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Aquinas vs. Kant

A Message by R.C. Sproul

Thomas Aquinas thought that theology and philosophy could work hand in hand to discover and explain the things of God. He was largely unchallenged until the end of the 18th century, when a philosopher named Immanuel Kant published a groundbreaking book titled, The Critique of Pure Reason. In this lesson, Dr. R.C. Sproul helps us understand why the distinctions between Aquinas and Kant matter to us as we defend our faith.

From the series: Defending Your Faith

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Further Study On This Topic

  1. article

    When Pigs Fly

  2. article

    The Origin of the Soul

  3. article

    The Significance of Thomas Aquinas

When Pigs Fly

R.C. Sproul Jr.

We Protestants tend to have something of a love/hate relationship with Thomas Aquinas. On the one hand, as Protestants, at least we who are Reformed, we value theological brilliance. We admire deeply the mind of Thomas, perhaps even dreaming that had he lived in our day, he surely would have been one of us. On the other hand, as Protestants we, well, protest. That is to say, that brilliant mind was likewise noticed and put to use by Rome. Thomas was a brilliant theologian for the Church of Rome. Brilliant we love—Church of Rome, not so much.

We could spend some time arguing about how good or how bad Thomas' theology was. Decades ago in these very pages, the equally brilliant Dr. John Gerstner, at my request, argued that Thomas' theology was essentially Protestant. Perhaps so. I love and admire the man (or rather men, for the same principle applies to our good Dr. Gerstner) for an altogether better reason. It is because we are a proud people that we rejoice in brilliant minds. What truly commends Thomas, however, was not his brilliant mind but his humble heart.

That heart is brought front and center in one legendary story about Thomas during his student days. The story begins with Thomas entering a classroom. The professor is not yet there, but most of the students are. They are all, however, by the window, craning their necks with excitement. Thomas asks what they are looking at so intently. "Thomas, come quickly," the students respond, "there are pigs—FLYING!" Thomas rushes to the window, only to be met by the uproarious laughter of his fellow students. As the laughter dies down, Thomas gently but potently exposes their sin by saying simply, "I would rather believe that pigs could fly than that my friends would lie to me."

We can, if we are imbued with the spirit of the age, mock such a trusting attitude. We can scorn such credulity. We can even baptize our cynicism with supporting biblical texts. "Come on now, Thomas. Don't you know we're to be harmless as doves, but as wise as serpents?" (Matt. 10:16).

Or, we can see it for what it is—an expression of that godly character which made Thomas a great man. We can see it as that which we should be most zealous to emulate in his life.

Another great and brilliant man of God taught me this when I was a young student. I was a sophomore in high school and deeply and profoundly sophomoric. That is, I thought myself wise, and invested time and energy in cultivating that image. I dressed in black. I listened to ponderous lyrics from esoteric rock bands. I wrote morbid poetry about walls and masks and worms. My father gave me in one fell swoop a rebuke and a challenge. He said to me, "Son, the cheapest way to develop the reputation as an intellectual is to adopt the posture of a cynic."

What I want is not a reputation as either an intellectual or a cynic. What I want is a reputation for following our Lord Jesus. What I want is a simplicity that cares not a whit about reputation at all. What I want is a guilelessness in my own heart that is so grounded that I expect nothing but guilelessness in my fellow believers. What I want is not to be known as a great theologian and a great man of God, but to be known by God as a humble child of His. All of which means, in short, that what I want is to seek first the kingdom of God, and His righteousness.

In the end, our battles for reputation are battles to build and to expand our own kingdoms. We want to be the smartest guy in the room. Then we want to be the smartest guy in the church. Then we want to be the smartest guy we know. We want to be king of Smart-avia. Even if we don't worry about what we will eat, or what we will wear, as those to whom Jesus spoke did, we do worry about what people will think, or worse—that they won't think of us at all.

The world tells us this is how our life will have meaning. This is how we can have significance. The world tells us that pigs are ever and always earthbound. But Jesus calls us to believe Him. He tells us that if we will seek first His kingdom and His righteousness, then we will receive all we could ever want or need. He tells us that if we will delight ourselves in Him, He will give us the desires of our heart. The question isn't whether we are smart enough to understand what He has said. The question is whether we are humble enough to submit to what He has said.

I suspect that when Thomas went on to his reward, he did not cast before the Lord that crown that was his reputation for theological and apologetic brilliance. I suspect that he threw that out long before He got there. Instead the crown he cast before that glassy sea was something valuable, the glory of his humility.

The Origin of the Soul

R.C. Sproul

Students of philosophy are well aware of the watershed significance of Immanuel Kant's epochal work, The Critique of Pure Reason. In this volume Kant gave a comprehensive critique of the traditional arguments for the existence of God, wrecking havoc on natural theology and classical apologetics. Kant ended in agnosticism with respect to God, arguing that God cannot be known either by rational deduction or by empirical investigation. He assigned God to the "noumenal world," a realm impenetrable by reason or by sense perception.

The impact on apologetics and metaphysical speculation of Kant's work has been keenly felt. What is often overlooked, however, even among philosophers, is the profound impact Kant's critique had on our understanding of the soul.

Kant placed three concepts or entities in his noumenal realm, a realm above and beyond the phenomenal realm. The triad includes God, the self, and the thing-in-itself, or essences. If God resides in this extraphenomenal realm, then, the argument goes, we cannot know anything about Him. Our knowledge, indeed all true science, is restricted to the phenomenal realm, the world perceived by the senses. Kant argued that we cannot move to the noumenal realm by reasoning from the phenomenal realm (a point that put Kant on a collision course with the apostle Paul).

Kant's agnosticism moved beyond theology to metaphysics. Since meta-physics is concerned with that which is above and beyond the physical, it is deemed a fool's errand to seek knowledge of essences. The phenomenal realm is the world of existence, not of metaphysical essences or "things-in-themselves." There may be metaphysical essences but they cannot be known by human reason. That Kant did a hatchet job on metaphysics as well as theology is clear.

Again, what is often overlooked is that the hatchet had more work to do. By assigning the self to the noumenal realm, Kant also hacked away at the concept of the human soul. This has had a devastating impact on subsequent views of anthropology. Pre-Kantian thought gave heavy weight to the importance of the human soul. Post-Kantian thought has as all but eliminated the soul from serious consideration.

The nature of the self remains a concern of psychology, but its nature is enmeshed in enigma. Descartes arrived at a knowledge of the self as a clear and distinct idea via a rigorous doubting process. He resolved to doubt everything he could possibly doubt. The one thing he couldn't doubt was that he was doubting. There was no doubt about that. For anyone to doubt that he is doubting, he must doubt to do it. Since doubting is a form of thinking and thought requires a thinker, Descartes arrived at his famous conclusion: Cogito ergo sum, "I think, therefore I am." We notice that in this formula there is an "I," a self, that is necessarily involved in the process.

Kant, himself, could not rid himself of the awareness of his self. He appealed, however, not to a rational deduction by which he came to a conclusion of his self; rather, he coined the idea of the "transcendental apperception of the ego." This technical language is somewhat cumbersome but nevertheless significant. Kant saw the self not as something perceived by the senses. It is an apperception and a necessary apperception for all thought. It transcends the normal process of knowing according to Kant.

What is crucial is that some notion of the self beyond the physical is inescapable. We may argue about how we know we are selves but we cannot deny that we are selves. Descartes was correct: It takes a self to deny the self.

That the human self involves more than the body is clear to all except the most rigorous material determinists who reduce all reality to the purely physical, including thought as mind itself. They reject the Gerstnerian formula: "What is mind? No matter. What is matter? Never mind."

Classical Christian anthropology views man as a substantial dichotomy. This concept is likewise under attack in evangelical circles, not only from the side of trichotomists but also from those who see in it an unwarranted intrusion of Greek philosophy into Jewish-Christian thought. It is rejected by Murray Harris, for one, and was attacked by Philip Hughes, to mention another evangelical scholar.

In my judgment, the rejection of substantial dichotomy rests upon a fundamental error of understanding, a fatal false assumption. Harris and others attack substantial dichotomy because they hear in it a recapitulation of Greek dualism. The Greeks viewed man as a creature locked in a conflict between two opposing and irreconcilable substances, the body and the soul. To the Greek the soul is eternal and good, the body is temporal and intrinsically imperfect. For Plato the nonmaterial ideal realm is the realm of the good. The physical is at best an imperfect receptacle or copy of the ideal. Hence the view emerged in Greek philosophy that the body is the prison house of the soul. Redemption means the release of the soul from the body.

Pythagoras was the source of Plato's theory of the transmigration of the soul, an early version of reincarnation. The soul is eternal but may become entrapped in a series of incarnations during its eternal migration. Redemption occurs when the chain or series of incarnations end and the soul is free to live a bodiless existence.

Herein is the dualism so repugnant to Christian thought. But the problem with the Greek view is not that it has two distinct substances, body and soul, but that it views them as in total conflict with each other, because the physical is inherently evil (at least in the metaphysical sense of evil).

Jewish-Christian thought, however, sees man as made up of two distinct substances that are not in conflict. Nor does the Bible view matter as being inherently evil. For the Christian, redemption is of the body, not from the body. The Christian doctrine of substantial dichotomy is not dualistic. Man is not a dualism but a duality. That is, we have a real body (material substance) and a real soul (immaterial substance). There is an analogy with the person of Christ in that He has two natures or substances, divine and human, united in one person. That He has two substances does not necessitate a dualism in His person. (Of course the human nature of Christ also includes a human body and a human soul.)

That we are made up of body and soul is indicated in the creation account:

"And the Lord God formed man from the dust of the ground, and breathed into his nostrils the breath of life, and man became a living soul" (Genesis 2:7).

In the creation imagery man's body is formed first. But the body without the soul remains lifeless. When God breathes the breath of life into the body, then man becomes a living soul. In this account there is no hint of an eternal or preexistent human soul. The soul is as much a creation as is the body. That the soul survives the grave is not a testimony to its indestructibility or of its intrinsic immortality. The soul as a created entity is mortal. It survives the grave only because it is sustained and preserved by the power of God. It is preserved for eternal felicity for the redeemed; it is preserved for eternal punishment for the damned.

The soul of man can live without the body; the body cannot live without the soul. Jesus exhorted His hearers: "Do not be afraid of those who kill the body but cannot kill the soul. Rather, be afraid of the one who can destroy both the soul and the body in hell" (Matthew 10:28).

From biblical revelation we know we have souls. The Bible does not banish the soul to some "never-never" noumenal world of agnosticism. Not only do we have souls, but the nurture and care of our souls is a top priority for the Christian life.

The Significance of Thomas Aquinas

Ryan Reeves

Thomas Aquinas has always been a whipping boy for theologians. In his own lifetime, his classmates referred to him as the "Dumb Ox" (a play on both his oafish size and the way his critical thinking appeared slow and pondering). The scorn continued after his death, when theologians such as William of Ockham and Duns Scotus attempted to have Thomas' works condemned. Martin Luther, too, found need to reject Thomas' approach to theology. Aquinas had, according to Luther, relied too heavily on Aristotle in his theology, and so Luther warned his readers that philosophical terms from pagan sources could only be used in theology once we have "given them a bath."

A proper historical perspective should allow us to lay down our arms against Aquinas. Protestant theologians may never be fully comfortable with Aquinas' teachings on natural law or reason—and they may have sharper words for his teachings on celibacy, Mary, and purgatory—but he nevertheless stood at the headwaters of a theological resurgence in medieval thinking that would, in time, play a vital role in shaping the landscape of Protestantism.

Thomas was a nobleman born to the Duke of Aquino in Roccasecca, Italy, in 1225. Aquinas, in fact, was not his surname but the home of his family estates, and so his teachings have always been called Thomism and not Aquinism. As a young man, Thomas would have been well educated but spoiled rotten. Thomas himself was the second cousin of Holy Roman Emperor Frederick II, the highest political ruler of the day and a man who was enthroned King of Germany, Italy, and Jerusalem. Such power corrupts, and these were dark days politically. Indeed, for much of the thirteenth century, emperors such as Frederick were not loyal sons of the church. Over time, they began to leverage their own estates, as well as the power derived from the lands won during the Crusades, to begin putting pressure on the pope to do their bidding.

In his first significant act as an adult, Thomas sided against his family's struggles with the church. His father attempted to place his son as abbot of the wealthy monastery at Monte Cassino, not out of piety but in order to prop his son up in a lifestyle fit for his lineage. Thomas rejected this and, we are told, marched into his father's room one day to announce he had joined the begging order of the Dominicans. His family was livid, and his brothers even kidnapped him and imprisoned him in their family castle in the hopes of teaching him some sense. Each of their attempts failed. (One story has them sending a prostitute to their brother, assuming that a life of inflamed debauchery was preferable to a life of service to the church.) Thomas eventually escaped and soon found his way to Paris in order to study with the reigning theologian of Europe, Albert the Great. He would spend the next thirty years studying Scripture and teaching theology.

The two great masterpieces of Thomas' career were his Summa Theologica and Summa contra Gentiles. Both are among the most influential works in Western literature. The Summa contra Gentiles capitalized on the resurgence of Jewish and Muslim literature in the medieval period. Aquinas engages here in an apologetic with unbelievers by providing arguments for the existence of God and for the rational foundation of the Christian faith over against other worldviews.

Even more valuable for later church history was the Summa Theologica, a work that is unrivaled in its scope, covering a staggering number of subjects from questions of sex, the existence of angels, and the function of civil government to traditional doctrines such as Christ, salvation, and the church. In each of his works, Thomas is keen to establish a sure intellectual foundation for the justification of belief (epistemology). It was his exploration of rational argumentation, in fact, that led him ultimately to embrace a modified Aristotelian approach to reason and metaphysics. He struggled long and hard to come up with a solution to the ancient problem of explaining the diversity of life with the unity of ideas—the Problem of the One and the Many. Like Aristotle, Thomas took the view that the unifying reality of particular things stems from God's creation and is implanted in the thing (res) itself, rather than existing outside of the created order.

Thomas' epistemology can be said to hold in tension the biblical doctrines of creation and salvation. He believed that humans are created in the image of God (imago Dei) and therefore have within them the capacity for true and rational thinking. The fall, of course, has obscured this thinking and it leads us to error and sin, but the indelible image of our Creator has not, according to Aquinas, fallen out of our minds. Yet, as Thomas also taught, salvation comes by grace, through Christ, to this same sinful humanity. The doctrine of salvation teaches us that we are not perfect and that our sin can easily obscure the truth. Thomas thus lands on a proposed solution to the problem that he believes will hold both of these truths together: grace perfects nature; it does not destroy it. In other words, though our minds are fallen, they are not destroyed; also, though our natural minds are sinful, yet they receive grace to grasp the truth. This solution was ingenious in that it drew philosophy and science together rather than forcing them apart.

Other areas of Thomas' teachings are problematic. Take, for example, his discussion of sex. Thomas applies his paradigm of "grace perfecting nature" to the question of whether unnatural sins such as sodomy, masturbation, and fornication—indeed any sexual sins outside of marriage—are the greatest sins a person can commit. Thomas contends that these sins are an utter violation of the natural human process of procreation, and therefore constitute a violation of the natural created order as well as a rejection of the grace of Christ that blesses and restores the marriage covenant. Thus, Thomas argues, these sins are indeed among the worst sins possible. Not a few theologians have noted that Aquinas, along with other medieval scholars, ignored biblical teaching on the intimacy and pleasure of the marriage bed, and thereby paved the way for future Roman Catholic theologians to stress procreation as the essence of sex in marriage. It also, and more problematically, suggests an unbiblical gradation of sin by attempting to distinguish between "mortal" (serious) and "venial" (unintentional or small) sins. How can it be said, for example, that sexual sins are more sinful than sins of violence and rage? Why must sexual sins be considered the worst violation of God's law when the fundamental root of all sin is self-sufficient pride?

Further problems are evident in Thomas' teaching on justification. On this subject Aquinas stands tall among medieval theologians, though he later came under serious fire by Protestant theologians. Like many medieval theologians, Thomas taught that Christians receive an infusion of grace at baptism that remains within the soul, though it does not take over the will and force it to do good works. Aquinas holds to a doctrine of predestination, since God chooses by His own will who will receive the infusion of grace through baptism. Still, Thomas refused to conclude that good works are motivated by the Holy Spirit acting upon the will to inspire us to obedience. For Thomas, if love is to be authentic, it must be our own works of love in cooperation with grace. The ethical goal of the Christian life, then, is to actualize this infused grace through good works, which guide us in life unto salvation. These works of love are required of believers in order to receive eternal life, though Aquinas believes he avoids Pelagianism by stressing that the first step in the salvation process is God's gift of grace apart from works.

The most fitting analogy of Aquinas' teachings on salvation is that of exercise. We are all humans, but some of us are flabby and some of us are fit. We have all received our essence from God, since we are all rational beings created in His image. But in order to become more than flabby couch-dwellers, we must exercise our will through the effort of physical labor. No one can lift our arms and legs for us during exercise; the labor is our own. So, too, Thomas believed salvation was a matter of God infusing in the soul the grace sufficient to exercise in works of love, which then lead to eternal life. Our will must grasp this grace and exercise what Thomas called the "habits of grace" in order to grow in love towards Christ-likeness.

Thomas's teachings on epistemology, justification, and ethics are among the most interesting and important subjects that continue to draw theologians to his many writings. Indeed, though Protestants have rejected not a few of his teachings since the Reformation, we can nevertheless look back—as did John Calvin, Philip Melanchthon, Martin Bucer, and even Luther in his quieter moments—and respect the heroic efforts of a theologian who has shaped our thinking for nearly eight hundred years.

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