The natural law, then, is an unwritten law; but one that all people can know and which is binding on all persons everywhere. Thus, it is the sort of principle, as it were, that can serve as the sort of “thing” we intuitively take ethics to be: morally binding for all people. We can call it equivalently the Moral Law.[i] Law, however, is spoken of in several ways.[ii] The primary sense of law is that in which there is obligatory power. Thus, Aquinas says:
I answer that law is a rule and measure of acts that induces persons to act or refrain from acting, and the rule and measure of human acts is reason, which is the primary source of human acts. For it belongs to reason to order us to our end, which is the primary source of our prospective action, and the source in any kind of thing is the rule and measure of that kind of thing. And so we conclude that law belongs to reason[iii]… But the ultimate human end is happiness or blessedness. And so law especially needs to regard the order of blessedness… But law is primarily such because of its order to the common good. And so every precept regarding particular acts has the nature of law only because of its order to the common good. And so every law is ordered to the common good.[iv]
Here we find many of the core insights and principles of natural law. Of central importance is the understanding that law itself has a telos, and this is the common good. This is, however, only insofar as the common good is achieved; that is, only insofar as it makes people good. Thus, the telos of law is in fact virtue and the making of virtuous people. If a law fails in this regard then it is not, strictly speaking, law. Notice further that for Aquinas happiness is equivalent to blessedness. By this he does not mean what Aristotle refers to when he confers happiness to the blessed in the Ethics. Rather, Aquinas has a particular theologically informed end in mind, namely that of the visio beatitudo.[v] Here it seems clear that we have a prime example of deriving an ought from an is. For, given that it is the case that all men seek the final end whether they realise it or not, they should then become clear of the concept and reality behind their very being.[vi] If persons do not so act, in the least, to become clear concerning this reality, then they fail to be what they are at a basic level.
Natural law is law, then, because it stands in relation to other types of law. Aquinas distinguishes between three kinds of law: divine, natural, and human. Human law further has two kinds: what may be called the ius gentium, the law of nations or right of nations, and positive law. For our purposes these are currently irrelevant. The law that natural law stands in direct relation to is the eternal or divine law. We need not only consider this a strictly theological matter. In the Summa Aquinas does indeed make theological arguments but this is not to say that strictly philosophical arguments cannot be made. In part, this is what the Five Ways are designed to show. Thus, we can know via reason that God exists. Further, we know that He is the first cause and the actualisation of all being, and being personal has an intellect and will. Hence, without recourse to theology we have a concept of divine providence. Providence, however, simply means a governance of the whole cosmos according to the will of God; there is then governance by divine reason.[vii] The foundation of natural law is thus the subsistent reason of God within which all creatures, qua creatures, participate via natural inclinations. This, then, is the ultimate ontological foundation of natural law.[viii] Granted, there are tensions here but this is the consensus of the Thomistic tradition. Even stronger: as Maritain states, the goodness of the human will, which according to its function looks to natural law as its proximate measure, depends a fortiori on the eternal law. Eternal law is the emanation of divine reason, the source of the natural law, the natural inclinations of the human will, and the ultimate ontological cause of human nature and hence of the ontological foundation of ethical discourse.[ix]
Robert Gahl suggests another approach to understanding the necessity of eternal law and the activity of a divine being.[x] If we study the proper use of reason, as understood within the terms we have been discussing, then what it means to have human rationality is the ability to direct the goods sought to a single end. Indeed, Aristotle already made this abundantly clear in the Ethics.[xi] A human person is only fully rational when the due end is in sight and all else is ordered to it. To be otherwise is to be striving for full rationality, which is not immoral but rather something akin to continence. Such an ordering of ends would include the realisation that only an absolute good could be the sufficient end of all human desires. This, however, could only be understood to be a transcendent end, for reasons already stated above, and thus knowledge of this due end would include the understanding that such a transcendent good places moral injunctions upon us. This is very close indeed to the understanding of an eternal moral law. Thus, if we are allowed to have an eudemonistic ethics coupled with a natural teleology, then there must be an account of the rational determination of the human person towards the final end, which is the perfecting end of that nature.[xii] Thus, without recognition of the divine law and the final end there cannot be a coherent theory of natural law.[xiii] As we will see, even though this may be the case, non-theistic accounts can be given.
Natural law, then, is law given that it further meets the four criteria laid out for law.[xiv] Firstly it is an order of reason and, in this case, of human reason in concert with divine reason. Secondly it is ordered to the common good, since it is ordered to particular acts and preserves the final end, happiness, for the community at large. Thirdly natural law, by being a participation in divine law, belongs to all humanity and is law for them given that all things in the created order participate in the divine law. That is, in so far as we are creatures with reason and have intellects we participate in the divine law; thus, the natural law belongs to the whole human community. Also, thus, it is law if granted that God has providential care over all creation. Fourthly the natural law, as all law, is sufficiently promulgated and thus binding. The issue of promulgation falls under the epistemological aspect of natural law.
[i] Or if one prefers, as C.S. Lewis does, the Tao.
[ii] For example, there are the laws of which scientists speak, which should more accurately be called generalizations.
[iii] Aquinas, page 172. Summa Theologica I-II, Q. 90, A.1. emphasis added.
[iv] Ibid, 173. Summa Theologica I-II, Q. 90, A. 2. emphasis added.
[v] See Summa Theologica I-II, Q. 2, A. 8, C. The concept behind this is simple: no created good, or good within the created order of the universe, can satisfy man’s desire for the good. The object of the human will is the universal good itself, just as the object of the intellect is the universal truth itself. Nothing short of this will fulfill us. This follows from the formal account Aquinas gives of action: action is directed towards some good. Thus, human desires fall under the order of goodness. Further, given these considerations, the only good that will fully quiet the restless human heart is the perfect good. This cannot be any created good since, simply enough, every created thing and creature has a participated goodness. Bear in mind here the convertibility thesis in regards to the transcendentals. Only God alone possess perfect, non-participatory goodness because only God alone is being as such and receives being from nothing else. Hence, only God can fulfill our desires and be both the formal and actual perfective end of human nature. See McInerny chapter II for further discussion.
[vi] It is true, granted, that the vast majority of mankind is entirely unaware of what the true end is; a moral theory should also ultimately give an account as to why this is the case. For the Christian, much of this explanatory work, although certainly not all, may be accomplished via the concept of sin and fallen-ness. This is one more reason why humanity needs the virtues. Through the virtues there is made possible a heroic overcoming of fallen nature, albeit not in simpliciter. For someone thinking along the terms of Aquinas, divine grace is a necessary ingredient.
[vii] Thus far I do not think that anything which I have claimed is incompatible with either of the two great branches of Catholicism, either East or West. It shall be my attempt to offer an understanding that is conducive to the theologies of both.
[viii] The proximate foundation is the shared commonality of the human essence.
[ix] This is not, however, cause for us to fall into a form of divine command theory. If we remain realists about essences, and not nominalists, then we avoid this unpleasant alternative.
[x] Gahl, Robert A, Jr. “Who Made the Law? God, Ethics, and the Law of Nature.” Article in Virtue’s End, edited by Fulvio Di Blasi et al. South Bend, Indiana: St. Augustine’s Press, 2008, (120-123).
[xi] Although, eminent philosophers such as Terence Irwin fail to see it this way. See Richard Kraut’s Aristotle on the Human Good for an excellent treatment of this issue.
[xii] Here we may quite easily, as Gahl suggests quite correctly, insert a philosophical anthropology of original sin or fall. The determination of the human will towards the final end has been damaged; as Anselm stated, there is no longer rectitude. And so, a conversion to the final end would indeed involve an ordo amoris, through an act of the will. Yet, we cannot love what we do not know, thus there is an imperative to know what the final end of man is. This draws us very close to a doctrine of remuneration, since if we truly do understand that the final end is the highest good and we pursue it then possession of that highest good is worth giving up anything for it. Here the virtues of courage and hope will sustain the person in the searching, and since this is intrinsically possible, in principle, for all persons, all persons have the ability to come to a knowledge of their end. “Seek and you will find,” as it was said, and sanctifying grace will follow. This, I hope, will serve to assuage many of the fears of the more theologically inclined readers of this paper. Further, I trust that it makes some headway in showing to those not so inclined that theistic beliefs are not simply made up.
[xiii] Gahl, 123.
[xiv] See Summa Theologica I-II, Q. 90-91.