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St. Thomas Aquinas and the Fittingness of Evolutionary Creation, Part 1

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December 30, 2013 Tags: Evolution & Christian Faith project, History of Life
St. Thomas Aquinas and the Fittingness of Evolutionary Creation, Part 1

Today's entry was written by Rev. Nicanor Pier Giorgio Austriaco, O.P.. Please note the views expressed here are those of the author, not necessarily of BioLogos. You can read more about what we believe here.

As a priest-scientist who supervises an NIH-funded research laboratory investigating the molecular regulation of cell death, I get a lot of science and religion questions from believers and non-believers alike. The second most common question I get – after the most common truth question, “Do you believe in evolution?” – is the purpose question: “Why did God choose to create via an evolutionary process rather than via special creation?”

Many answers to this purpose question are possible, of course, but I have found that the most illuminating, and often the most surprising, response that I can give is an argument based on the thought of the great medieval and scholastic thinker, St. Thomas Aquinas, who lived in the 13th century. It is a theological argument for the fittingness of evolutionary creation.

St. Thomas was a Christian theologian whose most mature work, called the Summa Theologiae, remains a masterpiece of faith-seeking understanding. In his writings, he frequently used theological arguments for fittingness to reveal the meaning, beauty, and wisdom of God’s actions in the world. Arguing from fittingness involves understanding why an end is attained better and more conveniently with the choice of one particular means rather than another. In this sense, and as St. Thomas himself explains, choosing to ride a horse is more fitting than walking if one seeks to quickly reach one’s destination on a journey (cf. Summa Theologiae, III.1.2). Theologically, arguments from fittingness try to explain how God’s choice of a particular means allowed him to most appropriately attain the end of his actions.

It is important to acknowledge at the outset that theological arguments from fittingness are not demonstrative. In other words, they cannot prove that a certain conclusion necessarily has to be the way that it is. They cannot prove that the conclusion is true. It may be fitting for someone to ride a horse to reach his destination, but he may in fact have chosen to walk instead. Theological arguments from fittingness do not prove doctrine. They attempt to reveal the inner coherence and the wisdom of the divine design, the theo-drama that has been revealed by a God who is true, good, and beautiful. Nonetheless, these arguments have been deployed by Christian theologians throughout the history of the Church to illustrate the coherence, the intelligibility, and the beauty of the Christian faith. For example, the author of the Letter to the Hebrews argues that it was “fitting [επρεπεν] that God, for whom and through whom all things exist, in bringing many children to glory, should make the pioneer of their salvation perfect through suffering” (Heb 2:10; NRSV).

Returning to our topic, we can reword the question as follows: Why is it fitting for God to have created via an evolutionary process rather than via special creation?

To answer this question, recall that for St. Thomas, theological arguments from fittingness attempt to explain how God’s choice of a particular means allowed him to most appropriately attain the end of his actions. Therefore, to grasp my argument for the fittingness of God’s creating via evolution, we need to begin by identifying the end of creation. Why did God create?

The Catholic theological tradition, which is representative of most of the other Christian traditions, has a clear answer to the purpose-of-creation question: God chose to create because he wanted to manifest and to communicate his glory. The Catechism of the Catholic Church, the definitive summary of Catholic doctrine, proclaims that, “Scripture and Tradition never cease to teach and celebrate this fundamental truth: ‘The world was made for the glory of God’”  (no. 293).

How does God communicate his glory to his creatures? According to St. Thomas, God communicates his glory to his creatures by inviting them to participate in his existence. Creatures exist because God, whose essence is existence itself, gives them a share in his existence. This is the fundamental metaphysical distinction that distinguishes the Creator from his creatures: he has existence by nature, while they have existence by participation.

However, St. Thomas also explains that God shares his perfections with his creatures by inviting them to participate in his causality, which in the world manifests itself in his governance of his creation:

But since things which are governed should be brought to perfection by government, this government will be so much the better in the degree the things governed are brought to perfection. Now 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. Therefore God so governs things that He makes some of them to be causes of others in government; as a master, who not only imparts knowledge to his pupils, but gives also the faculty of teaching others. (Summa theologiae, I.103.6)

To put it another way, according to St. Thomas, it is a greater perfection, and therefore, more fitting, for God to share his causality with his creatures, making them authentic causes that can cause by their own natures, than for God to remain the sole cause acting within creation.

As I have explained to my students at Providence College, it is easy for human beings to write a book, but it is impossible for them to make a book that writes itself. On the other hand, God not only causes, but also creates creatures who are in themselves true causes. As such, when God does create creatures who themselves can cause, he manifests his power in a singular manner that signals his omnipotence.

Building upon this Thomistic theological account, I propose that it was fitting for God to have created via evolution rather than via special creation because in doing so, he was able to give his creation – the material universe and the individual creatures within it – a share in his causality to create. In this way, he more fully communicates his perfection to his creation, thus, more clearly manifesting his glory. As St. Thomas points out: “If God governed alone, things would be deprived of the perfection of causality. Wherefore all that is effected by many would not be accomplished by one.” (Summa theologiae, I.103.6)

Note that this is not the causality that allows one to create from nothing, because this causality is the sole prerogative of God who alone is creator. Rather, it is the causality that allows one to create novelty and diversity from pre-existing matter. This is also not the causality that philosophers call primary causality. Again, this is the sole prerogative of God who is able to act solely on his own power. Instead, it is the causality called instrumental causality where God, the primary cause, activates the instrumental causality of his creatures so that he and they can act together wholly and fully, to create, in the same way that an author and his pen work together wholly and fully to write a letter. This is the kind of causality that underlies biological evolution.


Rev. Nicanor Pier Giorgio Austriaco, O.P., currently serves as an Associate Professor of Biology and an Instructor of Theology at Providence College in Providence, Rhode Island. He received his Ph.D. in Biology from M.I.T. and his Pontifical Doctorate in Sacred Theology (S.T.D.) from the University of Fribourg in Switzerland. His NIH-funded laboratory at Providence College is investigating the genetic regulation of programmed cell death using the yeasts, Saccharomyces cerevisiae and Candida albicans, as model organisms (http://www.austriacolab.com). His first book, Biomedicine and Beatitude: An Introduction to Catholic Bioethics, was published by the Catholic University of America Press.

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Roger A. Sawtelle - #83992

December 30th 2013

God, whose essence is existence itself,

God’s essence is Love.

Nicanor Austriaco, OP - #84001

December 31st 2013

Both these statements are not mutually exclusive. To say that God is that being whose essence is His existence, is to try to explain how God is radically different from His creatures whose essence does NOT include existence. To say that God is love is to explain how He relates to Himself and to His creation. Two different ways of describing God from different perspective, where the first is metaphysical and the second is analogous.

Scott Kostencki - #83993

December 30th 2013

Loving this thought process so far…can’t wait to see the next part.

Two presumtions though I would love to see discussed:

1. This approach, as most I suppose, attempts to guess the perspective of God in understanding His choice(s) in creation, when all we can truly do is appreciate and accept it.

2. The starting point as stated, “...we need to begin by identifying the end of creation,” is wide open for guess work, since we are not at the end of His creation and what we have evolved into so far is not what we may yet be.

Loving this brain-candy though! Thank you for it! :-)

Scott K.

2cortenfour - #83995

December 30th 2013

Scott -
When you say “and what we have evolved into so far is not what we may yet be”, I’m just curious if you have in mind 1 John 3:2(b):
“...what we will be has not yet been made known.”?

Nicanor Austriaco, OP - #84002

December 31st 2013

To respond to your two points:

1. This approach assumes that God is not only all-powerful but is also all-wise and all-reasonable. It assumes that when He acts, He acts according to His reasons, which He is able to reveal to us, either through both the Book of the Word and the Book of Creation. We may not be able to discern all His reasons truly, but we can try because by giving us faith, hope, and charity, God has invited us to participate in His very knowing and His very loving. For St. Thomas Aquinas, when we believe with faith, we begin to know what God knows as He knows it, but in a limited, creaturely, manner. When we love in charity, we begin to love as God loves. Which is why we are able to love, with God’s  grace, as Jesus loved.

2. Yes, we can guess, but we can also ask. As Christians, we believe that God revealed His purposes to us in His Word, His Son, the Savior of the world. So what does the Sacred Scriptures—interpreted by the authoritative Christian community that wrote it in the first place—tell us about God’s purposes in creating. For one, since God is love, we can discern that He created us from love and for love. And that is only just the beginning…

Chris Wisehart - #83994

December 30th 2013

Is it possible that the first instance of creation contains an eternity of time that obscures our judgment about time.

Eddie - #83997

December 30th 2013

I thank Dr. Austriaco for his even-toned and expository article.  Among the points I most appreciated was his admission that arguments from “fitness” are not proofs; we cannot insist on the conclusion that God would do such-and-such rather than so-and-so because, in our opinion, such-and-such would be more “fitting” for God than so-and-so.  This is a point not often appreciated by American TEs, who tend to rather casually assert or to strongly imply that evolutionary creation is more theologically appropriate than direct creation.

However, there is a certain problem in Dr. Austriaco’s procedure regarding Thomas Aquinas.  He argues from general principles of Thomistic theology, without taking into account the actual views of Thomas regarding the creation of the world.  Thus, since according Thomas’s principles it would be “fitting” for God to create beings which themselves have creative power, Dr. Austriaco appears to conclude that a good Thomist would support a self-evolving universe, such as that envisioned in modern “molecules to man” thinking.  The difficulty is that Thomas himself, in his detailed account of creation, did not draw this conclusion; he in fact argued that both man and the higher animals were created directly, not produced by the creative powers of earlier created things.  So Thomas himself would appear not to have understood his own principles. 

What should we conclude?  That Thomas did not follow through consistently on his own principles?  Or that Dr. Austriaco (and others) have not properly applied those principles, since they fail to account for Thomas’s view that some things were created directly and not mediately?

Identifying an unjustified inferential leap in Dr. Austriaco’s account which may help resolve this problem.  God allows some of his creatures to have causal powers of their own; but it does not follow that this causal power was understood by Aquinas to be the power of originating a new kind of thing.  The causal power may be simply the power of generating, i.e., perpetuating an existing kind of thing.

E.g., fruit trees have the power to bear fruit, which contains seeds for future fruit trees.  The fruit tree therefore shares in God’s creative, causative power; it contributes to the making of new fruit trees like itself.  It is not necessary, in order for the fruit tree to have this power, that it should have the ability to generate an entirely different species of fruit tree.  It is already causally efficacious, even if its efficacy is limited to reproducing its own kind.  The same is the case in animal gestation.  The mother’s gestational powers help to produce the live offspring; the mother thus contributes, of her own maternal nature, causal efficacy.  It is not necessary, in order for a mother horse to have this causal efficacy, that it should be able to produce a proto-rhinoceros.  In other words, “evolution” as commonly understood is not implied by Aquinas’s principles.  It is not ruled out by them, but certainly not implied. 

This explains why Aquinas could believe that man, and the higher animals, were created directly, rather than evolved from lower beings.  Aquinas did not interpret his own principles as Dr. Austriaco interprets them.  He did not think that it was always “more fitting” for higher beings to be produced only through the mediate causality of lower beings.  He thought that sometimes it was “more fitting” for higher beings to be produced directly.

I sometimes think that Thomist scientists are too eager to harmonize the teachings of Thomas with the teachings of modern science.  It seems to me that the first thing to do is to get straight, not what modern Thomism says, but what Thomas himself taught, and that, when his apparent principles (as deduced by modern Thomists) seem to conflict with his very clear direct statements, his very clear direct statements should have more weight than his apparent principles, since his apparent principles may be not his own principles, but the constructions of modern Thomists bent on making Thomas’s thought seem more modern and more scientific than it may actually be.

Nicanor Austriaco, OP - #84003

December 31st 2013

So much could be said to respond to this excellent post. The questions are important ones, but in this short space, I would just like to address the question of whether St. Thomas ruled out the possibility of creation after the work of special creation had been accomplished. In his masterful Summa theologiae, he will say the following: 

Nothing entirely new was afterwards made by God, but all things subsequently made had in a sense been made before in the work of the six days. Some things, indeed, had a previous experience materially, as the rib from the side of Adam out of which God formed Eve; whilst others existed not only in matter but also in their causes, as those individual creatures that are now generated existed in the first of their kind. Species, also, that are new, if any such appear, existed beforehand in various active powers; so that animals, and perhaps even new species of animals, are produced by putrefaction by the power which the stars and elements received at the beginning. Again, animals of new kinds arise occasionally from the connection of individuals belonging to different species, as the mule is the offspring of an ass and a mare; but even these existed previously in their causes, in the works of the six days. Some also existed beforehand by way of similitude, as the souls now created. And the work of the Incarnation itself was thus foreshadowed, for as we read (Philippians 2:7), The Son of God “was made in the likeness of men.” And again, the glory that is spiritual was anticipated in the angels by way of similitude; and that of the body in the heaven, especially the empyrean. Hence it is written (Ecclesiastes 1:10), “Nothing under the sun is new, for it hath already gone before, in the ages that were before us.” [Summa theologiae I.73.1 ad 3]

Now clearly, St Thomas did not know any of the biology that we know today. Like his contemporaries, he thought that God created the world as Genesis explained it. However, it is striking that he was open to creation after Creation because he observed the appearance of new species from pre-existing ones, i.e., the mule as the offspring of an ass and a mare.

My blog post is not meant to conclude that St. Thomas was himself a theistic evolutionist. However, I do want to show that there are openings in his theological synthesis that can be brought into conversation with contemporary science, especially contemporary biology. As he brought Aristotelian notions into conversation with the currents of his own day, we can do the same with his work in ours.

Eddie - #84014

January 1st 2014

Dr. Austriaco:

Thank you for your gracious reply to my post.  I hope my remarks above did not sound strident or aggressive.  You have clarified your meaning admirably and your response is dialogical rather than defensive.  Thank you also for the Aquinas passage.  I think your contributions will make a great addition to BioLogos.

Jon Garvey - #83998

December 31st 2013


You’re absolutely right that applying Aquinas without addressing his mediaeval worldview adequately is dangerous. He’d have thought long and hard about how creation doctrine could be applied to evolution.

He wrote of spontaneous generation of lower forms, which was then accepted science of course, and the closest he could get to evolution. But it’s clear he saw that as mere generation of already created forms, not as any kind of new creation.

In fact, I agree with your critique in that, for Aquinas, there was not a distinction between ex nihilo creation and other creation - to him, creation was definitionally ex nihilo. That raises the issue of what is ex nihilo within evolution and therefore God’s direct work, and I suspect he’d have largely parcelled that out to formal causation: the design of form, if de novo, must be from God directly, not via any secondary “creation”.

At the same time there are some important and correct caveats in Rev Austriaco’s article which are significant lessons for modern TEs, especially for those many here who seem to be in the thrall of free process theology.

The first is his noting of Thomas’s emphasis on what would be the most fitting means to attain God’s ends in creation. In other words, final causation is primary, and as both the author and Aquinas are clear, the manifestion of his glory in at the heart of that, dictating that the most suitable means must be the wisest and that most tending to good ends. Only that would be good enough to reflect his glory.

The second point he notes is that secondary causation does not replace God’s primary causation. It’s easy to gloss over that if you’re unfamiliar with Aquinas, but it doesn’t mean a Deistic initial creation plus or minus God’s sustaining hand thereafter - it means that God’s efficient causation precedes the secondary efficient causation in every event.

God is therefore responsible for every event - and to construct a theodicy based on the autonomy of secondary causes is utterly alien to his thought.

That links to Austriaco’s third key caveat, which is his use of the phrase “instrumental causality”. This is to be distinguished from the causality of agents - a distinction NOT made by far too many TEs. The difference is like that between a man who uses a power tool or a computer to make something - or even one who gives detailed instructions to a labourer - and the man who asks a skilled artist or engineer to create some masterpiece of his own.

The net result of all this is actually quite a significant shift in the focus of evolutionary creation, as Thomist Etienne Gilson has pointed out. Austriaco’s article actually describes an evolutionary process that is an unfolding (e-volution) of what the Creator God has already instilled into nature’s secondary causes.

Whereas Darwinian evolution (as commonly understood even by many theists) is a less-coherent notion of novelty arising ex nihilo by chance and necessity without God’s ongoing creative input. The latter seems to me, at least, a million miles from Aquinas.

Nicanor Austriaco, OP - #84004

December 31st 2013

Thank you for your insightful reply. I only have to add one comment to expound on your last statement regarding chance and necessity. For St. Thomas, everything created, because it is created, falls under the providence of God. In fact, he will claim—for metaphysical reasons that I cannot get into here right now—that properly understood, chance events are chance events precisely because God made them that way, and necessary events are necessary because God made them necessary. That is why it is metaphysically coherent to say that God guided the evolutionary process via a mechanism that was genuninely contingent. The Catholic Church’s International Theologial Commission explained it this way, citing St. Thomas:

“According to the Catholic understanding of divine causality, true contingency in the created order is not incompatible with a purposeful divine providence. Divine causality and created causality radically differ in kind and not only in degree. Thus, even the outcome of a truly contingent natural process can nonetheless fall within God’s providential plan for creation. According to St. Thomas Aquinas: “The effect of divine providence is not only that things should happen somehow, but that they should happen either by necessity or by contingencyTherefore, whatsoever divine providence ordains to happen infallibly and of necessity happens infallibly and of necessity; and that happens from contingency, which the divine providence conceives to happen from contingency” (Summa theologiae, I, 22,4 ad 1). In the Catholic perspective, neo-Darwinians who adduce random genetic variation and natural selection as evidence that the process of evolution is absolutely unguided are straying beyond what can be demonstrated by science. Divine causality can be active in a process that is both contingent and guided. Any evolutionary mechanism that is contingent can only be contingent because God made it so. An unguided evolutionary process – one that falls outside the bounds of divine providence – simply cannot exist because “the causality of God, Who is the first agent, extends to all being, not only as to constituent principles of species, but also as to the individualizing principles….It necessarily follows that all things, inasmuch as they participate in existence, must likewise be subject to divine providence” (Summa theologiae I, 22, 2).

Source: http://www.vatican.va/roman_curia/congregations/cfaith/cti_documents/rc_con_cfaith_doc_20040723_communion-stewardship_en.html

Jon Garvey - #84012

January 1st 2014

Thank you for your exposition of my last para, with which I entirely agree but would have put far less well as a newcomer to Thomas’s thought. It seems to me that the lesson of the universality of providence is much-needed in a theistic evolution that tends to borrow too much from materialist metaphysics.

JAG’s point below also seems important to me in applying AT thought to evolution. Assuming that JAG understands “soul” in a hylemorphic sense, as the combination of form and matter to make a unique substance, then to me this does seem to suggest the ongoing creative activity of the Logos (Thomas attributes form especially to the 2nd Person of the Trinity, as I recall).

I’m not sure that Aquinas considered that new forms were created after the original 7-day creation. So he’d surely consider either that the bird is inherent in the nature of the theropod, or concede that deep time implies that the week of creation was metaphorical for an ongoing ex-nihilo creation. Or perhaps he’d modify his definition of creation in the light of John Walton!

JAG - #84018

January 1st 2014

To clarify:  I understand Thomas to understand the soul to be the “morph”/form component of hylomorphism, not the combination.  The composite is, as you say, the substance. 

One way around the problem, as you say, is that God would introduce new souls over time in order to get speciation.  But this seems to break with evolution as it is now understood.  Evolution would make tweaks but never lead to speciation.

Your other solution would not just be the bird inherent in the therapod, but ALL species (past, present, future) inherent in the first cell.  I think Henri Bergson does something like this with his “elan vital” (vital force) as a soul-like force in nature driving things towards more complexity.  But this also seems to be at odds with modern evolution because it’s the eval vital, not natural selection and mutation, that is driving biological complexity. 

Roger A. Sawtelle - #84006

December 31st 2013

Bro. Nicanor wrote

Hence it is written (Ecclesiastes 1:10), “Nothing under the sun is new, for it hath already gone before, in the ages that were before us.” [Summa theologiae I.73.1 ad 3]

With all due respect this statement demonstrates the danger of quoting scripture out of context.  The main theme of Ecclesiastes is “Vanity of vanities.  All is vanity.” 1:2 or freely translated “Emptiness of emptiness.  All life is empty of meaning.”

This message is not consistent with the OT (or the Gospel,) and so there is an addendum which corrects the “wisdom” of the Preacher.   

(Eccl 12:13 NIV)  Now all has been heard; here is the conclusion of the matter: Fear God and keep his commandments, for this is the whole duty of man.

The problem with the “wisdom” of Ecclesiastes is that he beleived that there was “nothing new under the sun,” while the Biblical history demonstrates that there are always new things under the sun. 

Life is truly meaningless and empty of purpose if there is nothing new under the sun.  However when humans are born of God and filled with the Spirit they are truly new creations in Jesus Christ.  

History is based on change and newness.  The physical sciences are based on natural laws that do not change.  Traditional philosophy, “wisdom,” has taken its cue from the physical sciences, rather than from history and theology which is based on God’s salvation history. 

Evolution introduced change into science and philosophy.  Neither has understood it properly which is why it is such a problem today. 

Theology which is based on change, but has been corrupted by philosophy should be taking the lead to reconcile the contradictions between change and stability, but has failed to rise to the occasion.        


JAG - #84009

December 31st 2013

Thanks for this very interesting essay and for your continued comments in the posts. 

I’m interested in what you’d say to the challenge that there is an incompatibility between evolution (as it’s currently understood) and Thomas’ metaphysics.  I’m thinking in particular of his commenary on Aristotle’s De Anima.  As I’m understanding him, Thomas thinks that the soul of an organism defines its species, and also that the soul is ontologically prior to the body.  If these points are true, how could one evolve a new species through genetic change?  You could get physical variation between different individuals within a species, but as long as the soul isn’t modified, it’s still the same species.

One could be an evolutionist and think that the soul arises out of the physical body, or that there are no souls, or that the soul is not particular for a particular species, but it’s hard to see how Thomas’ understanding of the soul could be reconciled to modern ideas about how evolution works. 

I realize based on your reply to Eddie that your essay may only be meant to point out how one aspect of Thomas’ theology can be helpful, and that as Thomas rejected some of Aristotle’s ideas, you may be rejecting some of Thomas’.  But to reject his metaphysics (if that’s what you’re doing) is a pretty major change—much bigger than Thomas’ changes from Aristotle. 

Roger A. Sawtelle - #84010

January 1st 2014

Bro. Nicanor, 

Thank you very much for your response.  Because I am unable to continue the thread above I have copied your response here. 

Both these statements are not mutually exclusive. To say that God is that being whose essence is His existence, is to try to explain how God is radically different from His creatures whose essence does NOT include existence. To say that God is love is to explain how He relates to Himself and to His creation. Two different ways of describing God from different perspective, where the first is metaphysical and the second is analogous.

I certainly agree that these two descriptions of God are not mutually exclusive.  God must exist to love and if God loves God must exist. 

Where I think that I disagree with you is that I think that both of these statements are metaphysical, because God is not Simple, but Triune.  GOD IS WHO GOD IS, and Who God Is is Love.

When God revealed God’s eternal Name YHWH to Moses on the mountain God also revealed that YHWH cared about YHWH’s people. 

Augustine wrote that the Holy Spirit, the Third Person of the Trinity, is best understood as Love.  If the Spirit is Love, then Love must be part of the metaphysical essence of God.  

This is my understanding of the Trinity which is the foundational doctrine of Christianity and is why I make a special point of getting it right.  

Kevin Aldrich - #84243

January 19th 2014

Thanks for this fascinating article. I can see how it is “fit” that God would create by making his creatures real causes of new creatures.

I’d love to hear your thoughts on how it is “fit” that the universe (or at least earth) has been a place of tremendous physical suffering for sentient beings long before the appearance of human beings.

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