance, and of all the external means of obtaining grace He has provided for us on earth. I added that in the Catholic Religion there are three great elements, the dogmatic, the moral, the sacramental, passing by for the moment, and only the moment, another, namely the administrative or governmental. I have dwelt at some little length on the moral element, and especially on the Natural Law considered in itself, and as republished and reimposed by Christ our Lord and His Apostles. I have no occasion at present to develop the dogmatic and sacramental elements. I proceed now to another question to be asked and answered, namely: What is the Catholic Church?

That is covered in Chapter Two. No sweat. Other resources:
St. Thomas Aquinas’ thoughts on Natural Law
Cicero and the Natural Law