Perhaps the most drastic intellectual change of the past four hundred years has been the dominance of the empirical scientific method. However, along with the rise of this remarkably effective and transformative method of interacting with the physical world has come several ideologies incompatible with the Catholic faith. Vatican I stated that naturalism, understood as the rejection of all supernatural causality, strikes at the heart of the Christian belief in the supernatural establishment of the Church. The various miracles of Scripture, including the Incarnation and the Resurrection of Jesus Christ, as well as the divine inspiration of Scripture, are denied by this ideology.

This article will explore the facets of miracles that are relevant to the interaction between Catholicism and the natural sciences, showing that the compatibility between faith, reason, and the sciences requires that the scientific method be open to exceptions in laws of nature. This is, surprisingly, something science is already structured to accept without disruption to the contemporary scientific process. This topic stands at the intersection of faith and reason, inquiring as to the rational credibility of the supernatural claims of the Catholic faith. The faithful theologian is able both to exert the full scope of natural reason and to wonder at the supernatural revelation of God which is above merely human action. It is clear that within the scientific method is an opening for reason to receive the supernatural.

I. Miracles in Scripture and the Magisterium: Signs of Divinity and Encouragement of Belief

The Catechism of the Catholic Church states that the fundamental character of miracles in Scripture is to “manifest that the kingdom [of God] is present in [Jesus Christ] and to attest that he was the promised Messiah” (CCC no. 547). The Synoptic Gospels (i.e., Matthew, Mark, and Luke) show the many healings and miracles of Christ driving out earthly evils as signs of Christ’s mission to drive out spiritual evils and defeat the kingdom of Satan (CCC no. 549, 550; Mt 11:5, 12:26–28; Mk 5:25–34; Lk 7:17-28, 12:13–14, 19:8). The Gospel of John, itself structured by the great miracle-signs that Jesus performs, continues all of these themes. The miracles connect faith in Jesus’ divine mission from the Father to the eternal life that He offers, culminating in raising Lazarus from the dead. This foreshadows the Paschal Mystery in which Jesus would give eternal life to all through His own death and resurrection (CCC no. 547, 550; Jn 5:36, 6:5–15, 8:34–36, 10:25, 10:31–38, 12:31, 18:36). This connection between miracles and eternal life is particularly evident in the feeding of the multitude and the Bread of Life discourse (CCC no. 1335; Jn 6:1–71). The miracles of Christ in Scripture are divine aids which help the faithful believe in the divinity and Messianic mission of Jesus Christ and which are also connected to redemption and the regeneration of the soul in the sacraments. The Book of Acts shows how the apostles and other disciples of Jesus continued his ministry through miraculous healings and other miracles of the Holy Spirit, contributing to the credibility of the Church as endowed with divine help (CCC no. 156, 434; Acts 3:1–11, 5:1–21, 6:8, 8:5–8, etc.).

In addition to their central place in Scripture, miracles are spoken of by six ecumenical councils: Ephesus, Constantinople II, Constantinople III, Trent, Vatican I, and Vatican II. The Council of Ephesus mentions the miracles of Christ in its discussion of the divinity of Christ, saying that “because he used his own Spirit to display his godhead (θεότητος, deitatis) through his mighty works (μεγαλουργίας, mira opera).”{1} Following that, in the ninth canon of the letter, it states:

If anyone says that the one Lord Jesus Christ was glorified by the Spirit, as making use of an alien power (ἀλλοτρίᾳ δυνάμει, aliena virtute) that worked through him and as having received from him the power to master unclean spirits and to work divine wonders (τάς θεοσημείας, divina signa) among people and does not rather say that it was his own proper Spirit through whom he worked the divine wonders (τάς θεοσημείας, signa), let him be anathema.{2}

While the Council of Ephesus was concerned with the proper power of Christ rather than one from another working miracles, it affirms the previous statement that the Lord Jesus worked miracles. The purpose here is to show that what was displayed was in fact Christ’s proper divine power working miracles, not a delegated power. Theologically, this is not only important for reaffirming the divinity of Christ, but also for upholding the first major theological principle of miracles: that only God can work authentic miracles. The Second and Third Councils of Constantinople reinforce that it is the same Word of God which works miracles (in these cases θαυματουργήσαντα and θαύματα, respectively).{3} We will explore this principle later when speaking about the metaphysics of miracles.

The Council of Ephesus and the Council of Trent also speak about miracles as worked by God in the saints. Ephesus makes a passing reference to the miracles, saying that the Holy Spirit worked “miracles (παράδοξα) through the hands of the apostles.”{4} This reinforces the ultimate source of miracles and distinguishes the wonders God works in the apostles from the divine signs God works in His own human nature through His own proper, divine spirit. The created human nature inseparably united to the divine Person of the Son is not the source of the miraculous action but is elevated to receive it; the divine nature works miracles in the finite human nature of Jesus Christ.

The Council of Trent speaks about the miracles of the saints in the decree on The Invocation, Veneration, and Relics of the Saints, and on Sacred Images, of the twenty-fifth session.{5} In addition to reiterating Lateran IV’s prohibition on new veneration of relics or images without episcopal and papal approval, Trent gives a reason why the miracles of the saints ought to be public in the Church:

Bishops should teach with care . . . that great benefits flow from all sacred images, not only because people are reminded of the gifts and blessings conferred on us by Christ, but because the miracles (miracula) of God through the saints and their salutary example is put before the eyes of the faithful, who can thank God for them, shape their own lives and conduct in imitation of the saints, and be aroused to adore and love God and to practise [sic] devotion.{6}

As this decree indicates, miracles are clearly intended as a sign of God and serve to increase the devotion of the faithful. Miracles are inspirations for love and good works and stand as reminders for the faithful to recenter their focus on God and a holy life. They are not a distraction from it, as some iconoclastic strains of early Protestantism claimed. Again, miracles are acts of God through the saints (per sanctos) rather than acts of saints on their own power (something impossible). The magisterium of the Church is clear that miracles are acts of God, even if God works them through created instruments.

Countering a different threat, the First Vatican Council taught that both faith and reason have their roles in demonstrating God’s providence in the universe. The Dogmatic Constitution on the Catholic Faith Dei Filius is the most important magisterial document written on miracles. It was written at a time when post-Kantian German Idealism had heavily affected Catholic theology in Europe at large and Germany in particular. The Council identified the major error responsible for the endemic problems in Christian theology as

the doctrine of rationalism or naturalism, which is completely opposed to the Christian religion, as its origin is supernatural, and it strives above all that Christ, who is our Lord and Savior, be excluded from human minds, from the life and customs of peoples, that the reign of what they call “pure reason” or “nature” may be established. Thus, with the abandonment of the Christian religion, the rejection of the true God and his Christ, the mind of many has fallen into the abyss of pantheism, materialism, and atheism, so that natural reason itself, denying all just and right laws, destroying the deepest foundations of human society.{7}

Vatican I pointed to the denial of the supernatural and the accompanying exaltation of “pure reason” as the root causes of pantheism, materialism, and atheism. Without getting too bogged down in historical minutiae, the post-Kantian German Idealist influences held that God was a response to the necessity of human reason as a regulating principle, and therefore there was no possible way of knowing whether God really existed in the world outside of human reason. Coupled with this was an insistence that the laws of nature as observed by the sciences were also necessary laws of human reason, leading to an identification of the rational order of the world with God and human consciousness. These positions left no room for the theologian to know with certainty that God existed outside of the mind or whether God was free to create since these philosophers believed that it was impossible to disentangle God, the world, and the human mind from each other.

Because Jesus Christ is acknowledged by all parties to be a matter of historical contingency (i.e., that it was possible for the Incarnation not to have occurred), these philosophers denied that God became human in order to save humanity in one historical event. They believed it would be irrational for God to hang what is necessary for all human beings on an historical contingency that could not be proven by reason.

It is thus clear why the Council taught that naturalism (i.e., the denial that there can be more than natural causes in the world) was the cause of pantheism, materialism, atheism, and the denial of Christianity. These philosophers’ God-mind-world tangle resulted in three erroneous conclusions: pantheism (the world and its laws are God), materialism and atheism (God is merely a mental construct that could be denied), or denial of Christianity (the saving Incarnation is irrational). The roots of these errors lie in the doubt that human beings can, through reason, know anything about God and in an unfounded exaltation of the “laws of nature,” by which they meant a peculiar interpretation of the physical sciences.

We will return to the laws of nature below, but we must first explore important truths established by Vatican I and in other articles in this encyclopedia.{8} The first, which we shall not further explore here, is that human beings “are able to know with certainty” the existence of God, and that God is the source and end of all things, “by the natural light of human reason.”{9} The second is that God is almighty, eternal, unchangeable, and freely creates all things out of His goodness and not out of any constraint or need. The third is that, though faith is a gift of the Holy Spirit, it pleased God to confirm the act of faith and assist divine revelation through external signs (argumenta), “namely divine deeds, in the first place miracles and prophecies, by which, clearly showing forth the infinite power and wisdom of God, the signs (signa) of divine revelation are most certain and accommodated to all intelligences.”{11}

The corresponding canons to this chapter in Dei Filius pastorally bind Catholics to believe that miracles are possible and that the miracles of Scripture occurred: “If anyone says that miracles are impossible and that all stories of them, even contained in Scripture, are to be read as fables or myths, or that miracles can never be known with certainty, and that it is not by them that the divine origin of the Christian religion is rightfully proven, let him be anathema.” {12}

Vatican I was quite insistent that human reason can know God and that the sciences, philosophy, or other exercises of human reason cannot contradict divine revelation. Since God is the source both of divine revelation and of the light of human reason, human reason can never truly contradict divine revelation, or God would be denying Himself. “Truth cannot contradict truth.”{13} Any apparent contradiction has its source either in a misunderstanding of the teachings of the Church or in mere opinion being treated as though it is the certain conclusion of reason.{14} Thus, Catholics cannot hold that an apparent conclusion from philosophy or the sciences is true when that conclusion contradicts the proper understanding of divine revelation or dogma. Instead, while supporting the development of the arts and sciences, Catholics must show that conclusions from the sciences or philosophy are merely probable, whereas revelation is certain. When understood in this way, the sciences and a proper understanding of revelation and dogma will reinforce each other, the sciences providing truth and matter for reflection in light of revelation. If this harmony does not occur, then the cause of the dissonance is a defect either in one’s understanding of the Catholic faith or in the arguments of reason and the sciences. Following Dei Filius, much of theology-science dialogue is dedicated to clarifying understandings of either the Catholic faith or of the sciences in order to eliminate apparent contradictions. While this may be difficult at times, it is incumbent upon the Catholic interested in faith and science to hold to the fundamental compatibility and mutual support of faith and reason, even in apparent difficulties such as miracles.

Finally, the Second Vatican Council speaks of the miracles of Christ in two places: Dei Verbum and Dignitatis humanae. The Dogmatic Constitution on Divine Revelation Dei Verbum mentions the signs and miracles (signis et miraculis) of Christ, the Word made flesh, as a testimony of His manifestation of the Father and the mission of the Spirit of truth.{15} These miracles and signs, along with the Resurrection and the entire Paschal mystery, show the divine confirmation of the acts of Jesus Christ, not merely as a human being, but as the second Person of the Trinity, revealing the Father and the Spirit.

In the Declaration on Religious Freedom Dignitatis humanae, the Council also mentions the miracles of Christ, this time in the context of the subjective response to such miracles. Speaking in the context of the necessity of a free and voluntary act of faith, the Council states:

For Christ, who is our master and lord, but also is gentle and humble of heart, patiently attracted and invited his disciples. Certainly he illuminated and confirmed his teaching with miracles, to stir up and strengthen the faith of his hearers, though not to exert pressure on them.{16}

Here, Vatican II combines the confirmation of miracles in Dei Verbum and Dei Filius with the subjective dispositions of Trent’s treatment of miracles to make a synthesis of the assertion that miracles encourage a free act of faith. Though, as Dei Filius taught, miracles are an external confirmation of the reliability of what the internal act of faith accepts, the act of faith is inherently free and cannot be coerced. This gift of the Holy Spirit must be accepted freely. When it is freely accepted, it gives certainty as to the divinity of the source of the message.

Each of the ecumenical councils which taught about miracles asserts that miracles exist for the sake of manifesting the revelation of God and for encouraging the faithful to trust in that message. Miracles play an important role in reminding the faithful of the supernatural character of their faith and of the wondrous deeds of God, deeds which cannot be contained by the merely natural or physical. Thus, we next turn to an important question that uses the natural sciences as its inspiration: whether contemporary, scientifically minded people can accept that God can work miracles at all. If miracles are so important to the confirmation of the message of divine revelation and in manifesting the divinity of Christ, then the interaction between miracles and the natural sciences is one of chief importance in understanding God’s supernatural interactions with the created world.

II. Philosophical Issues Regarding Miracles and the Natural Sciences: David Hume and the Laws of Nature

With the significative dimension of miracles firmly established as a preeminent mode of credibility for the divinity of Jesus Christ and divine revelation, one major line of argument from modern philosophy must be considered. David Hume, an eighteenth-century Scottish agnostic, famously argued against the credibility of miracles in any context. His argument against miracles sheds light not only on the modern understanding of miracles and the accompanying Christian response, but also on some very common ideas of the contemporary natural sciences which must be addressed. Hume’s argument is as follows:

A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined. . . . There must, therefore, be a uniform experience against every miraculous event, otherwise the event would not merit that appellation. And as an uniform experience amounts to a proof, there is here a direct and full proof (emphasis original), from the nature of the fact, against the existence of any miracle; nor can such a proof be destroyed, or the miracle rendered credible, but by an opposite proof, which is superior.

The plain consequence is (and it is a general maxim worthy of our attention), “That no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish: And even in that case there is a mutual destruction of arguments, and the superior only gives us an assurance suitable to that degree of force, which remains, after deducting the inferior.”{17}

Hume’s argument is that a miracle, being a violation of a law of nature established by long experience, can never be established as more likely than the normal course of nature. Hume goes on to show that, no matter how robust the witness of a miracle is (and Hume doubts that there have been any truly well-attested miracles), the unbroken testimony of experience will always make it more likely that the witnesses were mistaken, insufficiently informed regarding the sciences, credulous, lying, or involved in a forgery of the supernatural.{18} Since natural occurrences are so likely, and experience has so recommended the occurrences that happen together such that they constitute a law, then it is always more likely for the effect described by the law to happen than for it to be violated by a miracle. It thus follows that no matter how reliable human testimony is to the alleged occurrence, it is always more rational to believe that the course of nature has followed as it always has.

There are two major ideas in Hume’s argument that are particularly important to the Catholic theologian. The first is the question of probabilistic testimony. Since miracles are contingent historical actions of God, they cannot be proven through deductive reasoning. They did not have to occur but occur because of God’s will. Therefore, the testimony of the miracle is how the veracity of the miracle is established. Second, and much more influential to contemporary conversations, is the question of what a law of nature is and the nature of its role in the natural sciences.

A. Cardinal Newman and Bayesian Probability

St. John Henry Cardinal Newman, now a doctor of the Church, wrote two essays on miracles: On Biblical Miracles (1825–1826) and On Ecclesiastical Miracles (1843–1844).{19} In these essays, he explicitly engages Hume and other skeptics like Jeremy Bentham.{20} Newman deploys an important philosophical and statistical clarification of Hume by introducing the category of antecedent probability, first articulated by Thomas Bayes in a posthumous essay of 1763.{21} Antecedent probability is the likelihood that an event is to happen without factoring in the specific conditions of the particular experiment or situation. In current experimental methods, this is often called the probability of the null hypothesis: the likelihood that the event would happen without specific experimental intervention.{22} Newman argues that, “facts are only so far improbable as they fall under no general rule; whereas it is part of an existing system that the Miracles of Scripture demand our attention, as resulting from the known attributes of God, and corresponding to the ordinary arrangements of His providence.”{23} Newman argues, first as a Protestant, that the miracles of Scripture are a part of the extensive moral order of God, urging the people of God toward Him as final cause, thus making Biblical miracles part of a preexisting pattern of divine action and raising their likelihood when connected with such revelatory events.{24} Newman continues this analysis of antecedent probability in relation to ecclesiastical miracles in the throes of his journey to Catholicism. As we saw in the explicit treatment of the Magisterium above and again below, the significative aspect of miracles is a core purpose of miracles and, given a belief in God as supreme governor of the universe, miracles become much more likely.

For the purposes of answering Hume, the difference between antecedent probability and consequent probability is a principled and reasonable distinction, not just for miracles but for any unlikely event. It is extremely unlikely for any given individual to be struck by lightning or to win the lottery. There indeed ought to be evidence brought to support such an extraordinary claim. However, factoring in evidence of, for instance, burns or a hospital stay or a novelty check, the consequent probability of such extraordinary occurrences can become quite high. The testimony of experience without investigation of the concrete circumstances would exclude someone being struck by lightning or winning the lottery from one’s neighborhood, but there is indeed a possibility that such an occurrence would happen. In light of the evidence, such an unlikely event might become very likely to have occurred, and to exclude this possibility ahead of time would be an abuse of statistical reasoning.

In such cases, the difference between antecedent and consequent probability could be compared to the probability of the null hypothesis versus the likelihood that the evidence supports the experimental hypothesis in the experimental sciences. If there is a significant difference between the support for the experimental hypothesis and the null hypothesis, then it is a successful experiment, showing that there is an effect when predicted, not something to be excluded on the grounds that the experimental hypothesis is unlikely. Therefore, Hume’s exclusion of an unlikely event does not respect the role that evidence can play in establishing the unlikely nature of an event.

B. Laws of Nature and Laws of Science

Of course, the second argument against miracles in Hume’s account is the idea of a law of nature. Hume’s argument relies on the fact that, not only is reliable testimony extraordinarily unlikely, but that it is never more likely that testimony will be found that is so reliable as to indicate a violation of a law of nature. We will explore a few major distinctions concerning what a law of nature is, but Hume’s argument relies on the fact that there is “uniform experience against every miraculous event, otherwise the event would not merit that appellation.” The implication is that the ways in which we observe the universe operate never change or admit exception. “The ways in which the universe operates” is a fair definition of the laws of nature. These laws can be treated in two ways: either they are merely descriptions of what we observe, or they are prescriptive of what the universe must obey. If they are merely descriptive, then the Humean view is begging the question, assuming that there has never been any experience of a miracle and therefore they do not happen. If the laws of nature are prescriptive, then there is a belief that the universe cannot do anything other than the way it does operate. In this case, miracles would also be excluded on the grounds that it is impossible for the universe to allow them.

There is a distinction between how the universe actually operates and scientific laws as statistically established by experimentation. Many scientists and philosophers have assumed the philosophical presupposition of naturalism or determinism, in this case meaning that there can never be a violation of the laws of nature. Our distinction concerns the difference between the laws of nature and the laws of science. What is the difference between how the universe operates and what scientific experiments inform us? Scientific procedure in collecting data and abstracting statistical generalities from them is very different in practice than an Enlightenment presupposition that the universe always strictly obeys mathematical laws. In actual experimental observation, it is almost never the case that an experiment produces data which perfectly fit the expected statistical abstraction. Between factors of observational error or uncontrolled variables not anticipated by the experiment, the actual observed data are almost always in “violation” of those strict regularities of the universe held by the Enlightenment presupposition of inviolable laws of nature. The statistical generalities abstracted from data always account for the messiness of actual scientific experiments and so represent a generalized idealization. This is not found in any particular experiment but developed from generalizations from many different data sets. Individual data points can be in violation of the general statistical trends and not undermine the law established statistically.

The distinction between the laws of nature on the one hand and statistically generated laws of science on the other expose a major presupposition of the Humean opposition to miracles. Those who oppose miracles on the grounds that they do not conform to scientific laws assume that the laws of science are as inviolable as they assume the laws of nature to be. The laws of science, in actual scientific practice, however, are constantly “violated” by small portions of non-conforming experimental data without ever being broken by these exceptions. This is because they are statistically capable of incorporating them into a general trend. The Enlightenment presupposition that the laws of nature (i.e., the way the universe actually operates) are regular and inviolable is not supported by scientific practice and is a mere assertion of a philosophical ideal. As the sciences themselves show, it is not in fact supported by observation and experience. The Humean approach to the inviolability of laws of nature does not have robust support either from reasoning or from the sciences, and so this distinction between the laws of nature and the laws of science forces us to explore more aspects of miracles and the natural sciences. It particularly forces us to ask how a Christian can investigate a miracle and still hold to the efficacy of the physical sciences.

A corollary to this distinction between the laws of nature and the laws of science is echoed in many treatments of miracles from St. Augustine to the present: that miracles are comparatively rare. St. Augustine’s influential definition of a miracle is “something difficult and unusual, and exceeding the expectation and ability of those who wonder at it.”{25} While we will revisit a version of this definition when treating the theology of St. Thomas Aquinas on miracles, it is notable that miracles being unusual are a core part of the definition. Miracles do not occur as frequently as other events in nature and are therefore the exception to the rule. They are not rules in their own right. If a miracle is rare, it will not interfere with the statistical generation of scientific laws, which exclude any datum outside of appropriate standard deviations as outliers in the experiment. The ability to exclude outliers in scientific statistics and the definitional rarity of miracles ensure that miracles do not upset the current methods of the physical sciences.

III. Theological Approaches to Miracles and the Natural Sciences from the Thought of St. Thomas Aquinas

The writings of St. Thomas Aquinas can be quite helpful in answering this question of the compatibility of miracles and the natural sciences, especially in understanding the picture of metaphysical issues at play.{26} As a doctor of the Church, St. Thomas has been praised by various popes as a trustworthy guide, and his thought can guide Catholics seeking to pursue a synthesis of the sciences, reason, and faith.{27} There are other approaches to scriptural miracles in the history of the Church, such as the approach of St. John Henry Cardinal Newman outlined above, but St. Thomas’s approach develops earlier Augustinian traditions into a metaphysical, natures-based approach and is very helpful when applied to the contemporary sciences.

A. Metaphysical Criteria for Miracles

St. Thomas Aquinas defined miracles as “something difficult and unusual, above the ability of nature, and exceeding the expectation of those who see it, provoking wonder.”{28} Whereas St. Augustine defined miracles on the basis of wonder, St. Thomas adds the criterion of exceeding the ability of the nature of the creature God has moved to miraculous action. This criterion requires a certain knowledge of the metaphysical nature of creatures (i.e., the fundamental structure that makes its causal powers and abilities what they are) to determine whether a given action does in fact exceed the abilities of the creature’s nature.

Of course, God’s providence orders and arranges all things, even those things which are extremely unlikely. While popular parlance might hold that some extraordinary events are miracles (like the “miracle on the Hudson” in which a plane landed safely on the Hudson River), for St. Thomas and as the Magisterium implies, miracles are done by supernatural power; it is not sufficient for a merely providential but naturally possible event to occur. Even if God works a miracle that would be possible to happen naturally, God does work miracles directly (i.e., without using creatures as his instruments). St. Thomas Aquinas uses the example of curing a man of a fever to illustrate this kind of miracle.{29} While it is possible to cure a man of a fever by natural means, such as giving him medicine, it is possible for God to instantly and miraculously heal the man without using natural means.{30} If God providentially arranges for a doctor with appropriate medicine to walk through the door at that very moment, such an arrangement would still be an act of God, but it would not be a miracle because God is working through natural means. God’s miracles move creatures to act beyond their natural capacities, either in themselves or as they are moved through others. A miracle, therefore, involves God moving creatures to act in ways they could not normally act, either by themselves or through other creatures, without an intermediary.

a. Preternatural and Supernatural Action

At this point, a clarification concerning the Church’s classic distinction between the different kinds of actions above a created nature is in order. With the Patristic and medieval interpretations of the fall of humanity in the background, the Council of Trent declared that death came upon humanity as a result of the Fall, causing humanity to lose the gifts of “holiness and justice” bestowed on them by God.{31} In the condemnation of Michael Bays in 1567 and in the condemnation of the Synod of Pistoia in 1794, Popes Pius V and Pius VI clarified that immortality was in fact a gratuitous gift of God which exceeded the natural condition of human nature.{32} Death, therefore, was a punishment for and effect of original sin. God withdrew His gifts of holiness and justice, which kept the body and soul in harmony with each other while seeking God’s will before the Fall.

These gifts, bestowed beyond and above human nature, have classically been called “preternatural” by theologians, deriving from the words praeter, meaning “beyond” and natura, meaning “nature.” The preternatural gifts of immortality and integrity, lost by the Fall, were special gifts of God beyond human nature. The category of a gift beyond a creature’s nature came into Catholic theology from this reflection on prelapsarian humanity and is the fundamental metaphysical approach to miracles.

According to Catholic theology, in miracles, God, by preternatural action, moves creatures to act beyond their natures. This is normally distinguished from what is called supernatural action. Supernatural action is accomplished through divine grace, which transforms the soul and makes it capable of cooperating with divine power.{33} This grace is given by God and infused into the soul, transforming the Christian into a child of God. While it does not effect a complete change of one substance into another, sanctifying and sacramental grace does change human beings and makes them able to operate by the grace which abides within them.

The important distinguishing factor between preternatural action and supernatural action is that, in preternatural action, God directly moves and continually sustains by an act of divine power, whereas in supernatural action God changes the created nature, bestowing a quasi-nature or quasi-faculty on the creature, who is now able to act beyond its natural limits. In other words, preternatural action is not due to an indwelling of divine power but is a special gift. Supernatural action is due to an indwelling of divine power which changes the creature by means of a special gift of grace. Causing the waters of the Red Sea to stand like a wall and defy gravity, multiplying the loaves and fishes, and healing blindness by means of spit and earth are all examples of preternatural action, which elevates the creature to do what it could not alone. It does not, however, transform the nature of the creature to perform these actions from their own interior causality. Supernatural actions are possible because of the transformations effected through the infusions of a new sacramental character in Baptism, Confirmation, and Holy Orders. Baptism allows the Christian to receive grace and act by it. All meritorious actions are supernatural because they are accomplished through God’s divine life of grace but also by virtue of their supernatural character. The seal of the sacrament of Confirmation and the promptings of the Holy Spirit endow confirmed Christians with a special attentiveness to the gifts of the Holy Spirit. The sacramental character of the priesthood allows the priest to forgive sins or consecrate the Eucharist. It is God doing these things, but God is doing these things through the sacramental character indelibly marked on the priest at his ordination.

While supernatural action describes actions such as the sacraments, certain aspects of Christian life (e.g., the meritorious actions of the Christian, divine grace in the soul, and the Beatific Vision,) are not “unusual,” as the definition of a miracle has it, but normal. Because there is a change in the nature of the created thing and the new action happens by means of a new quasi-faculty of that nature, there are regular and predictable ways in which the creature can act beyond its natural abilities precisely by virtue of the supernatural capacities infused by God.

b. Implication: Rarity of Miracles

What Sts. Augustine and Thomas Aquinas defined as a miracle, however, cannot depend on this regularity and predictability precisely because it is unusual and, in this theological tradition of reflection, does not effect a change in the nature of the creature miraculously moved by God. As supernatural action is largely invisible and therefore not relevant to miracles or the natural sciences, we will not treat it further in this article, though it is important to note the distinction in Catholic theology.

Miracles belong to preternatural action and are thus instances of God moving creatures to act in ways that are beyond their natural capacities. These are unusual instances where God moves creatures in ways to which they are not disposed to move (or able to move alone) for significative and testimonial purposes, as we will cover below.

The rarity of miracles, as mentioned above, is not only a part of their definition, but it also allows miraculous action not to interfere with the normal processes of the natural sciences. A miracle is a miracle in the sense of preternatural action (God’s direct action on the creature). If God instead bestowed a quasi-faculty of supernatural action that had visible effects, such as the ability to shoot fire out of one’s fingers, then a scientific investigation would be able to find the circumstances in which the regular exercise of those effects would happen. There could conceivably be a scientific law or a science of that particular supernatural ability that would certainly interfere with the normal process of the natural sciences by giving a regular and repeatable instance of a creature acting beyond its nature. While it is within the power of God to do this, God tends to only make these empirically detectable actions through unusual and preternatural actions rather than through the continuous operations of supernatural actions. The Lord in His wisdom knows why He determined this to be the case, but there would have been nothing preventing Him from, for instance, making the sacraments glow every time they were performed. As this is not the case, rare preternatural action does not interfere with the process of the contemporary sciences.

c. Praeter Naturam not Contra Naturam

Before we move on to the epistemological questions of how the Catholic Church determines which miracle claims are authentic, we need to address an important objection to miracles. Some theologians argue that God allowing a creature to act in ways normally against the nature of the creature is inconsistent with God’s creative rationality. If God created creatures with certain powers and ordered the universe in a wise and rational way, why would God later interfere with the way creatures exercise their natural powers? Did God not properly plan out His actions and thus have to improvise and make creatures do things He did not plan to make them do? Even if He planned it, isn’t it an offence against the dignity and integrity of creatures to force them to act against their natures?

This objection to the rationality of miracles has some roots in the thought of St. Thomas Aquinas. St. Thomas Aquinas argues that, even though God may cause creatures to act in ways that might be different (and even opposed) to their natural inclinations, God, by the very fact that He is the source of nature, could never do something against the whole course of nature (contra naturam). Rather, He acts beyond nature (praeter naturam).{34}

 At first, this might sound like special pleading, as though St. Thomas is saying that it wouldn’t count if God made creatures act against their natures when any other creature would be acting against nature. However, God’s causality is fundamentally different from creaturely causality. God’s miraculous causality is an extension of His creative causality. God is the creator of all that is and is the source of all creatures’ existence at every moment.{35} Theological traditions of analysis have often called God’s causality “primary causality” and creatures “secondary” or “instrumental causality” because creatures depend on God’s creation and on God sustaining them in their every action.{36} God’s creative sustaining of creatures has traditionally been called “concursus divinus” to highlight the fact that God’s creative act is a “flowing into” creatures that empowers them to act.{37} God’s creative action is first of all non-competitive because God’s causality makes creaturely causality possible and is not the same kind of action as derived, creaturely actions are. Both creatures and God truly act in every action, but creatures act by means of the creative act of God, making them dependent on God’s prior creative action in order for them to act by their own proper natures.

Metaphysically, miracles rely on a feature of creatures called by some traditions of Catholic theology by the name of “obediential potency.”{38} Obediential potency is the openness of a creature to be moved by God in ways its nature is not capable of. The term emerges from medieval reflection on God’s miraculous creation of Eve from Adam in the Genesis narrative. All creatures, because their whole existence and abilities come from God, are able to be moved by God in ways not grounded in their particular nature (i.e., in a preternatural way). This feature of creatures is completely dependent on God’s power and creative activity; there is no specific actuality of the nature of a specific creature that makes it possible to perform this preternatural activity. Being a creature entails being open to God’s creative act (i.e., having obediential potency).

In preternatural, miraculous action, then, God is not forcing creatures to override their natural actions, but God is moving them by something prior: His creative action. Something like obediential potency is necessary even for the human being to be transformed to have grace as a quasi-nature that allows human beings to act supernaturally in grace.{39} While there are great debates about how exactly human nature relates to the supernatural end of the beatific vision, the ability for human beings to be changed by Baptism to become capable of receiving sanctifying grace is due to the continuous ability of God to expand creatures’ ability by a kind of re-creation in them. This is possible because of their obediential potency.

Thus, the reason why miracles are neither irrational for God nor special pleading in God’s case is because preternatural miraculous action takes place in the context of the creative action of God, which is prior to the action of creatures in their specific natures. Because of obediential potency, preternatural miraculous action is always consonant with creatures’ relationship with God. Creatures are always open to God’s further creative action, so being moved to do things not possible through their natures is an action more fundamental to what they are than even their natures. Thus, the possible objections concerning creaturely integrity are dismantled.

Similarly, obediential potency shows that miraculous action is not a mere arbitrary improvisation, but that creatures at all times are ready to be moved beyond their natures. This connection between the fundamental creatureliness of creatures and miraculous action shows that the possibility for miraculous action is present from the very moment of creation and is not a later, arbitrary improvisation. Below, we will cover the other side of this question: that of the rational reasons God has for miracles. Before we conclude the section on the metaphysics of miracles, however, there is one more issue to be raised, flowing from the rootedness of miraculous action in the creative action of God.

d. Creation of Secondary Effects without Secondary Causes

The objection to miracles outlined above also implies another widespread presupposition about the sciences touched upon earlier. We have already mentioned that the laws of science are not inviolable as far as empirical observation is concerned. Many people also assume that the natural world is causally closed to any further action by God. There is the assumption that, even if our individual observations do not conform to the generalized law of science, there is an underlying law of nature that is inviolable and to which our observations have not yet caught up. The assumption is that the laws of nature, and by extension, everything about the physical universe, is closed to divine infusion of additional creative action not covered by the laws of nature.

Given the openness of creatures to God in obediential potency, this presupposition is theologically impossible. Not only can God cause individual creatures to act in ways that exceed their natural capacities, but there is no reason why God would have to limit His creative action to the genesis of the universe. The presumption that the universe will not have more creative action is a philosophical presupposition. While it is good scientific practice to always look for a natural cause, sometimes the scientific approach is frustrated. In these circumstances, philosophical and theological approaches must provide fuller analyses.

From the miraculous virginal conception of Jesus to medically testable Eucharistic miracles of the twenty-first century, Catholics see evidence that God works empirically detectable miracles well beyond initial creation. Moreover, Catholics, by accepting Christian revelation, also accept this possibility. But in addition to elevating creatures above and beyond their natures, there is another, simpler way in which God can work miracles: by producing creaturely effects without creaturely causes.{40}

God is not bound to use the creatures that normally produce certain effects in order to produce these effects Himself. He can create the effect without the cause because He is the creator of the universe. The Lord providing Elijah with baked cakes (1 Kgs 19:6–8) is a good example of God directly producing something normally produced by secondary causes. What God creates is not necessarily preternatural, but the way in which God produces them, without secondary causes, is miraculous. It is not a different kind of creation from God’s creation of the universe. Moreover, the numerous acts of creation that happen every day, including the direct creation by God of every human soul at conception, are another testament that God still continues to create and to produce secondary effects without secondary causes. This is distinct from God’s normal creation and His sustaining and guiding of creaturely causes and their effects.{41}

B. Detecting Miraculous Action

How can we know whether a phenomenon has exceeded the natural capacities of a creature and is thus miraculous? The Catholic Church does not investigate all strange occurrences as possible miracles—only those happening in alleged connection to someone whose heroic virtues have been evident enough to merit the opening of a cause for canonization or those long-standing phenomena claiming direct connection with the Catholic faith.

St. Thomas Aquinas considers this criterion necessary because of the testimonial role that miracles play in confirming the faith and holiness of an individual.{42} Miracles are those acts of God by which God signifies His creative and salvific will. As such, they are a powerful support of divine revelation and are a source of encouragement to sanctity for the faithful.

The thought of St. Thomas Aquinas can help us treat one significant issue with respect to miracles and gesture to another. The first significant issue is the fact that, while only God can work miracles, St. Thomas holds that (following Old Testament precedent), demons can also work superhuman acts which are not miracles. Discerning the difference between demonic action and divine action is of great import to the theologian. St. Thomas speaks of angelic and demonic action as the influence of a superior power on a lower power, in the same way that the moon has an influence on the tides or a squirrel can throw a rock. Both are the influence of natural superior agents which cause the thing acted upon to be actualized in a way that exceeds the power of its nature to actualize alone. The key difference is that there is a passive potency in the nature of the water or the rock that allows it to be moved in such a fashion by a more powerful agent. It is the mass of the water that allows it to be attracted to another massive object such as the moon, and it is the stable structure of the rock that allows it to be picked up and thrown by animals. There are some potentialities in creatures that can only be actualized by higher agents. It takes human intervention to ferment, grind, mix, and bake flour, water, yeast, and sugar to make bread, something the ingredients could not do on their own. Human beings have even actualized the potentialities in atoms to form new chemical elements not found elsewhere in the cosmos.

St. Thomas Aquinas also points out that angels and demons can also influence the physical world in ways that show they are superhuman but still natural agents. Their intellects are sharper and more powerful, as are their influences on the physical world, but their influences are not on the level of actualizing existence. Only God can work miracles by creating a new temporary effect in the creature without an intermediary and through the relationship of existence. Angels and demons, however, can influence the physical potentialities latent in creatures by applying natural forces to local motion or change (i.e., physical changes).{43} Because of the subtlety of these physical changes, and because they are beyond our ability to follow or understand, they may seem miraculous when they are actually only precise applications of natural forces.{44} This can also apply to cases when human beings discover or use new aspects of the physical world such as magnetic levitation of metals or combustion of petroleum on water, causing the water to appear on fire. While the angelic or demonic cause may be hidden, the result is a wonder but not a miracle.

The second issue related to this that we will gesture towards, but not treat substantively, is whether God works miracles outside of the Catholic Church, in Christianity more broadly, or in Judaism. Many of the Fathers of the Church considered all alleged miracles or wonder-claims on behalf of pagan gods to be the work of demons.{45} Some Fathers and Doctors of the Church considered that miracles could happen in support of some clearly virtuous practice of non-revealed religions. For example, St. Augustine and St. Thomas Aquinas apparently told of miracles attesting to the holiness of vestal virgins in pagan Rome.{46}

The possibility of miracles outside of the Catholic faith, the context in which the Catholic Church would affirm a miracle, and the possibility of demonic action make discerning the veracity of miracles a difficult task. In order not to be deceived, miracle claims are evaluated in the context of theological testimony to those things and people that are holy. The Catholic Church’s contemporary procedures are to admit miracle claims in support of a person’s holiness only after diligent investigation among that person’s published and unpublished writings, as well as the eyewitness testimonies to that person’s life.{47} These witnesses must be scrutinized by those responsible for the investigation so that no questions arise as to their veracity, principally with regard to the sanctity of the candidate for canonization. If, at any point in the process, the person’s writings are discovered to be against good faith and morals or if there is an immovable obstacle in the witnesses to establishing the holiness of the candidate, then the cause for canonization ceases. This means there are no investigations of miracles obtained through the candidate’s alleged intercession.{48} In the contemporary canonization process, the testimonial context is of primary importance.

In 2024, the Dicastery for the Doctrine of the Faith promulgated new norms and directions for the discernment of alleged supernatural/praeternatural phenomena.{49} While these norms are largely intended for the pastoral guidance of bishops (e.g., to protect their flocks from fraudulent phenomena or the abuse of authentic spiritual phenomena), some aspects of the process are helpful to reflect on as theologians in discerning the relationship between miracles and the natural sciences.

As is customary, the Catholic Church does not declare particular apparitions or other preternatural phenomena to have certainly come from God’s miraculous intervention. Rather, she issues, where appropriate, a negative judgement that nothing stands in the way of the faithful believing such an event to be miraculous. Post-revelation miracles, even if they pass doctrinal and expert tests, do not become objects of the faith obligatory for Catholics to believe.{50} When a claim to supernatural activity is made, the diocesan bishop must assemble a commission of experts, including a theologian, a canonist, and an expert in the area in which the miracle-claim is alleged (e.g., a hematologist for miracles relating to blood, a cardiologist for those pertaining to the heart, etc.).{51} While the bishop is instructed not to make a public determination about whether a miracle has taken place, the purpose of the commission, whose minutes are sworn to secrecy, is to determine “the truthfulness of the occurrences in question, but also to carry out a detailed examination of every aspect of the event.” This implies that the commission makes a determination regarding whether or not supernatural activity has taken place.{52} Indeed, should the evidence reveal it to be a hallucination, mistake, fraud, or similar conclusion, then the bishop can rule that the phenomenon is not supernatural.{53} In the cases of medical miracles attained through the intercession of saints, a medical council of six or seven experts must give its affirmation that the subject cannot have been healed by natural means. At least two-thirds of the council must agree on this affirmation.{54} The way in which the Church discerns the veracity of a miracle, therefore, is to exhaust the scientific knowledge of experts.

An even more important criterion is the theological context of the miracle. If the alleged miracle is accompanied by a doctrinal claim, then the Church diligently investigates the content of the message for doctrinal orthodoxy as well as the use to which it has been put. She also investigates the holiness of the life of the person.{55} If the person is found to be holy and the message is found to be doctrinally orthodox, then such a claim, according to the judgment of the experts on the commission, is evidence that the Holy Spirit is guiding the people of God to grow more deeply in holiness in a particular way through the saint or phenomenon. The Church then promotes devotion to the saint or place in order to deepen the holiness of the faithful.{56}

The fundamental role of miracles is to bring the faithful closer to God through the sacred mysteries. God’s periodic display of wonders redirects the faithful’s attention to Jesus Christ and the supernatural means He has given us to grow in holiness: the sacraments, acts of charity, and all of the ordinary means of Christian life in the Church. The natural sciences not only do not contradict these extraordinary events of God, but the Catholic Church makes extensive use of experts in the natural sciences to investigate their occurrences. Coupled with a metaphysico-theological analysis, the sciences can help present miracles as powerful motives of credibility and inspirations to faith for both the faithful and the world. Miracles are a visible manifestation of God’s continuing work in the world, pointing to the ongoing invisible transformation of supernatural life God gives in the Catholic Church every day. Through these wonders, God inspires both rational reflection and supernatural faith within the harmony of faith and reason.