Aquinas. Edward Feser

Chapter 5 Ethics 

Throughout this book, I have emphasized how crucial a grasp of Aquinas’s general metaphysics is to a proper understanding of his views in specific philosophical sub-disciplines such as the philosophy of religion and the philosophy of mind. It is no less crucial to understanding his views in that field which to contemporary philosophers might seem the furthest removed from metaphysics, namely ethics. Many philosophers today would heartily endorse Hilary Putnam’s recent advocacy of what he calls “ethics without ontology.” John Rawls famously defended a conception of justice he described as “political not metaphysical.” It is widely assumed that the analysis and justification of fundamental moral claims can be conducted without reference to at least the more contentious issues of metaphysics. Nothing could be further from the spirit of Aquinas, for whom natural law (as his conception of morality is famously known) is “natural” precisely because it derives from human nature, conceived of in Aristotelian essentialist terms. To be sure, recent decades have seen a tendency to try to reinterpret Aquinas’s ethics in a way that divorces it from his now highly controversial essentialism. The most influential version of this approach is the “new natural law theory” of Germain Grisez and John Finnis. For Aquinas himself, however, and for Thomism historically, such a flight from Aristotelian metaphysics is neither necessary nor desirable. The truth about human beings can only be seen in light of the truth about the world in general. Aristotelian essentialism is not merely an abstract metaphysics but (as Henry Veatch has described it) an “ontology of morals.” 

The good 

Now philosophers like Kai Nielsen and D. J. O’Connor have objected that Aquinas’s metaphysical approach to ethics is a non-starter, on the grounds that it ignores the “fact/value distinction.” For as Hume famously argued, conclusions about what ought to be done (which are statements about “value”) cannot be inferred from premises concerning what is the case (statements of “fact”). To assume otherwise, it is claimed, is to commit the “naturalistic fallacy.” The hope of side-stepping this objection to Aquinas is part of the reason why Grisez and Finnis have sought to develop a “new” natural law theory which, unlike the traditional version, does not seek to ground morality in factual premises concerning the metaphysics of human nature. 

From the traditional Thomistic point of view, however, there simply is no “fact/value distinction” in the first place. More precisely, there is no such thing as a purely “factual” description of reality utterly divorced from “value,” for “value” is built into the structure of the “facts” from the get-go. A gap between “fact” and “value” could exist only given a mechanisticcum-nominalistic understanding of nature of the sort commonly taken for granted by modern philosophers, on which the world is devoid of any objective essences or natural ends. No such gap, and thus no “fallacy” of inferring normative conclusions from “purely factual” premises, can exist given an Aristotelian–Thomistic essentialist and teleological conception of the world. “Value” is a highly misleading term in any case, and subtly begs the question against critics of the “fact/value distinction” by insinuating that morality is purely subjective, insofar as “value” seems to presuppose someone doing the valuing. Aristotelians and Thomists (and other classical philosophers such as Platonists) tend to speak, not of “value,” but of “the good,” which on their account is entirely objective. 

We have already seen how this is so, in our discussion of the convertibility of the transcendentals being and good in chapter 2. To return to a simple example from that discussion, it is of the essence of a triangle to be a closed plane figure with three straight sides, and anything with this essence must have a number of properties, such as having angles adding up to 180 degrees. These are straightforward objective facts, and remain so even though there are triangles which fail perfectly to match this description. A triangle drawn hastily on the cracked plastic seat of a moving bus might fail to have sides that are perfectly straight, and thus its angles will add up to something other than 180 degrees. Even a triangle drawn slowly and carefully on art paper with a straight edge and a Rapidograph pen will contain subtle flaws. Still, the latter will more perfectly approximate the essence of triangularity than the former will. It will be a better triangle than the former one. Indeed, we would naturally call the former a bad triangle and the latter a good one. This judgment would be completely objective; it would be silly to suggest that it reflects nothing more than a subjective preference for triangles with angles adding up to 180 degrees. It would be equally silly to suggest that we have somehow committed a fallacy in making a “value” judgment about the badness of the triangle drawn on the bus seat on the basis of the “facts” about the essence of triangularity. Given that essence, the “value judgment” in question obviously follows necessarily. This example illustrates how an entity can count as an instance of a certain kind of thing even if it fails perfectly to instantiate the essence of that kind of thing; a badly drawn triangle is not a non-triangle but a defective triangle. It also illustrates how there can be a perfectly objective, factual standard of goodness and badness, better and worse. To be sure, the standard in question in the current example is not a standard of moral goodness. But from an Aristotelian–Thomistic point of view, it illustrates a general notion of goodness of which moral goodness is a special case. 

Livings things provide examples that bring us closer to a distinctively moral conception of goodness, as has been noted by several contemporary philosophers who, though not Thomists, have defended a kind of neoAristotelian position in ethics. For instance, Philippa Foot, following Michael Thompson, has noted how living things can only adequately be described in terms of what Thompson calls “Aristotelian categoricals” of a form such as S’s are F, where S refers to a species and F to something predicated of the species. “Rabbits are herbivores,” “Cats are four legged,” and “Human beings have thirty-two teeth” would be instances of this general form. Note that such propositions cannot be adequately represented as either existential or universal propositions, as these are typically understood by modern logicians. “Cats are four legged,” for instance, is not saying “There is at least one cat that is four legged”; it is obviously meant instead as a statement about cats in general. But neither is it saying “For everything that is a cat, it is four legged,” since the occasional cat may be missing a leg due to injury or genetic defect. Aristotelian categoricals convey a norm, much like the description given above of what counts as a triangle. Any particular living thing can only be described as an instance of a species, and a species itself can only be described in terms of Aristotelian categoricals stating at least its general characteristics. If a particular S happens not to be F – if for example a certain cat is missing a leg – that does not show that S’s are not F after all, but rather that this particular S is a defective instance of an S. 

In living things the sort of norm in question is, as Foot also notes, inextricably tied to the notion of teleology; as Aquinas puts it, “all who rightly define good put in its notion something about its status as an end” (QDV 21.1). There are certain ends that any organism must realize in order to flourish as the kind of organism it is, ends concerning activities like selfmaintenance, development, reproduction, the rearing of young, and so forth; and these ends entail a standard of goodness. Hence an oak that develops long and deep roots is to that extent a good oak and one that develops weak roots is to that extent bad and defective; a lioness which nurtures her young is to that extent a good lioness and one that fails to do so is to that extent bad and defective; and so on. As with the triangle example, it would be silly to pretend that these judgments of goodness and badness are in any way subjective or reflective of mere human preferences, or that the inferences leading to them commit a “naturalistic fallacy.” For they simply follow from the objective facts about what counts as a flourishing or sickly instance of the biological kind or nature in question, and in particular from an organism’s realization or failure to realize the ends set for it by its nature. The facts in question are, as it were, inherently laden with “value” from the start. Or, to use Foot’s more traditional (and less misleading) language, the goodness a flourishing instance of a natural kind exhibits is “natural goodness” – the goodness is there in the nature of things, and not in our subjective “value” judgments about them. 

What is true of animals in general is true of human beings. Like the other, non-rational animals, we have various ends inherent in our nature, and these determine what is good for us. In particular, Aquinas tells us, “all those things to which man has a natural inclination, are naturally apprehended by reason as being good, and consequently as objects of pursuit, and their contraries as evil, and objects of avoidance” (ST I-II.94.2, emphasis added). It is important not to misunderstand the force of Aquinas’s expression “natural inclination” here. By “inclination” he does not necessarily mean something consciously desired, and by “natural” he doesn’t mean something psychologically deep-seated, or even, necessarily, something genetically determined. What he has in mind are rather the final causes or natural teleology of our various capacities. For this reason, Anthony Lisska has suggested translating Aquinas’s inclinatio as “disposition.” While this has its advantages, even it fails to make it clear that Aquinas is not interested in just any dispositions we might contingently happen to have, but rather in those that reflect nature’s purposes for us. Of course, there is often a close correlation between what nature intends and what we desire. Nature wants us to eat so that we’ll stay alive, and sure enough we tend to want to eat. Given that we are social animals, nature intends for us to avoid harming others, and for the most part we do want to avoid this. Given that we need to reproduce ourselves, nature intends for us to have sexual relations, and obviously most people are quite happy to do so. At the same time, there are people (such as anorexics and bulimics) who form very strong desires not to eat what they need to eat in order to survive and thrive; and at the other extreme there are people whose desire for food is excessive. Some people are not only occasionally prone to harm others, but are positively misanthropic or sociopathic. And where sex is concerned, people often strongly desire to indulge in behaviors (masturbation, contraception, homosexual acts, and so forth) that are in Aquinas’s view contrary to nature’s purposes insofar as they do not have a natural tendency to result in procreation. Desires are nature’s way of prodding us to do what is good for us, but like everything else in the natural order, they are subject to various imperfections and distortions. Hence, though in general and for the most part our desires match up with nature’s purposes, this is not true in every single case. Habituated vice, peer pressure, irrationality, mental illness, and the like can often deform our subjective desires so that they turn us away from what nature intends, and thus from what is good for us. Genetic defect might do the same; just as it causes deformities like clubfoot and polydactyly, so too might it generate psychological and behavioral deformities as well. 

Here as elsewhere, it is crucial in understanding Aquinas’s views that one keeps his general metaphysical positions always in mind. “Natural” for Aquinas does not mean merely “statistically common,” “in accordance with the laws of physics,” “having a genetic basis,” or any other of the readings that a mechanistic view of nature might suggest. It has instead to do with the final causes inherent in a thing by virtue of its essence, and which it possesses whether or not it ever realizes them or consciously wants to realize them. What is genuinely good for someone, accordingly, may in principle be something he or she does not want, like children who refuse to eat their vegetables, or an addict convinced that it would be bad to stop taking drugs. For Aquinas, knowing what is truly good for us requires taking an external, objective, “third-person” point of view on ourselves rather than a subjective “first-person” view; it is a matter of determining what fulfills our nature, not our contingent desires. The good in question has moral significance for us because, unlike other animals, we are capable of intellectually grasping what is good and freely choosing whether or not to pursue it. 

Aquinas identifies three general categories of goods inherent in our nature. First are those we share in common with all living things, such as the preservation of our existence. Second are those common to animals specifically, such as sexual intercourse and the child-rearing activities that naturally follow upon it. Third are those peculiar to us as rational animals, such as “to know the truth about God, and to live in society,” “to shun ignorance,” and “to avoid offending those among whom one has to live” (ST I-II.94.2). These goods are ordered in a hierarchy corresponding to the hierarchy of living things (i.e. those with vegetative, sensory, and rational souls respectively). The higher goods presuppose the lower ones; for example, one cannot pursue truth if one is not able to conserve oneself in existence. But the lower goods are subordinate to the higher ones in the sense that they exist for the sake of the higher ones. The point of fulfilling the vegetative and sensory aspects of our nature is, ultimately, to allow us to fulfill the defining rational aspect of our nature. 

What specifically will fulfill that nature? Or in other words, in what does the good for us, and thus our well-being or happiness, ultimately consist? It cannot be wealth, because wealth exists only for the sake of something else which we might acquire with it (ST I-II.2.1). It cannot be honor, because honor accrues to someone only as a consequence of realizing some good, and thus cannot itself be an ultimate good (ST I-II.2.2). For similar reasons, it cannot be fame or glory either, which are in any case often achieved for things that are not really good in the first place (ST I-II.2.3). Nor can it be power, for power is a means rather than an end and might be used to bring about evil rather than genuine good (ST I-II.2.4). It cannot be pleasure, because pleasure is also a consequence of realizing a good rather than the realization of a good itself; even less likely is it to be bodily pleasure specifically, since the body exists for the sake of the soul, which is immaterial (ST I-II.2.6). For the same reason, it cannot consist of any bodily good of any other sort (ST I-II.2.5). But neither can even it be a good of the soul, since the soul, as a created thing, exists for the sake of something else (i.e. that which creates it) (ST I-II.2.7). Obviously, then, it cannot be found in any created thing whatsoever; our ultimate end could only possibly be something “which lulls the appetite altogether,” beyond which nothing more could be desired, and thus something absolutely perfect (ST I-II.2.8). And “this is to be found,” Aquinas concludes, “not in any creature, but in God alone … Wherefore God alone can satisfy the will of man … God alone constitutes man’s happiness” (ST I-II.2.8). That is not to deny that wealth, honor, fame, power, pleasure, and the goods of body and soul have their place; they cannot fail to do so given that we are the kinds of creatures that we are. Aquinas’s point is that it is impossible for them to be the highest or ultimate good for us, that to which every other good is subordinated. God alone can be that. 

In Aquinas’s view, what is good for us is, as I have said, something that remains good for us even if for some reason we do not recognize it as good. What is good for us is necessarily good for us because it follows from our nature. As such, even God couldn’t change it, any more than he could make two and two equal to five. Here we see one important consequence of Aquinas’s view that the intellect is metaphysically prior to the will, in the sense that (as we saw in the last chapter) will derives from intellect rather than vice versa. The divine intellect knows the natures of things and the divine will creates in accordance with this knowledge. To be sure, the natures in question exist at first only as ideas in the divine mind itself; in this sense they are, like everything else, dependent on God. Still, in creating the things that are to have these natures, the divine will only ever creates in light of the divine ideas and never in a way that conflicts with what is possible given the content of those ideas. Aquinas’s position is thus very far from the sort of “divine command ethics” according to which what is good is good merely because God wills it, so that absolutely anything (including torturing babies for fun, say) could have been good for us had he willed us to do it. This sort of view was famously taken by William of Ockham (c. 1287–1347), according to whom God could even have willed for us to hate him, in which case that is what would have been good for us. Such a position naturally follows from the “voluntarism” or emphasis on will over intellect associated with Ockham and John Duns Scotus (c. 1266–1308), which is one of the key features distinguishing their brands of Scholasticism from Thomism. 

This difference between Aquinas and the voluntarists is related to the reasons for which Aquinas’s position is, as we saw in chapter 3, immune to the famous “Euthyphro objection” to religiously based systems of ethics. The objection, it will be recalled, is in the form of a dilemma: either God wills something because it is good or it is good because he wills it; but if the former is true, then, contrary to theism, there will be something that exists independently of God (namely the standard of goodness he abides by in willing us to do something), and if the latter is true, then if God had willed us to torture babies for fun (say) then that would have been good, which seems obviously absurd. Ockham essentially takes the second horn of the dilemma, but for Aquinas the dilemma is a false one. What is good for us is good because of our nature and not because of some arbitrary divine command, and God only ever wills for us to do what is consistent with our nature. But that doesn’t make the standard according to which he wills something existing independently of him, because what determines that standard are the ideas existing in the divine mind. Thus there is a third option between the two set out by the Euthyphro dilemma, and it is one that is neither inconsistent with our basic moral intuitions nor incompatible with the claims of theism.

Natural law

It is but a few short steps from “natural goodness” (as Foot calls it) to Aquinas’s conception of natural law. The first principle of natural law, as Aquinas famously held, is that “good is to be done and pursued, and evil is to be avoided. All other precepts of the natural law are based upon this,” where the content of those precepts is determined by the goods falling under the three main categories mentioned above (ST I-II.94.2). That “good is to be done” and so on might seem at first glance to be a difficult claim to justify, and certainly not a very promising candidate for a first principle. For isn’t the question “Why should we be good?” precisely (part of) what any moral theory ought to answer? And isn’t this question notoriously hard to answer to the satisfaction of moral skeptics? Properly understood, however, Aquinas’s principle is not only not difficult to justify, but even seems obviously correct. He is not saying that it is just self-evident that we ought to be morally good. Rather, he is saying that it is self-evident that whenever we act, we pursue something that we take to be good in some way and/or avoid what we take in some way to be evil or bad. And that seems clearly right. Even someone who does something he believes to be morally bad does so only because he is seeking something he regards as good in the sense of worth pursuing. Hence the mugger who admits that robbery is evil nevertheless takes his victim’s wallet because he thinks it would be good to have money to pay for his drugs; hence the drug addict who regards his habit as wrong and degrading nevertheless thinks it would be good to satisfy his craving and bad to suffer the unpleasantness of not satisfying it. Of course, these claims are true only on a very thin sense of “good,” but that is exactly the sense Aquinas intends. Acceptance of Aquinas’s general metaphysics is not necessary in order to see that this first principle is correct; it is supposed to be self-evident. But that metaphysics is meant to help us understand why it is correct. Like every other natural phenomenon, practical reason has a natural end or goal towards which it is ordered, and that end or goal is just whatever the intellect perceives to be good or worth pursuing. This claim too seems obvious, at least if one accepts Aquinas’s Aristotelian metaphysics. And it brings us to the threshold of a further conclusion that does have real moral significance. Given what was said earlier, human beings, like everything else in the world, have various capacities and ends the fulfillment of which is good for them and the frustrating of which is bad, as a matter of objective fact. A rational intellect apprised of the facts will therefore perceive that it is good to realize these ends and bad to frustrate them. It follows, then, that a rational person will pursue the realization of these ends and avoid their frustration. In short, Aquinas’s position is essentially this: practical reason is directed by nature towards the pursuit of what the intellect perceives as good; what is in fact good is the realization or fulfillment of the various ends inherent in human nature; and thus a rational person will perceive this and, accordingly, direct his or her actions towards the realization or fulfillment of those ends. In this sense, good action is just that which is “in accord with reason” (ST III.21.1; cf. ST I-II.90.1), and the moral skeptic’s question “Why should I do what is good?” has an obvious answer: because to be rational just is (in part) to do what is good, to fulfill the ends set for us by nature. Natural law ethics as a body of substantive moral theory is the formulation of general moral principles on the basis of an analysis of these various human capacities and ends and the systematic working out of their implications. So, to take just one example, when we consider that human beings have intellects and that the natural end or function of the intellect is to grasp the truth about things, it follows that it is good for us – it fulfills our nature – to pursue truth and avoid error. Consequently, a rational person apprised of the facts about human nature will see that this is what is good for us and thus strive to attain truth and to avoid error. And so on for other natural human capacities. Now things are bound to get more complicated than that summary perhaps lets on. Various qualifications and complications would need to be spelled out as the natural human capacities and ends are examined in detail, and not every principle of morality that follows from this analysis will necessarily be as simple and straightforward as “Pursue truth and avoid error.” Particularly controversial among contemporary readers will be Aquinas’s application of his method to questions of sexual morality (SCG III.122–126; ST II-II.151–154). Famously, he holds that the only sexual acts that can be morally justified are those having an inherent tendency towards procreation, and only when performed within marriage. The reason is that the natural end of sex is procreation, and because this includes not merely the generation of new human beings but also their upbringing, moral training and the like, which is a long-term project involving (in the normal case, for Aquinas) many children, a stable family unit is required in order for this end to be realized. Any other sexual behavior involves turning our natural capacities away from the end set for them by nature, and thus in Aquinas’s view cannot possibly be good for us or rational. This rules out, among other things, masturbation, contraception, fornication, adultery, and homosexual acts. This is a large topic which cannot be treated adequately here. (I discuss Aquinas’s approach to sexual morality in detail in my book The Last Superstition.) But this much is enough to provide at least a general idea of how his natural law approach to ethics determines the specific content of our moral obligations. The method should be clear enough, whether or not one agrees with Aquinas’s application of that method in any particular case. What has been said also suffices to give us a sense of the grounds of moral obligation, that which makes it the case that moral imperatives have categorical rather than merely hypothetical force (to use the distinction made famous by Kant). The hypothetical imperative (1) If I want what is good for me then I ought to pursue what realizes my natural ends and avoid what frustrates them is something whose truth Aquinas takes to follow from the metaphysical analysis of goodness sketched above. By itself, it does not give us a categorical imperative because the consequent will have force only for someone who accepts the antecedent. But that (2) I do want what is good for me is true of all of us by virtue of our nature as human beings, and is in Aquinas’s view self-evident in any case, being just a variation on his fundamental principle of natural law. These premises yield the conclusion (3) I ought to pursue what realizes my natural ends and avoid what frustrates them. It does have categorical force because (2) has categorical force, and (2) has categorical force because it cannot be otherwise given our nature. Not only the content of our moral obligations but their obligatory character are thus determined, on Aquinas’s analysis, by the metaphysics of final causality or natural teleology. As the neo-Scholastic natural law theorist Michael Cronin has summed up the Thomistic view, “In the fullest sense of the word, then, moral duty is natural. For not only are certain objects natural means to man’s final end, but our desire of that end is natural also, and therefore, the necessity [or obligatory force] of the means is natural” (Science of Ethics, Volume 1, p. 222). Clearly, the “naturalness” of natural law can, as I have emphasized, only be understood in terms of the Aristotelian metaphysics to which Aquinas is committed. But it is also illuminating to compare the natural law to the three other kinds of law distinguished by Aquinas. Most fundamental is what he calls the “eternal law,” which is essentially the order of archetypes or ideas in the divine mind according to which God creates and providentially governs the world (ST I-II.91.1). Once the world, including human beings, is created in accordance with this law, the result is a natural order that human beings as rational animals can come to know and freely choose to act in line with, and “this participation of the eternal law in the rational creature is called the natural law” (ST I-II.91.2). The “natural law,” then, can also be understood in terms of its contrast with eternal law, as the manifestation of the latter within the natural order. Now the natural law provides us with general principles by which individuals and societies ought to be governed, but there are many contingent and concrete details of human life that the natural law does not directly address. To take a standard example, the institution of private property is something we seem suited to given our nature, but there are many forms that institution might take consistent with natural law (cf. ST II-II.66.2). This brings us to “human law,” which is the set of conventional or man-made principles that govern actual human societies, and which gives a “more particular determination” to the general requirements of the natural law as it is applied to concrete cultural and historical circumstances (ST I-II.91.3). Human law, then, is unlike both eternal law and natural law in that it is “devised by human reason” and contingent rather than necessary and unchanging. Finally there is “divine law,” which is law given directly by God, such as the Ten Commandments (ST I-II.91.4–5). This differs from the natural law in being knowable, not through an investigation of the natural order, but only via a divine revelation. It is like human law in being sometimes suited to contingent historical circumstances and thus temporary (as, in Aquinas’s view, the Old Law given through Moses was superseded by the New Law given through Christ) but unlike human law in being infallible and absolutely binding. 

Religion and morality 

This naturally brings us to the question of the extent to which morality depends, in Aquinas’s view, on religion in general and on an appeal to God’s will in particular. Some of what has been said thus far might seem to imply that there is no such dependence, insofar as the content and binding force of the natural law have been said to derive from human nature rather than arbitrary divine commands. On the other hand, the idea that natural law derives from eternal law might seem to indicate that morality ultimately depends on God after all, as does the notion that only God (rather than wealth, pleasure, power, etc.) could be the ultimate good for us. So what is Aquinas’s position? Fulvio Di Blasi has usefully distinguished three approaches commentators have taken to the question of whether natural law, as understood in Thomistic terms, requires something like an Aristotelian metaphysical conception of the natural order and/or an appeal to theological premises concerning the existence and will of God. The first approach, associated with Grisez and Finnis, holds that natural law requires neither the metaphysics nor the theology. A second approach, represented by writers like Henry Veatch and Anthony Lisska, holds that the metaphysics is necessary but not the theology. The third approach holds that both elements are necessary, and is defended by commentators like Ralph McInerny and Di Blasi himself. As has been suggested already, the Grisez– Finnis approach to natural law seems clearly mistaken, at least if intended as an interpretation of Aquinas’s own position. (Its value as a completely independent moral theory is something we cannot address here.) What of the other two approaches? It seems to me there is truth in both of them. From an Aristotelian point of view, the essences and final causes of things are knowable simply by studying the things themselves, without any appeal to the existence or intentions of a creator. (Indeed, though Aristotle himself thought that the existence of a divine unmoved mover could be proved, he did not, as Aquinas later would in his Fifth Way, try to argue that the final causes of things, specifically, required an explanation in theological terms. Aristotle’s own arguments for God were variants of what Aquinas called the First Way.) But at least the core of the theory of natural law follows directly from these metaphysical notions. Hence it seems clear that at least a substantial part of morality can, on a Thomistic account, be known in principle without appealing to God. If we know that the will is naturally ordered to pursuing what the intellect perceives as good, and know that what is in fact good is what realizes our natural ends, then we can know that if we are rational we ought to pursue those ends. Moreover, since those ends can themselves be known through reason, we can arrive at some knowledge of what it is specifically that the natural law requires of us even if we have no knowledge of God. To be sure, if Aquinas is right that God alone can be our ultimate end, then without knowledge of this fact, our understanding of morality will be deficient, to say the least. Still, we would nevertheless have some substantial understanding of it. And while if there is a God he will, of course, be the ultimate explanation of the natural law (since he will be the ultimate explanation of everything), lack of knowledge of God wouldn’t prevent us from knowing something about the natural law, any more than it would prevent us from discovering various scientific truths. So there is some truth to the view defended by Veatch and Lisska. On the other hand, it seems highly implausible to suggest that the existence of God, as Aquinas understands him, could possibly be irrelevant to a Thomistic understanding of natural law. For if God exists, then he cannot fail to be our ultimate end, in which case everything else in our moral lives would necessarily have to be subordinated to our religious obligations; and even the most conservative form of secular life cannot fail to be altered radically when redirected towards a religious end. Hence if God exists an adequate account of the content of morality will necessarily have to reflect this fact. Our understanding of the grounds of moral obligation is also bound to be affected by theological considerations. Indeed, Aquinas takes the view that in the strict sense, “law … is nothing else than an ordinance of reason for the common good, made by him who has care of the community, and promulgated” (ST III.90.4). Like every other form of law, then, the natural law, if it is truly to count as law (rather than a mere counsel of prudence) must be backed by a lawgiver. Since it is a law governing the natural order, the lawgiver in question would just be the source of the natural order, namely God, who promulgates the natural law “by the very fact that God instilled it into man’s mind so as to be known by him naturally” (ST III.90.4). Aquinas’s view seems to be that since things are fully intelligible only when traced back to the creative will of God – who, as pure act, cause of all things, the one absolutely necessary being, perfect goodness, and the supreme intellect, can alone serve as an ultimate explanation of anything – the necessity or obligatory nature of our moral obligations too can also only be fully intelligible when traced back to him. For a rational agent will act only in accordance with what reason and nature command, and precisely because reason and nature command it. But reason and nature only command what they do because God has ordered them that way. Hence a rational agent cognizant of the ultimate source of things will act only in accordance with what the divine will commands, and precisely because the divine will commands it: In this way God Himself is the measure of all beings … Hence His intellect is the measure of all knowledge; His goodness, of all goodness; and, to speak more to the point, His good will, of every good will. Every good will is therefore good by reason of its being conformed to the divine good will. Accordingly, since everyone is obliged to have a good will, he is likewise obliged to have a will conformed to the divine will. (QDV 23.7) Thus there is, from the Thomistic point of view, some truth after all in the “divine command” theory of ethics, even if it is far from the whole story and even though the commands in question are emphatically not arbitrary ones. More to the present point, there is much truth in Di Blasi’s view that Aquinas’s theory of natural law is ultimately as theological as it is metaphysical. But the “ultimately” is important. As Michael Cronin notes, and as we have seen when discussing the Five Ways, the eternal law of God does not move the world directly and immediately, but mediately, i.e., through the operation of secondary causes or causes residing in nature itself; and therefore it is not to be expected that in the moral world the eternal law will be operative without some such intermediate natural principle. (Science of Ethics, vol. 1, p. 213) Hence while what Cronin calls the “ultimate ground” of moral obligation is “eternal law of the Supreme Lawgiver,” there is also “a proximate ground of duty residing in nature itself,” namely the fact that the will is unalterably fixed by nature on the pursuit of the good as its natural end or final cause. And this proximate ground can be studied independently of the ultimate ground, just as the secondary causes of things can be studied without reference to the First Cause. While the Grisez–Finnis reading of Aquinas seems simply mistaken, then, the Veatch–Lisska reading is not mistaken so much as incomplete. A natural law theory with Aristotelian metaphysics but without God is not false, even if it isn’t the whole truth either. It is, we might say, a study of the “proximate grounds” of morality, just as natural science is the study of the proximate or secondary causes of observed phenomena. Still, in morality as in science, a complete account must necessarily be a theological one. In both its metaphysical and its theological commitments, Aquinas’s system of ethics is, like the rest of his philosophy, obviously radically at odds with the assumptions typically made by contemporary moral philosophers. But the main difference may lie in something other than a disagreement over this or that particular ontological thesis or argument for God’s existence, in basic ethos rather than intellectual orientation. The spirit of modern moral philosophy is perhaps summed up best in Kant’s famous characterization of human beings as “ends in themselves” and “selflegislators.” This sort of talk would sound blasphemous and even mad to Aquinas, for whom God alone, as the “first cause and last end of all things,” could possibly be said to be the source of moral law and an end in himself (ST I-II.62.1, as translated by Pegis in Basic Writings of Saint Thomas Aquinas). For Aquinas, we are not here for ourselves, but for the glory of God, and precisely because this is the end set for us by nature, it is in him alone that we can find our true happiness. And it must be emphasized that, as with the other themes we’ve explored in this book, he takes this conclusion to be a matter, not of faith, but of reason itself. Therein lies the sting of Aquinas’s challenge to modernity.