Richard G. Howe | 23 April 2020 | 10 min read
Who Is Thomas Aquinas?
Thomas Aquinas (1225-1274) was a 13th century Dominican friar born in Roccasecca, Italy. He is generally considered the greatest philosopher and theologian of the middle ages. Those credentials may not necessarily convince a contemporary Protestant Christian that Aquinas’s thinking is worth considering. Why should the Christian think that philosophy of any school, Christian or otherwise, has anything to offer the Christian?
Certain categories and ideas from ancient Greek philosophy, particularly those of Plato (428-348 BC) and Aristotle (384-322 BC), have played an important role in the formulation of key Christian doctrines. It would be difficult to discuss the Trinity, the Hypostatic Union, or the Federal Headship of Adam without utilizing some of these philosophical categories. These categories not only aided in the formulation of these doctrines, but they and others also service sound philosophical thinking itself which, in turn, undergirds solid theological thinking. This is especially the case when we see how Aquinas worked with these categories and ideas, modifying and augmenting them to maximize their value for Christian thinking. It is not that there were no other important philosophical voices contributing to the philosophical and theological conversation before and after Aquinas. But I do submit for your consideration that Aquinas’s contribution stands among the most important.
An altarpiece of Thomas Aquinas in Ascoli Piceno, Italy.
Why Does Aquinas Matter?
A few key points of Aquinas’s thinking demonstrate how valuable his philosophy is for contemporary Christianity. One can find no stronger voice than Aquinas in defending sound Christian thinking on multiple issues. We shall examine three of them here: Faith and Reason; Natural Theology; and Natural Law Theory.
Faith and Reason
It is important for Christians to understand faith, reason, and the relationship between the two. There is a widespread popular misconception of faith and reason that hampers a more thoughtful Christianity. This misunderstanding can preclude meaningful and effective apologetics and evangelism.
Some erroneously understand faith as mere opinion and regard reason alone as focused on truth. For them, faith is confined to values whereas reason alone is concerned with facts. In this view, faith is entirely inner and private, is largely emotional, is expressed as feelings, and is entirely subjective; whereas reason alone addresses the outer and public, is exclusively rational, is expressed as thoughts, and alone is entirely objective. This misunderstanding forces them to relegate religion to be “true” only for one’s self and reserve reason apart from faith as dealing with that which is true for all.
In contrast, the classical view of faith and reason was expressed and defended most thoroughly by Aquinas. Since the Church Fathers, reason has been understood as accepting something on the basis of demonstration while faith has been understood as a trust in someone in a matter beyond one’s own access to or ability to understand the demonstration of the matter. It is the difference between believing on the basis of demonstration (reason) and believing something on the basis of authority.
Each of these needs to be unpacked. To illustrate, consider how two people might come to believe a particular mathematical conclusion. One may believe the conclusion to be true because he has seen and understood the mathematical demonstration of its truth (reason). In contrast, the other might not understand or be able to perform the mathematical proof, but trust the one who tells him the conclusion is true. He would be believing the conclusion on faith.
The application to Christianity is evident. While God has given humans the capacity and faculties to understand many things in creation, there are many things in creation and in God Himself that are beyond our capacities and faculties to understand. Such things we nevertheless take to be true on the basis of the authority and veracity of God who understands Himself and His creation exhaustively. Aquinas explains:
“Since man can only know the things that he does not see himself by taking them from another who does see them, and since faith is among the things we do not see, the knowledge of the objects of faith must be handed on by one who sees them himself. Now, this one is God, who perfectly comprehends Himself, and naturally sees His essence.”
Aquinas goes on:
“One who believes [i.e., has faith] gives assent to things that are proposed to him by another person, and which he himself does not see.”
The death of Jesus on the cross is a fact of history. It can be demonstrated with the tools, methods, protocols, and data arising from the discipline of history. One can know by reason that Jesus died on the cross. However, the fact that Jesus’s death on the cross is the payment for our sins is something that is revealed to us by God. No amount of human reason could demonstrate it apart from what God has told us.
This strategic understanding of the relationship of faith and reason enables Aquinas to grasp the depths and richness of a number of philosophical and theological concepts. Building upon the thinking of the Church Fathers, Aquinas argues tenaciously for reason’s ability to demonstrate the existence and attributes of God. While some theological traditions arising out of the Protestant Reformation have come to eschew this view of reason, their doing so is a departure from the Protestant tradition.
Regarding demonstrations of God’s existence, Aquinas argued that the existence of the physical world around us is sufficient to show in a number of different ways that there is a Creator God. The most famous of these demonstrations has come to be known as his “Five Ways.” Of the five, perhaps the one that has exerted the most influence is the Cosmological Argument.
Some might be surprised how Aquinas’s arguments for God’s existence demonstrate more than mere generic theism. With careful appeal to the philosophical ideas which find their origin largely in Aristotle and augmented by his own philosophical insights, Aquinas’s arguments not only demonstrate God’s existence, but also demonstrate the cherished classical attributes of God—simplicity, perfection, goodness, infinity, immutability, eternity, unity, omniscience, life, will, love, justice, mercy, providence, and omnipotence.
Exactly how Aquinas’s arguments entail these attributes would require an additional article. The philosophical doctrines that comprise Aquinas’s theistic demonstrations, when properly unpacked and arranged, go on to demonstrate these attributes. The value of this is evident. Unlike the more popular contemporary arguments that require additional arguments to flesh out the nature of the God they demonstrate, the robust nature of God is demonstrated by the philosophical doctrines that Aquinas uses.
Natural Law Theory
Natural Law Theory, (also known as common moral law) is a view about human morality, particularly in the context of human community, and morality’s connection to God. ‘Natural’ is a reference to the fact that we are humans because we possess a human nature (what theologians call the soul). It is by virtue of us having a specific human nature that we can begin to know what constitutes our good in this world as humans. It is because God has made us what we are and has made us for a purpose, that the good for us is an objective fact.
Aquinas argues that this good for us in this world is knowable by reason. Just as a person can know facts about the physical world even if he denies the God who created that world, one can know facts about the moral “world” even if he denies the God who is the ultimate accounting for that morality. Because human good in this world can be known by reason, consensus about public morality is, at least in principle, possible. One might be surprised to realize that basic principles of morality are fairly uniform throughout the world’s religions and philosophies. This is what one should expect given Paul’s teaching in Romans 2:14-15:
“For when Gentiles, who do not have the law, by nature do the things in the law, these, although not having the law, are a law to themselves, who show the work of the law written in their hearts, their conscience also bearing witness, and between themselves their thoughts accusing or else excusing them…”
To appreciate Aquinas’s thinking on Natural Law, one must see how Aquinas understands law and how Natural Law fits in the context of his three other considerations of law. He defines ‘law’ thus: “[Law] is nothing else than an ordinance of reason for the common good, made by him who has care of the community, and promulgated.” Eternal law is God’s providential working of the universe. It is the plan by which God governs His creation. Natural Law is the participation in Eternal Law by rational creatures by virtue of being rational. It is that aspect of the Eternal Law whereby the Creator governs and guides the moral actions of humans such that, when obeyed, it leads humans to their proper end in this world. This understanding of Natural Law endured into Protestantism. John Calvin (1509-1564) argued that “nothing, indeed, is more common, than for man to be sufficiently instructed in a right course of conduct by natural law, of which the Apostle here speaks [in Rom. 2:14-15].”
After Eternal Law and Natural Law is Human Law. Human Law is a particular application of Natural Law to local communities. Given that it is man’s attempt to apply the morality of the Natural Law to specific human situations, it is imperfect. Last in Aquinas’s treatment of law is Divine Law—the revelation of God’s law through Scripture to believers. Not surprisingly it overlaps with Natural Law but also contains laws and prescripts that pertain only to those who are in a saving relationship with God.
With the fall of man, it can be difficult to convince non-believers that certain actions are obligatory and others are immoral. Nevertheless, throughout history, God has used our human ability to know some aspects of morality to a sufficient degree as a means by which He guides the affairs of humans and manages the peaceful coexistence of humans within nations.
The Fresco of Thomas of Aquinas in cupola of church Basilica di San Prospero, Italy
Space does not allow for an exploration into more details regarding Faith and Reason, Natural Theology, and Natural Law Theory. Much less does space allow even the briefest treatment of other critical issues about which Aquinas has many valuable things to say, including the first principles of knowledge, the problem of skepticism, religious language, and the problem of evil. This short treatment should, however, encourage you to consider the formidable thinking of Thomas Aquinas and the contributions he can make to many contemporary philosophical, theological, and apologetical concerns.
Dolezal, James E. All That Is in God: Evangelical Theology and the Challenge of Classical Christian Theism. Grand Rapids: Reformation Heritage Books, 2017.
________. God Without Parts: Divine Simplicity and the Metaphysics of God’s Absoluteness. Eugene: Pickwick, 2011.
Feser, Edward. Aquinas: A Beginner’s Guide. Oxford: Oneword, 2010.
Geisler, Norman L. Thomas Aquinas: An Evangelical Appraisal. Grand Rapids: Baker, 1991.
Howe, Thomas. Objectivity in Biblical Interpretation. Altamont Springs: Advantage Inspirational, 2004.
Kerr, Gaven. Aquinas’s Way to God: The Proof in De Ente et Essentia. Oxford: Oxford University Press, 2015.
McInerny, Ralph. A First Glance at St. Thomas Aquinas: A Handbook for Peeping Thomists. Notre Dame: University of Notre Dame Press, 1990.
Reilly, Robert R. The Closing of the Muslim Mind: How Intellectual Suicide Created the Modern Islamist Crisis. Wilmington: ISI Books, 2010.
Veatch, Henry Babcock. Two Logics: The Conflict between Classical and Neo-Analytic Philosophy. Evanston: Northwestern University Press, 1969.
Vos, Arvin. Aquinas, Calvin, and Contemporary Protestant Thought: A Critique of Protestant Views on the Thought of Thomas Aquinas. Grand Rapids: Eerdmans, 1985.
Wilkens, Steve. Faith and Reason: Three Views. Downers Grove: IVP Academic, 2014.
The opinions and views expressed in this article are those of the author and do not necessarily reflect the views and opinions of the employees and members of Ratio Christi South Africa.
 There are several reasons why one would find more reticence to consider the thinking of Aquinas among Protestant Christians rather than Catholic Christians. First, today one will find the deliberate study of Aquinas largely confined to Catholic Christianity. As such, many Protestants might regard the ideas of Aquinas to service that tradition only and, thus, would have little to offer the Protestant Christian.
Second, Aquinas’s philosophical thinking is the apex of a classical philosophical tradition from the ancient Greeks, particularly Aristotle. Aquinas adapted the thinking of Aristotle to service Christian theology. Anyone familiar with Aristotle should find this startling on the surface. This is because Aristotle was noted by Christians as holding to many ideas that were opposed to a number of truths of Christianity including: denying there was only one God; denying that there was a creation; affirming an eternal universe; denying of any of the gods he did affirm as having any of the essential attributes of God (e.g., infinity, omnipotence; providence); and denying that humans possessed souls that survived the death of the body. It is no wonder that, given Aquinas’s heavy dependence upon Aristotle’s philosophy, just a few years after his death some of Aquinas’s teachings were condemned or judged dangerous by the ecclesiastical authorities in Paris. The effect of the Condemnation of 1277 is disputed among scholars. Many of the Dominicans and even Aquinas’s mentor and teacher Albert the Great (c. 1200-1280) continued to defend Aquinas’s teachings despite the condemnation. The condemnation itself was rescinded in 1325.
Third, this classical philosophical tradition has waned since the middle ages with the increasing influences of other philosophers from René Descartes (1596-1650) onward, not only within Christian philosophy specifically but also within western philosophy in general. As such, Aquinas’s thinking is often considered quaint and arcane with little to offer contemporary philosophical concerns. This classical tradition from the ancient Greeks up through the high middle ages stands in contrast with the now dominant philosophical approach known as analytic philosophy. Analytic philosophy is found largely within Anglo-American universities, with its origin in the early 20th century. The contrasts between the two is explored (to the end of defending the philosophical superiority of the classical tradition) in Henry Babcock Veatch, Two Logics: The Conflict between Classical and Neo-Analytic Philosophy (Evanston: Northwestern University Press, 1969).
 For example, the doctrines of the Trinity and the two natures of Christ employ the categories of nature, essence, substance, hypostasis, and subsistence (translated later with the Latin persona,from where we get the English word ‘person’ in describing the three Persons of the Trinity). Adam’s federal headship employs the category of nature and some notion of universals.
 The situation is worsened when the enemies of conservative Christianity contribute to the propagation of this misunderstanding. Most contemporary atheists completely miss how faith and reason relate in the Christian tradition. They misconstrue them by seeing an outright conflict between the two. Sam Harris sees religious faith as a menace to the human race. “Faith is the mortar that fills the cracks in the evidence and the gaps in the logic, and thus it is faith that keeps the whole terrible edifice of religious certainty still looming dangerously over our world.” [Sam Harris, The End of Faith: Religion, Terror, and the Future of Reason (New York: W. W. Norton, 2004), 232] Harris sees religious faith as “the belief in historical and metaphysical propositions without sufficient evidence” (p. 232). Harris’s worries might be justified in some contexts. There are elements of religions in the world that threaten civilization. Ironically, such contemporary dangers can be traced to the very misunderstanding of faith and reason I am exposing. For example, consider the treatment of Sunni Islam’s struggle with the relationship of faith and reason and its decision to subjugate reason to faith in Robert R. Reilly, The Closing of the Muslim Mind: How Intellectual Suicide Created the Modern Islamist Crisis (Wilmington: ISI Books, 2010).
Other atheists pile on. Richard Dawkins sees faith as “an evil precisely because it requires no justification and brooks no argument” [Richard Dawkins, The God Delusion (Boston: Haughton Mifflin, 2006), 308]. George H. Smith understands the two thus: “Reason and faith are opposite, two mutually exclusive terms: there is no reconciliation or common ground. Faith is belief without, or in spite of reason” [George H. Smith, Atheism: The Case Against God (Buffalo: Prometheus, 1979), 98]. Peter Boghossian is no less charitable. “Cases of faith are instances of pretending to know something you don’t know” [Peter Boghossian, A Manual for Creating Atheists (Durham: Pitchstone, 2013), 24].
Such erroneous views are not confined to non-Christians. The animus toward reason and any role it might play in the development of theology is a defining characteristic of the neo-orthodoxy of Karl Barth. One only has to consult the debate he had with Emil Brunner over the issue of natural theology [See Emil Brunner and Karl Barth, Natural Theology: Comprising “Nature and Grace” by Professor Dr. Emil Brunner and the Reply “No!” by Dr. Karl Barth (Eugene: Wipf and Stock: 2002)]. Even within the strong, conservative camp of Reformed thinking as expressed by the Presuppositionalists, there is a strong resistance to any notable role that reason might play in its relationship to faith. This resistance arises from their apologetic methodology. Cornelius Van Til argues, “Reason and fact cannot be brought into fruitful union with one another except upon the presupposition of the existence of God and his control over the universe.” [Cornelius Van Til, A Christian Theory of Knowledge (Phillipsburg: Presbyterian and Reformed Publishing, 1975), 18]. Jason Lisle is even more pointed. Though attempting to defend a friendly relationship between the two, Lisle nevertheless evacuated reason of all its proper role by saying “faith is a prerequisite for reason” [Jason Lisle, “Faith and Reason,” https://answersingenesis.org/apologetics/faith-vs-reason/, accessed 09/22/17]. It is evident that Lisle misunderstands faith when he likens our allegiance to the laws of logic as an expression of faith. “In order to reason about anything, we must have faith that there are laws of logic which correctly prescribe the correct chain of reasoning. Since laws of logic cannot be observed with the senses, our confidence in them is a type of faith” [Lisle, “Faith and Reason”].
Perhaps the most recent assault on reason (and by implication, on facts and faith) comes from Postmodernism. Rebert E. Webber, in his misreading of intellectual history, argues, “In the twenty-first century world… the new attitude… is that the use of reason and science to prove or disprove a fact is questionable… This… points… to the postmodern conclusion that we deal with ‘interpreted facts.’ … In the postmodern world, both believers and nonbelievers are people of faith” [Robert E. Webber, The Younger Evangelicals: Facing the Challenges of the New World (Grand Rapids: Baker, 2002), 84].
 Consider Andrew Wiles’ solving one of the longest enduring mathematical enigmas in the history of mathematics—Fermat’s Last Theorem. In personal conversation, Oxford mathematician John Lennox told me that there were very few mathematicians in the world who could understand Wile’s proof. Since I trust Andrew Wiles in light of the fact that I cannot understand the proof, I am taking it on “faith” that Fermat’s Last Theorem is true.
 Thomas Aquinas, Summa Contra Gentiles, 3, 154 , trans. Vernon J. Bourke, (Notre Dame: University of Notre Dame Press), 239.
 Thomas Aquinas, Truth, QXIV, Art. 9, reply, trans. James V. McGlynn (Indianapolis: Hackett, 1994), 249-250. Aquinas is faithful to the tradition of Augustine (354-430 AD) who said, “For who cannot see that thinking [reason] is prior to believing [faith]? For no one believes anything unless he has first thought that it is to be believed” [Augustine, On the Predestination of the Saints, 5, available at http://www.newadvent.org/fathers/15121.htm, accessed Jan. 29, 2020].
Such a view of the relationship of faith and reason endured beyond the middle ages and into the Protestant Reformation. In defending the role of reason in the confirmation of our faith, the Puritan John Owen (1616-1683) observed, “There are sundry cogent arguments, which are taken from external considerations of the Scripture, that evince it on rational grounds to be from God… and… are… necessary unto the confirmation of our faith herein against temptations, oppositions, and objections” [John Owen, “The Reason of Faith,” in The Works of John Owen, vol. 4 (Edinburgh: The Banner of Truth Trust, 1967), 20]. The Puritan Stephen Charnock (1628-1680) displayed the same sentiment. “Men that will not listen to Scripture… cannot easily deny natural reason… There is a natural as well as a revealed knowledge, and the book of the creatures is legible in declaring the being of a God…” [Stephen Charnock, Discourses upon the Existence and Attributes of God (Grand Rapids: Baker, 1979), 27]. Charnock goes on: “God in regard of his existence is not only the discovery of faith, but of reason. God hath revealed not only his being, but some sparks of his eternal power and godhead in his works, as well as in his word… It is a discovery of our reason… and an object of our faith… it is an article of our faith and an article of our reason” [Discourses, p. 27].
 A key point to bear in mind is that, while Christians believe in certain things because we take them to be told to us by God, we need only do so because reason is able to demonstrate that God exists, that He is omniscient and good, that He never lies, and that the Bible is His inspired and inerrant word. Critics of Christianity throughout history often have failed to see this point, viz, that Christianity maintains that the objects of faith can be confidently taken on faith because reason has demonstrated the authority of God and His revelation of Himself through His Prophets, and Apostles, and His Son, the Lord Jesus.
 Thomas Aquinas, Summa Theologiae, I, Q2, art. 3.
 In many ways, contemporary versions of the theistic arguments avoid appealing to the specific philosophical notions that Aquinas employs in his arguments. Instead, the contemporary versions most often appeal to the data arising from contemporary science. By doing so, what they gain in popular appeal, they lose in philosophical cogency. For a treatment of the specifics of Aquinas’s versions in their original philosophical context, see Edward Feser, Aquinas: A Beginner’s Guide (Oxford: Oneworld, 2010);The Last Superstition: A Refutation of the New Atheism (South Bend: St. Augustine’s Press, 2008); Five Proofs of the Existence of God: Aristotle, Plotinus, Augustine, Aquinas, Leibniz (San Francisco: St. Ignatus, 2017); Matt Fradd and Robert Delfino, Does God Exist? A Socratic Dialogue on the Five Ways of Thomas Aquinas (St. Louis: Enroute, 2018); Gaven Kerr, Aquinas’s Way to God: The Proof in De Ente et Essentia (Oxford: Oxford University Press, 2015); and Joseph Owens, “Aquinas and the Five Ways,” Monist 58 (Jan. 1974): 16-35.
 The accusation that this classical approach cannot deliver any more than a generic theism is common among Presuppositionalists due to their misunderstanding of Aquinas’s philosophy. Van Til said, “[The natural man] has constructed such proofs. But the god whose existence he proves to himself in this way is always a god who is something other than the self-contained ontological trinity of Scripture” [Cornelius Van Til, Common Grace and the Gospel (n.c.: Presbyterian and Reformed, 1974), 190]. K. Scott Oliphint levels the same criticism. “The goal isn’t to argue for, or otherwise endorse, a generic theism—as Thomistic (i.e., Thomas Aquinas-influenced) apologetics wants to do. Rather, the goal is to show the utter inescapability of Christian truth. … The problem with unbelief is not its theism (or lack thereof), but its steadfast refusal to acknowledge the true God, who is known. The best way to argue that point is with the whole counsel of God—not by moving people to acknowledge some generic ‘something, somewhere’ that’s probably out there and bigger than we are” [K. Scott Oliphint, “Reason for Your Hope: Scott Oliphint on a Fresh Approach,” at https://www.thegospelcoalition.org/article/reason-hope/, accessed February 2, 2020].
 Having demonstrated the existence of God in Q2 of his Summa Theologiae, Aquinas goes on to demonstrate God’s simplicity, i.e., the doctrine that God is in no way composed of parts. Aquinas then shows how the classical attributes of God cascade inexorably from simplicity. For a treatment of how God’s simplicity entails all these superlative attributes, see Richard G. Howe, “Antecedents to Aquinas’s Doctrine of Simplicity” available at http://richardghowe.com/index_htm_files/AntecedentstoAquinasDoctrineofSimplicityWebVersion.pdf, accessed July 2, 2020. For a fuller treatment of simplicity, see James E. Dolezal, God Without Parts: Divine Simplicity and the Metaphysics of God’s Absoluteness (Eugene: Pickwick, 2011). For a fuller exploration and defense of the classical attributes, see James E. Dolezal, All That Is in God: Evangelical Theology and the Challenge of Classical Christian Theism (Grand Rapids: Reformation Heritage Books, 2017).
 These philosophical doctrines would include (without making any effort to explain each of them here): act/potency; form/matter; efficient, formal, material, and final causality; exemplar causality; analogy of being; existence; the essence/existence distinction; and the Transcendentals.
 For a discussion of Natural Law Theory, see J. Budziszewski, Written on the Heart: The Case for Natural Law (Downers Grove: InterVarsity, 1997).
 New King James Version (Nashville: Thomas Nelson, 1982). For a discussion of public morality and the common moral law, see Norman Geisler and Frank Turek, Legislating Morality (Minneapolis: Bethany House Publishers, 1998) republished, (Eugene: Wipf and Stock, 2003).
 Thomas Aquinas, Summa Theologiae, I-II, Q. 90, art. 4, St. Thomas Aquinas Summa Theologica: Complete English Edition in Five Volumes, trans. the Fathers of the English Dominican Province (Westminster, MD: Christian Classics, 1981). All quotations of the Summa Theologiae are from this translation unless otherwise indicated.
 “It is evident, granted that the world is ruled by Divine Providence… that the whole community of the universe is governed by Divine Reason. Wherefore the very Idea of the government of things in God the Ruler of the universe, has the nature of a law. And since the Divine Reason’s conception of things is not subject to time but is eternal, according to Prov. viii, 23, therefore it is that this kind of law must be called eternal” [Thomas Aquinas, Summa Theologiae, I-II, Q. 91, art. 1].
 “It is evident 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. Now among all others, the rational creature is subject to Divine providence in the most excellent way, in so far as it partakes of a share of providence, by being provident both for itself and for others. Wherefore it has a share of the Eternal Reason, whereby it has a natural inclination to its proper act and end: and this participation of the eternal law in the rational creature is called the natural law” [Thomas Aquinas, Summa Theologiae, I-II, Q. 91, art. 2].
 John Calvin, Institutes of the Christian Religion, 2 vols. trans. Henry Beveridge (Grand Rapids: Wm. B. Eerdmans, 1975), Bk. II, Chap. 2, §22, p. 241. Calvin goes on: “Since man is by nature a social animal, he is disposed, from natural instinct, to cherish and preserve society; and accordingly, we see that the minds of all men have impressions of civil order and honesty. Hence it is that every individual understands how human societies must be regulated by laws, and also is able to comprehend the principles of those laws. Hence the universal agreement in regard to such subjects, both among nations and individuals, the seeds of them being implanted in the breasts of all without a teacher or lawgiver… It is true, that some principle of civil order is impressed on all. And this is ample proof that, in regard to the constitution of the present life, no man is devoid of the light of reason” [Institutes, Bk. II, §13, pp. 234-235]. For more on Natural Law thinking within Reformed theology, see David VanDrunen, Divine Covenants and the Moral Order: A Biblical Theology of Natural Law (Grand Rapids: William B. Eerdmans, 2014); “Medieval Natural Law and the Reformation: A Comparison of Aquinas and Calvin,” American Catholic Philosophical Quarterly 80 (2006): 77-98; and Stephen J. Grabill, Rediscovering the Natural Law in Reformed Theological Ethics (Grand Rapids: William B. Eerdmans, 2006).
 “It is from the precepts of the natural law, as from general and indemonstrable principles, that the human reason needs to proceed to the more particular determinations of certain matters… Wherefore human laws cannot have that inerrancy that belongs to the demonstrated conclusions of sciences” [Thomas Aquinas, Summa Theologiae, I-II, Q. 91, art. 3, ad. 3].
 “It was necessary for the directing of human conduct to have a Divine law… If man were ordained to no other end than that which is proportionate to his natural faculty, there would be no need for man to have any further direction on the part of his reason, besides the natural law and human law … But since man is ordained to an end of eternal happiness which is inproportionate to man’s natural faculty… it was necessary that, besides the natural and the human law, man should be directed to his end by a law given by God” [Thomas Aquinas, Summa Theologiae, I-II, Q. 91, art. 4].