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Aquinas on Natural Law, Natural Inclinations, and Absolute Moral Norms

Published online by Cambridge University Press:  11 September 2025

Matthew Levering
Matthew Levering*
Affiliation:
Department of Theology, University of Saint Mary of the Lake, Mundelein, Illinois, USA
*
Email: mjlevering@yahoo.com
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Abstract

This essay seeks to explain Aquinas’s account of natural law, natural inclinations, and absolute moral norms. According to Aquinas, everything bears the impress of divine wisdom (the divine Word); the cosmos is intelligible and has a teleological order. Aquinas describes this order as expressive of God’s “eternal law,” by which creatures are moved to their perfective ends. Human natural inclinations pertain to how God moves us by our rational nature, as we incline rationally toward the goods that perfect our powers. Since the rational soul is the “form” of the body, everything about the body pertains to the flourishing of the rational creature in interpersonal wisdom and love, rather than being merely a biological substratum. We come to know the human good in the process of seeking particular goods perfective of our modes of existence or powers. The above points ground Aquinas’s account of synderesis, the core precepts of the natural law, and absolute moral norms. These norms, whose intelligibility is darkened by the effects of sin, are reflected in the Decalogue, the teaching of Jesus and Paul, and the Catholic Church’s teaching.

Keywords

Natural lawnatural inclinationsCreatorpreceptsflourishing

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New Blackfriars , Volume 106 , Issue 6 , November 2025 , pp. 527 - 540
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© The Author(s), 2025. Published by Cambridge University Press on behalf of Provincial Council of the English Province of the Order of Preachers.

1. Introduction

The notions of natural law, natural inclinations, and absolute moral norms often meet with suspicion today. Servais Pinckaers observes that, in part, this suspicion arises because of ‘our habit of considering nature and freedom as contraries’.Footnote 1 Moreover, even those willing to entertain natural law doctrine disagree among themselves about what constitutes its basis and content. There are also disagreements about which human inclinations should be prioritized and about the source and status of such inclinations. In addition, moral understanding changes and develops in the world and in the Church, and some scholars think that this undermines both the notion of a stable natural law and the reality of absolute moral norms that hold in any possible context or circumstance.Footnote 2 The notion of human nature is also widely contested, making difficult any appeal to what is ‘natural’ for human beings.Footnote 3

In what follows, therefore, I will seek to illuminate and defend Aquinas’s account of natural law, natural inclinations, and absolute moral precepts. I grant that Aquinas’s perspective requires ideas that are best known to persons who believe in a Creator God and who accept the biblical portrait of reality.Footnote 4 Yet, even if natural law doctrine is articulated by Aquinas partly on the basis of biblical commitments, this does not mean that natural law precepts can be known only by Christians. As we will see, Aquinas’s account of natural law is not fideistic.Footnote 5 Moreover, it is worth keeping in mind that, as Owen Anderson points out, ‘all who reject natural law replace it with a framework that contains the conceptual relationship between law, view of the good, view of human nature, and beliefs about what is real’.Footnote 6 What is in fact real, Aquinas suggests, is the constitution of the cosmos and human nature by divine wisdom and goodness, moving even us sinners toward the wisdom and goodness for which God created us.

2. Aquinas on divine wisdom, goodness, and government

Let me begin by offering a Thomistic account of divine creative wisdom and goodness. According to one of Aquinas’s favorite biblical passages, Wisdom of Solomon 7, wisdom ‘pervades and penetrates all things’ (Wisd 7:24). There is nothing in creation that does not bear the impress of divine wisdom. Wisdom is ‘a reflection of eternal light, a spotless mirror of the working of God, and an image of his goodness’ (Wisd 7:26).Footnote 7 Natural scientists can affirm the intelligibility of the cosmos and the flourishing that is served by core creaturely inclinations.Footnote 8 Christian philosophers can say more. Wojciech Golubiewski remarks, ‘Aquinas presents the principles of operations of natures as constituted by the divine mind and as effects of the divine wisdom and goodness’.Footnote 9 This point merits elaboration here.

In Summa theologiae I-II, q. 91, a. 1, Aquinas teaches that ‘the whole community of the universe is governed by divine reason’, so that ‘the very idea of the government of things in God the ruler of the universe, has the nature of a law’.Footnote 10 The ‘law’ here is God’s eternal idea or his plan for his government of all things to the end for which he created, namely, his own goodness. Divine government involves the effective power of the divine will moving all things to their end (through secondary causes), whereas divine providence is the God’s wise plan for all things.Footnote 11 Aquinas states that ‘all things subject to divine providence are ruled and measured by the eternal law’.Footnote 12 This includes non-rational creatures, since God’s providence encompasses everything. Even though non-rational things cannot share in law strictly speaking – because to possess law interiorly requires having rationality – it remains the case that irrational creatures ‘partake in their own way of the eternal reason’.Footnote 13 The whole of creation, in its dynamic order and agency, shines forth with law or wisdom.

The notion of ‘eternal law’ encompassing the entire universe is a Stoic one, although Aquinas (like his fellow scholastics) draws it from Augustine and develops it further.Footnote 14 Aquinas explains Augustine’s theology of eternal law: ‘Just as in every artificer there pre-exists a type of things that are made by his art, so too in every governor, there must pre-exist the type of the order of those things that are to be done by those who are subject to his government’.Footnote 15 This ‘type’ or eternal divine idea suffuses the whole of creation, across space and time, with reason’s light. Discussing the eternal law, Aquinas comments that ‘law is said to direct human acts by ordaining them to the common good’, and therefore ‘the type of the divine wisdom [i.e. eternal law], as moving all things to their due end, bears the character of law’.Footnote 16 God moves all things toward the ultimate end in diverse ways. Human natural inclinations pertain to how God moves us by our rational nature, as we incline toward the human good. Sin frustrates God’s wise plan as an act against what is truly good for us, but sin cannot frustrate God’s ultimate attainment of the common good of the whole creation.

The wisdom that imbues creation is such that all creatures have inclinations toward their proper ends. Aquinas observes that ‘all things partake somewhat of the eternal law, in so far as, namely, from its being imprinted on them, they derive their respective inclinations to their proper acts and ends’.Footnote 17 Golubiewski explains this point in more technical language, highlighting natural law’s status as a participation in the eternal law. He states, ‘The light of divine intellect as eternal law inscribes practical principles in the human intellect that imitates the eternal ratio determining all creatures’ natural inclinations to their respective actions and ends, according to their natures as modes of participation in the eternal law’.Footnote 18 Put otherwise, reason or wisdom orders the whole of creation. In this context, Aquinas comments that ‘the proper effect of law is to lead its subjects to their proper virtue: and since virtue is that which makes its subject good, it follows that the proper effect of law is to make those to whom it is given, good, either simply or in some particular respect’.Footnote 19

In accord with wisdom’s suffusing the entire creation, Aquinas associates the eternal law with the divine Word. As Aquinas says (in agreement with Augustine), ‘all things that are in the Father’s knowledge, whether they refer to the essence or to the Persons, or to the works of God, are expressed by this Word’.Footnote 20 In the Word, God speaks all that he is and all that he knows. This shows how deeply wisdom characterizes creation. Aquinas makes clear that God’s knowledge is practical, joined to the divine operation of creating. He ties the Word tightly to creation by suggesting that the Word is not only expressive of the idea of all creatures but also causes creatures to be what they are.Footnote 21

All creation, moreover, is governed by God in accordance with the divine wisdom. Let me say a bit more about the divine government. According to Aquinas (here agreeing with Pseudo-Dionysius), ‘the end [or goal] of the government of the world is the essential good, to the participation and similarity of which all things tend’.Footnote 22 The effect of the divine government is ultimately one: ‘assimilation to the supreme good’.Footnote 23 What this means is twofold. First, God’s government aims from eternity to make the rational creature to be utterly good and therefore to become fully like God who is good. Second, the rational creature becomes like God especially by ‘moving others to be good’, just as God does.Footnote 24 This helps to explain why God allows rational creatures to have freedom, despite freedom’s capacity to be abused. Humans are perfected not simply by being good themselves but also by helping others to become good – by acts of mercy and love, going out beyond the self toward the needy other. Aquinas remarks that ‘it is a greater perfection for a thing to be good in itself and also the cause of goodness in others, than only to be good in itself’.Footnote 25 The consummated kingdom of God will be filled, by God’s grace, with saints and angels who by their prayers and works of mercy have assisted others in becoming fully good, living out the New Law that fulfills the precepts of the natural law.

If creation is suffused with reason and inclined toward good, however, what about the terrible things that sinners have done and are doing? Aquinas points out in response that to understand why God permits sin, one would need to apprehend not only the end, but also the whole order of causes by which the end is achieved, including defective (sinful) causes. But we do not yet even know the end in its fullness, although we know that the end is the kingdom of God. As Aquinas says, when ‘from one point of view something seems to evade the order of divine providence considered in regard to one particular cause, it must necessarily come back to that order as regards some other cause’.Footnote 26 When a contingent cause fails, the complex order of the divine government to the ultimate end does not thereby collapse.

3. Rational natural inclinations to the human (body–soul) good

According to Aquinas, ‘All natural things were produced by the divine art, and so may be called God’s works of art’.Footnote 27 This applies preeminently to the body–soul composite that is the human person. It would be a mistake simply to think of the soul and body as two distinct parts, since in fact the rational soul is the ‘form’ of the body, with the result that everything about the body pertains to the flourishing of the rational creature (the human person). As Aquinas puts it, ‘The proximate end of the human body is the rational soul and its operations’.Footnote 28 For example, human beings stand erect and face outward, rather than facing the ground; and human hands, mouth, and tongue are ordered to communication and speech. The human body is formed in every way to express and serve the rational soul in its ordering toward interpersonal wisdom and love.

As noted above, at the root of natural law is the fact that we human beings, in our body–soul unity, rationally desire or incline toward the human good – and thus implicitly toward God, infinite goodness, who constitutes our perfect beatitude.Footnote 29 Thus, for Aquinas (in the words of Pinckaers), ‘inclinations, like the natural law, [are] God’s most precious work in the human person, a direct unique participation in his own wisdom, goodness, and freedom’.Footnote 30 The good that humans rationally desire as fully perfective of their being is ultimately a universal good, a happiness or fulfillment of human powers that can only be had in God, both because of God’s infinite goodness and because of God’s ability to sustain human existence beyond the grave.Footnote 31

With respect to how humans know what constitutes the good for us, Aquinas suggests that we come to know it in the process of seeking that which perfects our existence – that is, we know it in seeking particular goods befitting our body–soul nature.Footnote 32 Edward Feser explains in Aristotelian terms that we incline naturally toward ‘the final causes or natural teleology of our various capacities’.Footnote 33 Yet, while we consciously desire goods perfective of our modes of existence, natural law does not require an explicit knowledge that happiness (the perfection of our existence) exists. It is enough to incline naturally toward it, as in fact we do. As Stephen Brock says, practical reason operates ‘with the whole human good [happiness, integral human perfection] somehow in view and sees everything else in relation to it’, but ‘what we naturally or immediately know about the good as a whole is very sketchy’.Footnote 34 Nevertheless, there are certain goods that we can immediately recognize as suitable for human nature. These goods specify the natural inclinations.Footnote 35

Aquinas never tires of emphasizing that human nature and natural inclinations aim toward the good and therefore are reasonable. Even sinners (whose minds have been distorted by pride, or whose passions have been distorted by concupiscence) aim toward a good; the problem is that sinners ‘resist some particular good, which belongs to their nature or state’ and so do evil and may miss out on happiness.Footnote 36 Sinners do not lack natural inclinations toward the ends that perfect human nature. Nor do sinners lack the primary precepts of natural law. Brock speaks of the ‘practical reason’s common principles, which are the primary precepts of natural law and which require no instruction’.Footnote 37 Aquinas thinks that these primary precepts are held in the human mind through the habit of synderesis.Footnote 38 In an important sense, everyone knows natural law, namely, at the level of its primary principles or precepts.

Nevertheless, fallen human beings generally incline toward vice. How then do our natural inclinations differ from inclinations toward vice? The answer is that vice consists in seeking a particular good in a way that impedes the attainment of the human end. Brock underscores that for Aquinas, the good that natural law commands us to pursue is a good because it is an end for us.Footnote 39 An end is something that we apprehend as serving the perfecting of our body–soul nature. We naturally (rationally) incline toward such goods as ends, apprehending them as perfective of human existence, individually and socially.Footnote 40

Brock maintains that natural inclinations are, therefore, not pre-rational but rational, rooted in our rational apprehension of something as a good and as an end for us. As he puts it, ‘What reason naturally apprehends as good, the rational appetite – the will – naturally desires…. Man, as man, is naturally inclined to certain things, because reason naturally apprehends them as good’.Footnote 41 Elsewhere, summing up his view of Aquinas’s position, Brock states: ‘[T]he inclinations are to be seen as rooted in the understanding of the goodness of the things that are their objects. That understanding would not itself depend on the inclinations’.Footnote 42 The natural inclinations accord with our apprehension of the goods toward which the inclinations are oriented: we incline toward these goods precisely as befitting our body–soul nature. Since there is a certain order among these goods – some are more fundamental than others – ‘the order of the precepts of natural law is according to the order of man’s natural inclinations’.Footnote 43

4. Natural law and moral absolutes

According to Aquinas, natural law contains some precepts that are moral absolutes, meaning that they bind in every possible circumstance. What are these precepts?

In Summa theologiae II-II, q. 122, a. 1, obj. 1, Aquinas remarks, ‘The precepts of the decalogue are the first principles of the Law: and the natural reason assents to them at once, as to principles that are most evident’.Footnote 44 The precepts of the Decalogue include such things as the necessity of worshipping God, the wrongness of adultery, the mandate to honor one’s parents, and the condemnation of killing the innocent. Here Aquinas indicates that these precepts are self-evident to practical reason. Regarding this text, Lawrence Dewan comments,

St. Thomas changed his view of the presence of the per se notum as regards the precepts of natural law. Thus, while in the Prima Secundae the Ten Commandments are presented as immediate conclusions from the first principles, by the time he writes the Secunda Secundae Thomas has decided that they are most manifest principles of natural law.Footnote 45

The per se nota principles (or precepts) of the natural law are known by us as part of our being rational, rather than requiring to be deduced as conclusions by means of a process of reasoning.

Earlier, in Summa theologiae I-II, q. 100, a. 3, Aquinas states that ‘the decalogue includes those precepts the knowledge of which man has immediately from God. Such are those which with but slight reflection can be gathered at once from the first general principles: and those also which become known to man immediately through divinely infused faith’.Footnote 46 Here Aquinas proposes that the precepts of the Decalogue mentioned above are not self-evident but rather require a least a small amount of reasoning to obtain. In this text, Aquinas holds that the self-evident first principles are ‘that one should do evil to no man, and other similar principles’.Footnote 47

According to Aquinas, the heart of the divine wisdom contained in Israel’s Law is the Decalogue given by God directly to Moses on Mount Sinai (Exod 20; 31:18; 34:29; Deut 5).Footnote 48 In the New Testament, the Mosaic Law is described as having been given through the mediation of angels (Heb 2:2; Acts 7:53), without undermining the Decalogue’s divine origin. Aquinas affirms the centrality of the Decalogue, its status as the core of natural law, and its derivation from God. Although the Decalogue is privileged, all the moral precepts of the Mosaic Law belong to the natural law, even if many of the moral precepts can only be arrived at via a difficult process of reasoning.

In I-II, q. 100, a. 1, Aquinas brings together what we find in II-II, q. 122, a. 1, obj. 1 and I-II, q. 100, a. 3. He states that ‘there are certain things which the natural reason of every man, of its own accord and at once, judges to be done or not to be done: e.g., Honor thy father and thy mother, and, Thou shalt not kill, Thou shalt not steal; and these belong to the law of nature absolutely’.Footnote 49 On this view, there are no circumstances in which dishonoring one’s father and mother can be morally good, although not all possible ways of honoring one’s parents are requisite. There are also no circumstances in which directly choosing to kill an innocent person can be good.

In the Gospels, as Aquinas recognizes, Jesus identifies some precepts of the Decalogue as requiring absolute adherence in all circumstances.Footnote 50 For instance, when a rich young man approaches him and asks him how to inherit eternal life, Jesus first answers, ‘If you would enter life, keep the commandments’ (Mt 19:17). When the rich young man asks which commandments Jesus has in mind, Jesus specifies, ‘You shall not kill, You shall not commit adultery, you shall not steal, You shall not bear false witness, Honor your father and mother, and, You shall love your neighbor as yourself’ (Mt 19:18–19). In his Sermon on the Mount, Jesus intensifies these commandments, warning, for example, against lust as an interior desire for adultery and against anger as an interior desire for killing (Mt 5:21–32). He likewise teaches that marriage is indissoluble, and therefore remarriage while one’s divorced spouse is alive entails adultery.Footnote 51

Paul takes up this sense of absolute moral precepts, whose violation separates a person from God’s kingdom unless the person repents and is reunited to Christ. Paul also affirms the existence of natural law, referring to the Gentiles who ‘do by nature what the law requires’ (Rom 2:14).Footnote 52 At the same time, Paul condemns the Gentiles for their idolatrous worship of creatures and their same-sex sexual practices (Rom 1:18–27).Footnote 53 Paul lists various sinful acts and underlying dispositions: ‘They [idolaters] were filled with all manner of wickedness, evil, covetousness, malice. Full of envy, murder, strife, deceit, malignity, they are gossips, slanderers, haters of God, insolent, haughty, boastful, inventors of evil, disobedient to parents, foolish, faithless, heartless, ruthless’ (Rom 2:29–31). Paul teaches that people who act in these ways in fact ‘know God’s decree that those who do such things deserve to die’ (Rom 1:32). They know this ‘decree’ not through the Mosaic Law but through the law of nature. Paul’s point is not to suggest that there are people who, having behaved well, have no need for salvation through faith in Jesus Christ. Rather, Paul holds that everyone has sinned; everyone needs the mercy of God.

In preaching the merciful reconciliation won by Jesus Christ, Paul does not place absolute moral norms to the side as though Christ’s mercy has made them irrelevant.Footnote 54 On the contrary, he insists that cleaving to Christ requires moral conversion for all of us. He instructs the Corinthians, ‘Do not be deceived; neither the immoral, nor idolaters, nor adulterers, nor homosexuals, nor thieves, nor the greedy, nor drunkards, nor revilers, nor robbers will inherit the kingdom of God’ (1 Cor 6:9–10). Christians have been all these things, but cleaving to Christ has converted them. Paul states, ‘And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and in the Spirit of our God’ (1 Cor 6:11).

Paul is also aware that the existence of absolute moral norms can be obscured by passions or by societal customs. He describes the Gentiles as having become ‘futile in their thinking’, so that ‘their senseless minds were darkened’ (Rom 1:21). As noted above, they still knew ‘God’s decree’ (Rom 1:32) about the moral life, but they allowed the force of this decree to be obscured. Aquinas states that with respect to the primary precepts,

the natural law, in the abstract, can nowise be blotted out from men’s hearts. But it is blotted out in the case of a particular action, in so far as reason is hindered from applying the general principle to a particular point of practice, on account of concupiscence or some other passion.Footnote 55

Thus, many people who would be horrified at the killing even of a healthy dog have come to accept that, in certain circumstances, the abortion of a human being in his or her mother’s womb is morally licit.Footnote 56 For his part, Aquinas mentions cultures in which (so he thinks) theft was deemed licit and in which certain kinds of homosexual acts were deemed licit.Footnote 57

Brock points out that for Aquinas even ‘the prohibition of fornication … and even the prohibition of the so-called sins against nature [e.g. homosexual acts] pertain to the instruction of the wise’.Footnote 58 This point explains why God chose to reveal the Decalogue, notwithstanding the self-evident (or nearly self-evident) character of the Decalogue’s absolute moral norms. As Brock says, ‘under the conditions of sin, even many of the precepts that belong to natural law absolutely, and indeed the most important of them, seem to need divine help, not only for actual compliance with them – that certainly requires grace – but also for a more than tenuous, merely notional or theoretical hold on them’.Footnote 59

In a fallen world, natural law is insufficient for ensuring that absolute moral norms will be clearly perceived, let alone obeyed. Yet, although our sins wound us deeply, they cannot erase natural law from our mind, and they cannot erase our fundamental ‘inclination to goodness and truth’.Footnote 60

5. Conclusion

I began this essay by observing that, for Aquinas, the cosmos is suffused by divine wisdom; it is intelligible and ordered toward ends. In his wisdom (and thus his Word), God has created everything to share in his goodness. To say that creatures are suffused by God’s creative wisdom, then, is to say that creatures are made for goodness as their ultimate end. Nature is imprinted by reason and ordered dynamically toward good. The goods that perfect created things are the ends of creatures; and divine wisdom ensures that creatures naturally incline toward their ends. Nature involves the convergence of wisdom, goodness, and inclination.

This broad account of nature – and of the ‘law’ that suffuses creation – forms the foundation for natural law and the framework in which absolute moral precepts make sense. There are some actions that, in whatever circumstances and with whatever intention, violate the ends of human nature and cut against our rational natural inclinations. In this regard, I focused on the biblical understanding of absolute (universally binding and non-dispensable) moral precepts, in light of Aquinas’s teaching about the same. Moral absolutes such as those against adultery and against the killing of the innocent serve to promote, in the words of John Finnis, ‘the wisdom of action which expresses a heart really in line with, toward, the ultimate human end and good’.Footnote 61

In light of the divine wisdom – the wisdom revealed preeminently in the incarnate Word – we can trust the goodness of our created ends and of our rational inclinations toward those ends. As we have seen, these inclinations are toward identifiable ends that perfect the powers of our soul-body human nature, which is a social or political nature whose ultimate end is God.Footnote 62 The natural inclinations are not merely any inclination. This fact becomes fully intelligible in a virtuous life, lived in accordance with our rational participation in God’s eternal law for human flourishing. We can choose to seek goods in a manner that violates this wise ordering, but such actions ultimately produce frustration, not individual and social flourishing.

The account offered by my essay may be summed up by consideration of Psalm 19.Footnote 63 The Psalmist rejoices in the divine wisdom that can be perceived in the orderliness of the stars and the sun. The non-rational natural inclinations of the heavenly bodies exhibit the effective power of the wise and good Creator. Within this context of the cosmos as an ordered and intelligible material whole, the Psalmist turns to the Law that Israel has received from God, including the Decalogue. In obeying the precepts of the Torah, says the Psalmist, ‘there is great reward’ (Ps 19:11). These precepts lead to flourishing, just as the heavenly bodies, when moving in accordance with their natural ‘circuit’ (Ps 19:6), comprise a beautiful order that (in the case of the sun) is life-giving to us. The Psalmist proclaims, ‘The law of the Lord is perfect, reviving the soul; the testimony of the Lord is sure, making wise the simple’ (Ps 19:7). At the same time, the Psalmist knows that his mind remains clouded by sin, and he prays, ‘But who can discern his errors? Clear me from hidden faults’ (Ps 19:12).

Indeed, we need instruction and grace to apprehend the natural law fully and to live by it well. In the communion of the Church, we find this instruction and grace, if only we will receive it. Natural law reasoning needs Christ’s Spirit-filled, cruciform Body.

References

1 Servais Pinckaers OP, The Sources of Christian Ethics, trans. Mary Thomas Noble OP (Washington, D.C.: Catholic University of America Press, 1995), 400. Pinckaers goes on to say, ‘In the physical or animal world, nature, whatever its variations, determines the movements it produces in their entirety. Spiritual nature, on the other hand, is such that the inclinations proceeding from it, far from opposing its freedom by setting limits on it, cause and increase its freedom as a source, providing it with principles of truth and goodness…. [W]e are free not in spite of our natural inclinations but because of them’ (401–2).

2 In Moral Absolutes: Tradition, Revision, and Truth (Washington, D.C.: Catholic University of America Press, 1991), John Finnis offers a helpful account (and defense) of the Church’s changes. For approaches to these issues from the perspective of revisionist Catholic ethics, see John T. Noonan, Jr., A Church That Can and Cannot Change: The Development of Catholic Moral Teaching (Notre Dame: University of Notre Dame Press, 2005); and Richard M. Gula, S.S., What Are They Saying about Moral Norms? (New York: Paulist, 1982).

3 For Karl Rahner SJ’s view that ‘human nature’ is ever-changing (ultimately because, for Rahner, ‘human nature’ means simply the expression of ever-evolving human spirit), see for instance his 1970 essay ‘Basic Observations on the Subject of Changeable and Unchangeable Factors in the Church,’ in his Theological Investigations, vol. 14: Ecclesiology, Questions in the Church, the Church in the World, trans. David Bourke (New York: Crossroad, 1976), 15; and see also Rahner, The Shape of the Church to Come, trans. Edward Quinn (New York: Seabury, 1974). For positivist perspectives that deny the existence of human nature, see Owen Anderson, in The Natural Moral Law: The Good After Modernity (Cambridge: Cambridge University Press, 2012), 39.

4 For further discussion of this and other matters, see my Biblical Natural Law: A Theocentric and Teleological Approach (Oxford: Oxford University Press, 2008)

5 On this point, see Jean-Rémi Lanavère, ‘Pour quelles raisons la loi naturelle est-elle naturelle? La naturalité de la loi naturelle chez Thomas d’Aquin’, Revue Thomiste 122 (2022): 71–88; F. Russell Hittinger, ‘Yves R. Simon on Natural Law and Practical Reason’, in Hittinger, On the Dignity of Society: Catholic Social Teaching and Natural Law, ed. Scott J. Roniger (Washington, D.C.: Catholic University of America Press, 2024), 201–24. Lanavère directs attention to Summa theologiae I-II, q. 10, a. 1, where Aquinas explains that a thing ‘is said to be natural to a thing which befits it in respect of its substance…. Wherefore, taking nature in this sense, it is necessary that the principle of whatever belongs to a thing, be a natural principle’ (trans. Fathers of the English Dominican Province; Westminster, MD: Christian Classics, 1981). As Lanavère comments, ‘The difference between acting per naturam and acting per rationem et voluntatem… is surmounted in the case of humans, who act, as regards the principles of their action, per naturem, and, as regards the realization of these actions, per rationem et voluntatem’ (‘Pour quelles raisons la loi naturelle est-elle naturelle?,’ 77).

6 Anderson, The Natural Moral Law, 31.

7 See the discussion of these verses in Mark Giszczak, Wisdom of Solomon (Grand Rapids, MI: Baker Academic, 2024), 89–90. See also John 1 and further passages in the Wisdom literature, including Proverbs 8 and Sirach 24. For commentary, see Ben Witherington, III, Jesus the Sage: The Pilgrimage of Wisdom (Minneapolis, MN: Fortress, 1994); Witherington, John’s Wisdom: A Commentary on the Fourth Gospel (Louisville, KY: Westminster John Knox, 1995); and Leo G. Perdue, Wisdom and Creation: The Theology of Wisdom Literature (Nashville, TN: Abingdon, 1994).

8 See Neil deGrasse Tyson and Donald Goldsmith, Origins: Fourteen Billion Years of Cosmic Evolution (New York: W. W. Norton, 2004); J. Scott Turner, The Tinkerer’s Accomplice: How Design Emerges from Life Itself (Cambridge, MA: Harvard University Press, 2007); Jacob Berkowitz, The Stardust Revolution: The New Story of Our Origin in the Stars (Amherst, NY: Prometheus Books, 2012); and Peter Dear, The Intelligibility of Nature: How Science Makes Sense of the World (Chicago: University of Chicago Press, 2006). Tyson and Goldsmith remark with awe, ‘Like the microscopic strands of DNA that predetermine the identity of a macroscopic species and the unique properties of its members, the modern look and feel of the cosmos was writ in the fabric of its earliest moments and carried relentlessly through time and space’ (Origins, 143).

9 Wojciech Golubiewski, Aquinas on Imitation of Nature: Source of Principles of Moral Action (Washington, D.C.: Catholic University of America Press, 2022), 120.

10 I-II, q. 91, a. 1.

11 See Jean-Pierre Torrell OP, ‘Dieu conduit toutes choses vers leur fin: Providence et gouvernement divin chez Thomas d’Aquin’, in Ende und Vollendung. Eschatologische Perspektiven im Mittelalter, ed. Jan A. Aertsen and Martin Pickavé (Berlin: De Gruyter, 2002), 561–94.

12 I-II, q. 91, a. 2.

13 I-II, q. 91, a. 2, ad 3.

14 For further discussion, see Joseph Collins OP, ‘God’s Eternal Law’, The Thomist 23 (1960): 497–532.

15 I-II, q. 93, a. 1. On the divine ideas more broadly, see Gregory T. Doolan, Aquinas on the Divine Ideas as Exemplar Causes (Washington, D.C.: Catholic University of America Press, 2008); and the first chapter of my Engaging the Doctrine of Creation: Cosmos, Creatures, and the Wise and Good Creator (Grand Rapids, MI: Baker Academic, 2017).

16 I-II, q. 93, a. 1 and ad 1. For elaboration of this point, see Stephen L. Brock, ‘The Primacy of the Common Good and the Foundations of Natural Law in St. Thomas’, in Ressourcement Thomism: Sacred Doctrine, the Sacraments, and the Moral Life, ed. Reinhard Hütter and Matthew Levering (Washington, D.C.: Catholic University of America Press, 2010), 234–55.

17 I-II, q. 91, a. 2.

18 Golubiewski, Aquinas on Imitation of Nature, 145. With respect to this comparison between human natural inclinations and the inclinations of non-rational things, see also Stephen L. Brock, Action and Conduct: Thomas Aquinas and the Theory of Action (Edinburgh: T&T Clark, 1998), 29–42. See also Lanavère, ‘Pour quelles raisons la loi naturelle est-elle naturelle?’, 79, on the lex indita.

19 I-II, q. 92, a. 1. In The Perfection of Desire: Habit, Reason, and Virtue in Aquinas’s Summa Theologiae (Milwaukee, WI: Marquette University Press, 2018), Jean Porter defines virtue as follows: ‘According to Aquinas, a virtue is simply a good habit of a specific faculty, good in the unrestricted sense of being desirable or praiseworthy without qualification (I-II 55.4). As such, it is a perfection, in the sense of being a full and appropriate development of a human faculty. Like all habits, the virtues are defined by the kinds of actions that they characteristically produce, which Aquinas identifies as the object of the virtue (I-II 54.2, 60.1; cf. II-II 23.4). Thus, for example, the object of acquired temperance is consumption in accordance with the needs of the body’ (47–48; cf. 63). If human nature had no law (no wise ordering to the human good), it could have no virtuous embodiment of that wise ordering either. See also Daniel J. Daly, ‘From Nature to Second Nature: The Relationship of the Natural Law and the Acquired Virtues in the Summa Theologiae,’ Angelicum 88 (2011): 693–715; Dominic Farrell LC, The Ends of the Moral Virtues and the First Principles of Practical Reason in Thomas Aquinas (Rome: Gregorian University Press, 2012); Russell Hittinger, ‘After MacIntyre: Natural Law Theory, Virtue Ethics, and Eudaimonia’, International Philosophical Quarterly 29 (1989): 449–61; and Angela M. McKay, ‘Synderesis, Law, and Virtue’, in The Normativity of the Natural: Human Goods, Human Virtues, and Human Flourishing, ed. Mark J. Cherry (Dordrecht: Springer, 2009), 33–44.

20 I-II, q. 93, a. 1, ad 2. For discussion, see Gilles Emery OP, The Trinitarian Theology of Saint Thomas Aquinas, trans. Francesca Aran Murphy (Oxford: Oxford University Press, 2011).

21 I, q. 34, a. 3.

22 I, q. 103, a. 4. For further discussion of the divine government, see François Daguet, Théologie du dessein divin chez Thomas d’Aquin. Finis omnium Ecclesia (Paris: Vrin, 2003).

23 I, q. 103, a. 4.

24 I, q. 103, a. 4.

25 I, q. 103, a. 6.

26 I, q. 103, a. 7.

27 I, q. 91, a. 3.

28 I, q. 91, a. 3. For Aquinas’s hylomorphic account of human nature, see Jason T. Eberl, The Nature of Human Persons: Metaphysics and Bioethics (Notre Dame: University of Notre Dame Press, 2020). See also the intriguing studies by James Dominic Rooney OP, Material Objects in Confucian and Aristotelian Metaphysics: The Inevitability of Hylomorphism (London: Bloomsbury, 2022); and Sebastian Morello, The World Is God’s Icon: Creator and Creation in the Platonic Thought of Thomas Aquinas (Brooklyn, NY: Angelico, 2020).

29 On God and natural law, see Lawrence Dewan OP, ‘St. Thomas, Natural Law, and Universal Ethics’, Nova et Vetera 9 (2011): 737–62, especially 742–55. See also International Theological Commission, ‘In Search of a Universal Ethic’, §§62–63; Fulvio Di Blasi, God and the Natural Law: A Rereading of Thomas Aquinas (South Bend, IN: St. Augustine’s Press, 2002). At the same time, as James Jacobs avers, for Aquinas ‘[r]ecognition of God as the creator of the world, providentially governing it, and making redemption of human beings possible is not a condition for the grasp of natural law’ – though I think it makes affirming the existence of natural law and living out its precepts much easier. See Jacobs, ‘Natural Law in Medieval Jewish Philosophy’, in Traditions of Natural Law in Medieval Philosophy, ed. Dominic Farrell, L.C. (Washington, D.C.: Catholic University of America Press, 2023), 25–48, at 45.

30 Pinckaers, The Sources of Christian Ethics, 403. See also Edward Feser, ‘Being, the Good, and the Guise of the Good’, in his Neo-Scholastic Essays (South Bend, IN: St. Augustine’s Press, 2015), 297–320; as well as his ‘Teleology: A Shopper’s Guide’, Philosophia Christi 12 (2010): 142–59. Drawing upon Aquinas and Philippa Foot’s Natural Goodness (Oxford: Clarendon, 2001), Feser argues, ‘What is true of animals in general is true of human beings. Like non-rational animals, we have various ends to which we are directed by nature, and these determine what is good for us’ (‘Being, the Good, and the Guise of the Good,’ 301). In this vein, see also Alasdair MacIntyre, Dependent Rational Animals: Why Human Beings Need the Virtues (Chicago: Open Court, 1999).

31 See Brock, ‘Natural Law, the Understanding of Principles, and the Universal Good’, 687–89.

32 See Pinckaers, The Sources of Christian Ethics, 408–12; and see Porter, The Perfection of Desire, 85–86: ‘The good to which Aquinas refers should not be understood in a purely formal way, as if men and women were naturally oriented towards goodness as an abstract category, or some kind of Good in General. Rather, men and women necessarily desire and seek the distinctively human good, that is to say, perfection [i.e., happiness] in accordance with the formal principles of human existence (I-II 1.7). What is more, they do so in a characteristically human way, through rational reflection, deliberation, and choice’.

33 Feser, ‘Being, the Good, and the Guise of the Good’, 301. Feser adds that ‘human beings, like everything else, have various ends the realization 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, practical reason is directed by nature toward the pursuit of what the intellect perceives to be good; what is in fact good is the realization or fulfillment of the various potentials and ends inherent in human nature; and thus a correctly informed and rational person will perceive this and, accordingly, direct his actions towards the realization or fulfillment of those potentials and ends. In this sense, good action is just that which is “in accord with reason”’ (‘Being, the Good, and the Guise of the Good’, 314).

34 Brock, ‘Natural Law, the Understanding of Principles, and the Universal Good’, 693, 703.

35 See Stephen L. Brock, The Light That Binds: A Study in Thomas Aquinas’s Metaphysics of Natural Law (Eugene, OR: Pickwick, 2020), 158–59.

36 I, q. 103, a. 8, ad 1. Porter remarks that for Aquinas, ‘the will is always free to turn towards incomplete or vicious forms of life, because even these represent limited kinds of perfection, ways of developing and expressing one’s human capacities (I-II 78.1, II-II 25.7)’ (The Perfection of Desire, 136). However, vice frustrates the ends that are perfective of human nature and thereby stunts the vicious person. An inclination toward vice is not a natural inclination in Aquinas’s sense.

37 Brock, The Light That Binds, 224.

38 Porter discusses this in the context of synderesis (although she does not mention law): ‘Prudence is a habit of the practical intellect, which informs it in such a way as to facilitate sound, effective reasoning with respect to moral matters (II-II 47.2). The intellect informed by prudence takes its starting points from the first principles of practical reason, which are present to the intellect through the habitual knowledge of the first principles identified by the traditional term, synderesis (II-II 47.6 ad 3; cf. I 79.12). However, this in itself would not serve to distinguish prudence from any other kind of practical disposition, since all practical reasoning necessarily starts from the first principle of practical reasoning. In order to capture what is distinctive about prudence as a virtuous disposition, we need to add that it takes its starting points as these are specified through the formal ideals of the mean of the particular virtues, which set the ends towards which prudence is directed (II-II 47.6; cf. I-II 65.1)’ (The Perfection of Desire, 79).

39 See Brock, The Light That Binds, 126.

40 See also Steven A. Long, The Teleological Grammar of the Moral Act (Naples, FL: Sapientia Press, 2006), 7: ‘Prior to any practical agency of the human subject, one must know the end which one then ensuingly comes to desire’. Long puts these words in italics. As Pinckaers says, ‘The good of a being lies in the perfection proper to its nature. Human good will be a good conformed to the human intellect, as grasped by our distinctive faculty’ (Pinckaers, The Sources of Christian Ethics, 418).

41 Brock, The Light That Binds, 128; see also Brock, ‘Natural Inclination and the Intelligibility of the Good in Thomistic Natural Law’, Vera Lex 6 (2005): 57–78. Pinckaers adopts a somewhat different position, suggesting that the natural inclination to self-preservation, for example, ‘first appears’ in us on ‘the physical plane’ and then is taken up by us on ‘the spiritual level’ (The Sources of Christian Ethics, 424). At the same time, Pinckaers emphasizes that the biological, animal, and rational natural inclinations in us ‘are joined together in a natural unity comparable to the unity of the members of the body…. The rational part encompasses the biological and psychical parts, giving them a new dimension and capacities’ (422). With respect to the natural inclination to self-preservation, Pinckaers holds that it is rationally the source of our care for the lives of others, and therefore it ‘is a certain participation in the love with which God loves himself in his own essence and in his works, causing him to will the conservation and perfection of all beings, loved by him’ (426). See also Steven Jensen’s argument in Knowing the Natural Law: From Precepts and Inclinations to Deriving Oughts (Washington, D.C.: Catholic University of America Press, 2015) that the will is the whole person’s inclination toward the whole good of the person. It follows that the non-rational natural inclinations toward procreation or self-preservation do not stand on their own, morally speaking. By contrast to Brock, Jensen holds that the will takes up non-rational natural inclinations as part of the good of the whole person. Jenson notes that his view does not entail that the will and (for example) the procreative inclination are in a call-and-response relationship, as though the good of the procreative inclination were independent. Jensen explains that the movement toward the human good is the movement of the whole person.

42 Brock, ‘Natural Law, the Understanding of Principles, and Universal Good’, 679; cf. 683–84.

43 Brock, The Light That Binds, 128. It is also the case, as Steven Long says (and as Brock likewise maintains), that ‘the teleological order is made effective… through the development of virtuous dispositions both moral and intellectual’ (Long, The Teleological Grammar of the Moral Act, 88).

44 II-II, q. 122, a. 1, obj. 1.

45 Lawrence Dewan OP, ‘Jean Porter on Natural Law: Thomistic Notes’, The Thomist 66 (2002): 275–309, at 279.

46 For discussion, see Porter, The Perfection of Desire, 107–10. She notes that for Albert the Great, ‘the basic moral precepts of the Decalogue are in some way self-evident’ (107). Porter argues that for Aquinas, ‘The intellect spontaneously grasps the first principle of practical reason as applied to relations to others, and then on that basis it derives the precepts of the Decalogue (I-II 100.3,5)’ (109).

47 I-II, q. 100, a. 3.

48 For further discussion, see Randall L. Smith, ‘What the Old Law reveals about the Natural Law According to Thomas Aquinas’, The Thomist 75 (2011): 95–139.

49 I-II, q. 100, a. 1.

50 For discussion of Jesus’ inclusion of the natural law in his promulgation of the New Law, see Scott J. Roniger, ‘Self-Knowledge, Friendship, and the Promulgation of the Natural Law’, Nova et Vetera 21 (2023): 287–334, at 332.

51 For the connection here with natural law, see Josef Fuchs SJ, Natural Law: A Theological Investigation, trans. Helmut Reckter SJ and John A. Dowling (New York: Sheed and Ward, 1965), 33–37.

52 For further discussion of Romans 2 (including in the exegesis of the Church Fathers, as well as in the work of some contemporary scholars who deny it has natural law in view), see my ‘Christians and Natural Law’, in Anver Emon, Matthew Levering, and David Novak, Natural Law: A Jewish, Christian, and Islamic Trialogue (Oxford: Oxford University Press, 2014), 66–110. See also C. John Collins, ‘Echoes of Aristotle in Romans 2:14–15: Or, Maybe Abimelech Was Not So Bad After All’, Journal of Markets and Morality 13 (2010): 123–73.

53 See my ‘Knowing What Is “Natural”: Thomas Aquinas and Luke Timothy Johnson on Romans 1-2’, Logos 12 (2009): 117–42. On biblical and theological grounds, I address contemporary Catholic theologians who are calling for the sacrament of marriage to include same-sex couples in my Engaging the Doctrine of the Sacraments (Elk Grove Village, IL: Word on Fire Academic, forthcoming); see, for the view that I oppose, Todd A. Salzman and Michael G. Lawler, Pope Francis, Marriage, and Same-Sex Civil Unions (Lanham, MD: Lexington, 2024); and Bridget Burke Ravizza, The Sacrament of Same-Sex Marriage: An Inclusive Vision for the Catholic Church (Lanham, MD: Sheed & Ward, 2024). For Aquinas on homosexual acts and on marriage, see my chapter on chastity in Aquinas’s Eschatological Ethics and the Virtue of Temperance (Notre Dame: University of Notre Dame Press, 2019) and chapter 4 of my The Indissolubility of Marriage: Amoris Laetitia in Context (San Francisco: Ignatius, 2019).

54 For further discussion, see Fuchs, Natural Law, 14–32.

55 I-II, q. 94, a. 6.

56 For an example of Catholic theology in support of abortion in a wide array of circumstances, see Emily Reimer-Barry’s Reproductive Justice and the Catholic Church: Advancing Pragmatic Solidarity with Pregnant Women (Lanham, MD: Sheed & Ward, 2024). Reimer-Barry’s book receives back-cover praise from leading Catholic moral theologians such as Lisa Sowle Cahill, Cristina L. H. Traina, Hille Haker, and Todd Salzman. Reimer-Barry rejects ‘an abortion discourse rooted in moral absolutism’ and advocates for redescribing abortion not as killing as innocent human being but as ‘withdrawal of life support, return of potential life to God, tragic dilemma, and premoral disvalue’ (218). She argues that attention should focus on changing the ‘structural injustices’ that lead women to choose abortion (219), although the issue of sex outside the context of marriage – certainly a central root cause of abortion – does not receive serious attention in her book. She focuses instead on laudable things that, by and large, cannot easily be guaranteed: ‘good jobs and fair wages’ with good benefits and flexible hours; ‘safe housing and equal opportunities for home ownership’; ‘affordable nutrition’; ‘affordable and accessible health care’; ‘affordable childcare’; ‘just adoption and foster care programs’; ‘quality public education’; ‘increased supports for raising children with special needs’; ‘freedom from sexual and relationship violence’ (144). For marriage as an important part of Catholic Social Teaching (and social justice), see the final chapter of my Engaging the Doctrine of Marriage: Human Marriage as the Image and Sacrament of the Marriage of God and Creation (Eugene, OR: Cascade, 2020).

57 I-II, q. 94, a. 4. For discussion, see Kevin L. Flannery SJ, ‘Determinacy in Natural Law’, Nova et Vetera 9 (2011): 763–73, arguing that Aquinas does not mean that the application of the primary precepts of natural law is ‘indeterminate’ in matters of detail. This is a crucial point, since many moral theologians today, including Porter and Traina, suggest that prudential complexity, in light of changing cultural norms and the diverse and contingent circumstances of life, swamps absolute moral norms or at least requires them to be derived consensually and provisionally (and therefore not as absolutes). See Jean Porter, ‘Does the Natural Law Provide a Universally Valid Morality?’ in Intractable Disputes about the Natural Law: Alasdair MacIntyre and His Critics, ed. Lawrence S. Cunningham (Notre Dame: University of Notre Dame Press, 2009), 53–95, at 58, 72, 86; Porter, Nature as Reason, 335–39; Cristina L. H. Traina, Feminist Ethics and Natural Law: The End of Anathemas (Washington, D.C.: Georgetown University Press, 1999). See also Cynthia S. W. Crysdale, ‘Revisioning Natural Law: From the Classicist Paradigm to Emergent Probability’, Theological Studies 56 (1995): 464–84.

58 Brock, The Light That Binds, 223–24. Regarding the identity of ‘the wise’, see two essays by Lawrence J. Welch: ‘Christ, the Moral Law, and the Teaching Authority of the Magisterium’ and ‘Revelation, Natural Law, and Homosexual Unions’, in Welch, The Presence of Christ in the Church: Explorations in Theology (Ave Maria, FL: Sapientia Press, 2012), 47–61 and 209–37. For an attempt to inscribe homosexual unions with ‘natural law’ on the grounds that they contribute to human flourishing and pertain to human nature, see Stephen J. Pope, ‘Scientific and Natural Law Analyses of Homosexuality’, Journal of Religious Ethics 29 (2001): 89–126, which suggests that new insights from ‘molecular biology, behavior genetics, neuroanatomy, and psychopharmacology’, as well as experiential data from the proliferation of recognized same-sex unions, have changed our understanding of what is natural to human beings (89–90; cf. 101 for Pope’s awareness that for Aquinas, ‘what nature “teaches” is to be determined teleologically, and teleological processes do not function uniformly … but only “for the most part”’). Welch’s ‘Revelation, Natural Law, and Homosexual Unions’ responds to Pope’s essay. See also Jean Porter, Ministers of the Law: A Natural Law Theory of Legal Authority (Grand Rapids, MI: Eerdmans, 2010), 286–87, where she defends legalizing same-sex marriage and some forms of plural marriage; and Porter, ‘The Natural Law and Innovative Forms of Marriage: A Reconsideration’, Journal of the Society of Christian Ethics 30 (2010): 79–97.

59 Brock, The Light That Binds, 234. Regarding Brock’s book, I am drawing some material from my ‘Natural Law in Bénézet Bujo, Paulinus Odozor, and Stephen L. Brock’, in Continuing the Quest for a Morality Truly Christian, Truly African: The Achievement of Paulinus Odozor, C.S.Sp., ed. Maurice Agbaw-Ebai and Matthew Levering (South Bend, IN: St. Augustine’s Press, forthcoming).

60 Pinckaers, The Sources of Christian Ethics, 420. See also Alasdair MacIntyre, ‘Intractable Moral Disagreements’, in Intractable Disputes about the Natural Law, 1–52, at 23, where MacIntyre argues for absolute moral norms as ‘a precondition for shared rational enquiry’. As Jean Porter comments, ‘Aquinas unequivocally rules out some courses of actions that might conceivably be justified by a criterion of balancing and weighing harms; for example, he insists that killing the innocent can never be morally justified, even for the sake of the common good (II-II 64.6)’ (Porter, Nature as Reason: A Thomistic Theory of the Natural Law [Grand Rapids, MI: Eerdmans, 2005], 274).

61 Finnis, Moral Absolutes, 11. Finnis adds, ‘There is never a case in which to adhere to a true specific moral absolute is thereby to “honor rules above values.” Rather, in adhering to the moral truth articulated by the “rule,” one honors the value, the person whose good in some fundamental respect one would be choosing to destroy, damage, or impede, by the act which the norm specifies as always to be excluded’ (11).

62 See François Daguet OP, ‘La nature politique chez saint Thomas d’Aquin’, Revue Thomiste 122 (2022): 211–29.

63 For discussion of this psalm, see also Haines and Fulford, Natural Law, 61–64.