Chapter 2

Models of Human Nature — A Survey from Physicalism to Substance Dualism

I. Introduction: Why We Need a Map

Before we can see why physicalism creates such devastating problems for the Incarnation, we need to understand what physicalism actually is. And before we can appreciate why substance dualism provides the only adequate foundation for orthodox Christology, we need to see what the alternatives look like and why they fall short. This chapter is our map.

Think of it this way. Suppose someone tells you that a certain bridge is unsafe. Before you can evaluate that claim, you need to know something about bridges — how they are built, what holds them up, and what kinds of failures they can suffer. In the same way, before we can evaluate whether physicalism can support the weight of the Incarnation, we need to understand what physicalism claims about human nature and how it differs from the alternatives.

The question at the center of this chapter is both ancient and urgent: What is a human being? Are we purely physical organisms — nothing more than extraordinarily complex arrangements of matter? Or are we composed of two fundamentally different kinds of reality — a material body and an immaterial soul? The answer to this question matters enormously for theology, and especially for Christology. If we get human nature wrong, we will inevitably get Christ's human nature wrong. And getting Christ's human nature wrong is not an abstract mistake. It touches the heart of who Jesus is, what happened at the cross, and whether the Incarnation survived Good Friday.

I want to be fair to every position we examine. I believe substance dualism is correct, and I will make that clear as we go. But I also believe that truth is best served when we present opposing views honestly and charitably, understanding why thoughtful people hold them. So for each model of human nature, we will look at what it claims, why its defenders find it attractive, and what it means for life after death and for Christology. Only then will we be in a position to see why some of these models cannot bear the weight that orthodox Christian theology places on them.

In laying out this survey, I am drawing heavily on the organizational framework provided by Joshua Farris in his excellent An Introduction to Theological Anthropology, where he maps the major positions in contemporary Christian anthropology and notes their theological implications.¹ I am also engaging throughout with Michael Wilkinson's important argument in Crowned with Glory and Honor that our understanding of human nature should be shaped by Christology — not the other way around.² We will return to Wilkinson's methodological principle at the end of this chapter, but it is worth stating it upfront: we should not first decide what a human being is on purely philosophical or scientific grounds and then apply that conclusion to Christ. Instead, we should look at what Christ's human nature is — as defined by the ecumenical councils — and let that inform our anthropology. Christology norms anthropology, not the other way around.

One more note before we begin. Throughout this chapter, I will refer to the author's companion books where they cover related material. My earlier work Beyond the Grave (Chapters 5–8) presents the biblical and philosophical case for substance dualism, the evidence from near-death experiences, and the dualism-physicalism debate within the conditional immortality movement. This book significantly expands that argument by showing that physicalism fails not only for human nature in general but catastrophically for Christ's human nature in particular. Where relevant, I will note the connections, but this chapter is self-contained — you do not need to have read those earlier works to follow the argument here.

Let us begin our survey.

II. The Landscape of the Debate

As Wilkinson helpfully observes, despite all the disagreements in this area, most scholars working in Christian anthropology agree on a few basic points. Most acknowledge that human beings are embodied beings — we are not ghosts trapped in machines. Most also recognize that human beings have a genuine and important mental or inner life — consciousness, personal identity, moral awareness — that cannot simply be dismissed as an illusion. Most agree that our understanding of humanity should be informed by engagement with the natural sciences. And most agree that any adequate Christian account of human nature must be able to explain how personal identity is maintained through death and resurrection.³

These four areas of agreement are extremely helpful because they set the boundaries of the discussion. They rule out extreme positions on both ends. On the one side, they rule out a purely spiritual view of humanity that denies the importance of the body — the kind of view found in certain strands of ancient Gnosticism, which treated the body as a prison to be escaped. On the other side, they rule out a strictly reductive physicalism that denies the reality of the mind or inner life altogether — the kind of view that says consciousness is nothing but an illusion produced by neurons firing.⁴

Within these boundaries, as Wilkinson notes, the debate comes down to a fundamental question about the number and kind of substances that make up a human being.⁵ Is a human being made of one kind of substance (the physical) or two kinds of substances (the physical and the immaterial)? This is where physicalism and dualism part ways. Both sides use the same basic categories — body and mind (or soul). They disagree about whether the mind or soul is a distinct substance that exists in its own right or merely a function or property of the physical body.

As Farris maps it, the major positions can be arranged on a spectrum. At one end sits reductive physicalism, which identifies the mind entirely with the brain. At the other end sits substance dualism, which holds that body and soul are two distinct substances. In between lie several "middle" positions — nonreductive physicalism, the constitution view, emergentism, emergent dualism, and hylomorphism — each trying to account for the reality of mental life while minimizing or eliminating the need for an immaterial soul.⁶

Let us walk through each position in turn.

III. Reductive Physicalism (Identity Theory)

Reductive physicalism is the most straightforward and uncompromising form of physicalism. It holds that mental states — thoughts, feelings, beliefs, desires, experiences — are identical to brain states. When you feel pain, that pain just is a particular pattern of neurons firing in your brain. There is nothing more to it. When you think about your mother, that thought just is a specific configuration of electrical and chemical activity in your nervous system. There is no soul, no immaterial mind, no "ghost in the machine." You — the whole you, everything that makes you you — are a physical organism. Period.

This view is sometimes called the "identity theory" because it identifies mental states with physical states. The key figures who developed it in the twentieth century include J.J.C. Smart and U.T. Place, who argued in the late 1950s and 1960s that sensations are identical to brain processes, just as lightning is identical to an electrical discharge in the atmosphere.⁷ We do not say that lightning causes an electrical discharge or is accompanied by one. Lightning simply is an electrical discharge. In the same way, the identity theorist says, pain simply is C-fiber stimulation in the brain. There is one event, not two.

The philosophical motivation for this view is straightforward: it is the simplest and most parsimonious explanation. If we can explain everything about human behavior and experience in terms of physical brain processes, why posit anything extra? Occam's razor — the principle that we should not multiply entities beyond necessity — seems to favor this view. It also aligns naturally with a certain picture of science, in which everything in the universe is ultimately explainable in terms of physics and chemistry.

I should note right away that very few Christian thinkers hold reductive physicalism in this strict form. The reason is obvious: if you are nothing but your physical brain and body, then when your body dies, you cease to exist. There is no survival after death unless God intervenes to re-create you from scratch. And even then, as we will see in Chapter 24, the re-created person faces a devastating personal identity problem: is the re-created person really you, or merely a copy?

There is another reason why reductive physicalism has few Christian defenders. It eliminates genuine mental causation. If your thoughts, beliefs, and desires are nothing but brain states — electrical impulses and chemical reactions — then they have no independent causal power. Your "decision" to pray is not really a decision at all. It is just neurons firing in a particular pattern, caused by prior neural events, caused by still earlier neural events, all the way back to the Big Bang. Free will becomes an illusion. Moral responsibility becomes incoherent. And the language of spiritual life — repentance, faith, love, worship — becomes mere metaphor for physical processes that could, in principle, be fully described without any reference to meaning, intention, or purpose.

This is why Farris classifies reductive physicalism as a view that "seems to amount to the elimination of persons as psychological beings that experience value and life as real entities."³⁹ If your thoughts are just brain states, and brain states are just physical events, then in what sense are you — the thinking, feeling, choosing person — real at all? Reductive physicalism threatens not just the soul but the very concept of personhood.

IV. Nonreductive Physicalism

Nonreductive physicalism is the most popular form of physicalism among Christian philosophers and theologians today. Its two most prominent Christian advocates are the philosopher Nancey Murphy, in her influential work Bodies and Souls, or Spirited Bodies?, and the New Testament scholar Joel Green, in Body, Soul, and Human Life.⁸

What sets nonreductive physicalism apart from the reductive version? Like all physicalists, nonreductive physicalists deny that there is an immaterial soul. They hold that a human being is entirely physical — all the way down. But unlike reductive physicalists, they insist that mental properties are real and important and cannot simply be reduced to physics and chemistry. Your thoughts, feelings, and experiences are genuine features of reality, not illusions. They just are not produced by an immaterial soul. They are produced by the physical brain — but they are "higher-level" properties of the brain that cannot be fully captured in the language of neurons and neurotransmitters.

As Farris explains, nonreductive physicalism holds that while the world is made up of physical parts and physics provides some explanation for what happens, physics does not explain everything. Human persons are not reducible to their component physical parts. They are psychological beings that possess properties — consciousness, intentionality, moral awareness — that are not reducible to the physical parts, even though they are composed of those physical parts and arise from them.⁹

Murphy's version is especially worth understanding because she has worked hard to make physicalism seem compatible with Christian faith. She argues for both "bottom-up" and "top-down" causation. This means that higher-level mental properties are not merely passive byproducts of brain activity; they can actually influence the lower-level physical processes. Your decision to pray, for example, is a higher-level mental event that causes real changes in your brain and body. Murphy wants to affirm the genuine reality and causal power of the mental life without positing an immaterial substance to house it.¹⁰

However, as the contributors to Christian Physicalism? point out, Murphy's position faces a serious tension. She clearly rejects ontological dualism — for her, there is no immaterial soul-substance. Yet she also rejects strict reductionism. The question is whether her middle ground is coherent. If there is nothing ontologically beyond the physical, then in what sense are mental properties genuinely "real" and causally powerful? Several critics, including R. Keith Loftin and Joshua Farris, have argued that Murphy's nonreductive physicalism ultimately collapses into either a disguised property dualism (which admits something irreducibly nonphysical) or a disguised reductive physicalism (which eliminates genuine mental causation).¹¹

Joel Green comes at the issue from a different angle — biblical studies rather than philosophy. Green argues that the biblical writers, both Old Testament and New Testament, did not hold a body-soul dualism. Instead, they viewed human beings as unified, psychophysical wholes. The Hebrew word nephesh (נֶפֶשׁ), often translated "soul," actually means "person" or "living being," not an immaterial substance. Greek terms like psychē (ψυχή) in the New Testament, Green argues, should be read the same way. On this reading, the Bible teaches a holistic, monistic anthropology — not the dualism that later Greek philosophy imposed on it.¹²

I find Green's biblical argument unpersuasive, and I will explain why in detail in Chapter 3 when we examine the biblical evidence for substance dualism. For now, I simply note that John Cooper has thoroughly refuted the claim that biblical anthropology is monistic. As Cooper demonstrates, the Old Testament teaches "functional holism" — body and soul are deeply integrated in life — but this functional holism is fully compatible with an "ontological dualism" in which the soul is a distinct reality that can survive the body's death. Holism and dualism are not opposites.¹³

This is a point worth pausing on because it is so often misunderstood. When physicalists like Green argue that the Bible teaches "holism" about human nature, they are correct — but they draw the wrong conclusion from it. Yes, the Bible presents human beings as unified wholes. Yes, the Bible values the body. Yes, the Bible expects a bodily resurrection, not a permanent disembodied existence. All of this is true, and all of it is fully compatible with substance dualism. Cooper calls his position "holistic dualism" precisely because it affirms both of these truths at once: we are unified beings (holism) composed of two distinct substances (dualism). The mistake is to assume that "holism" and "dualism" are contradictory. They are not. A married couple is a unified whole and yet composed of two distinct persons. A duet is a unified musical performance produced by two distinct musicians. Unity does not require identity.

There is another problem with nonreductive physicalism that deserves mention. Several contributors to Christian Physicalism? have pointed out that if Murphy's view is correct — if human beings are entirely physical with no immaterial soul — then this has implications not just for anthropology but for our understanding of God's action in the world. On Murphy's view, God can only influence our mental states by influencing the physical properties of our brains. There is no direct soul-to-Spirit communication. Prayer, illumination, conviction of sin, the internal witness of the Holy Spirit — all of these must be mediated entirely through physical brain states. This is a significant theological cost that many Christians would find unacceptable.⁴⁰

What are the implications of nonreductive physicalism for survival after death? They are the same as for reductive physicalism: without divine intervention, death is the end. There is no immaterial soul to survive. Murphy acknowledges this and argues that God preserves the person through death by a special act of re-creation or reconstitution at the resurrection.¹⁴ But this raises the same personal identity problem that haunts reductive physicalism: if you ceased to exist at death and were re-created at the resurrection, are you really the same person, or a replica?

V. The Constitution View

The constitution view, developed most fully by the philosophers Kevin Corcoran and Lynn Rudder Baker, tries to carve out a middle path within physicalism.¹⁵ It holds that a person is constituted by a body but is not identical to the body. The relationship is like the one between a statue and its clay. A bronze statue of Abraham Lincoln is constituted by a lump of bronze. The statue and the lump are not identical — they have different properties (the lump can survive being melted down and reshaped; the statue cannot). Yet the statue is not made of anything other than the bronze. There is no extra ingredient beyond the physical material.

Applied to human beings, the constitution view says this: you are constituted by your body, but you are not identical to your body. What makes you a person is not your physical stuff alone but the way that stuff is organized — specifically, Baker argues, your capacity for a first-person perspective. You have the ability to think about yourself as yourself, to say "I" and mean it. This first-person perspective is what constitutes you as a person, and it is constituted by your body without being identical to it.¹⁶

As Farris notes, the constitution view is similar to nonreductive physicalism in that it maintains human beings are not reducible to their component parts. It goes further, though, by using the specific constitution relation to distinguish persons from their bodies.¹⁷ The strength of this view is that it preserves a real distinction between person and body — something reductive physicalism cannot do. Corcoran can say, "I am not my body," while still insisting there is no immaterial soul.

But the constitution view has a critical weakness: the constitution relation depends on the body. If the constituting body ceases to function — as it does at death — then the person who was constituted by that body also ceases to exist. Corcoran knows this, and he has tried to address it by arguing that God can "immanently cause" a new body to come into existence that is the same body as the one that died.¹⁸ But this proposal has been widely criticized. Critics have asked: In what sense is a brand-new body the "same" body as the one that decomposed in the grave? And if the person ceased to exist at death, in what sense is the resurrected person the same person?

To see why this is such a serious problem, think of it this way. Imagine that a sculptor creates a beautiful clay statue. The statue is constituted by the clay but is not identical to it. Now imagine that someone smashes the statue to dust. The statue no longer exists — it has been destroyed. Later, someone gathers new clay (or even the original dust) and shapes a statue that looks exactly like the first one. Is it the same statue? Intuitively, the answer is no. It is a perfect replica, but the original statue was destroyed. A new one has been made. The same logic applies to persons on the constitution view. If the constituting body is destroyed at death and a new body is created at the resurrection, we have a replica of the original person, not the original person themselves.

Jonathan Loose, writing in Christian Physicalism?, has argued at length that the constitution view faces a fatal problem with the resurrection. If constitution is what makes a person exist, and the constituting body is destroyed at death, then the person no longer exists. Re-creating a body later does not bring the same person back; it creates a new person who is constituted by a new body. The original person — the one who lived, loved, sinned, and was redeemed — is gone.¹⁹

Baker has attempted to respond to this objection by developing a concept of "derivative" and "nonderivative" properties that persons possess. On her view, persons have certain properties nonderivatively — most importantly, the first-person perspective — that distinguish them from the bodies that constitute them. But critics have countered that even the first-person perspective, on a purely physicalist ontology, must ultimately be grounded in and produced by the physical body. If the body is destroyed, the first-person perspective it generated ceases to exist. Baker cannot have it both ways: she cannot deny the soul and simultaneously claim that the person has properties that somehow transcend the body's destruction.

VI. Emergentism

Emergentism holds that consciousness and mental properties emerge from complex physical organization. When physical matter is arranged in a sufficiently complex way — as it is in the human brain — something genuinely new appears: consciousness, thought, feeling. These emergent properties are real and important, but they remain entirely dependent on the physical system that produces them. If the physical system is destroyed, the emergent properties disappear.

The philosopher Philip Clayton has developed the most significant version of this view in dialogue with Christian theology. Clayton argues that the universe is organized in a hierarchy of levels — physical, chemical, biological, psychological, social — and that at each higher level, genuinely new properties emerge that cannot be fully explained by the properties of the lower levels alone.²⁰ Consciousness is one such emergent property. It arises from the brain's extraordinary complexity, but it is not reducible to individual neurons or their interactions.

Think of it this way. Water has the property of being wet. But individual hydrogen and oxygen atoms are not wet. Wetness emerges when you combine hydrogen and oxygen atoms in the right way and in sufficient quantity. In a similar fashion, Clayton argues, consciousness emerges when neurons are organized in the right way and in sufficient quantity. Consciousness is a genuinely new property of the whole system — not found in any of the parts taken individually — but it remains a property of the physical system. It does not become a separate thing.

The crucial difference between emergentism and the next position we will examine — emergent dualism — is this: in emergentism, the emergent properties never become a separate substance. Consciousness emerges from the brain and depends entirely on the brain. It is a property of the physical system, not a distinct thing in its own right. Pull the plug on the brain, and consciousness vanishes.

One significant philosophical difficulty with emergentism, which several critics have noted, concerns the causal power of emergent properties. If consciousness is merely an emergent property of a physical system, does it have genuine causal power? Can your conscious decision to raise your hand actually cause your hand to rise? Or is the real causal work being done entirely at the physical level — neurons firing, muscles contracting — with consciousness riding along as a passive epiphenomenon, like the steam above a locomotive that has no power to drive the engine? This is the problem of "causal exclusion," developed rigorously by philosopher Jaegwon Kim. Kim has argued that if mental properties are not identical to physical properties, and if the physical world is causally closed (every physical event has a sufficient physical cause), then mental properties are causally redundant — they do nothing.⁴⁵ Clayton's emergentism tries to avoid this by positing "top-down" causation, but whether it succeeds in doing so without smuggling in a form of dualism remains hotly debated.

For survival after death, emergentism faces the same difficulties as other physicalist views. Since mental properties depend entirely on the physical substrate, destroying the brain destroys the mind. There is no soul or consciousness to survive the body's death. Once again, the only hope for afterlife would be divine re-creation — with all its attendant personal identity problems.

VII. Emergent Dualism

Now we come to a position that occupies a genuinely distinctive middle ground. Emergent dualism, developed most fully by the philosopher William Hasker in his important book The Emergent Self, agrees with emergentism that the soul emerges from the brain's complexity. But it makes a crucial further claim: once the soul emerges, it becomes a distinct immaterial substance in its own right.²¹

Think of it like this. On ordinary emergentism, consciousness is like a flame produced by a candle. The flame depends entirely on the candle; extinguish the candle and the flame disappears. On emergent dualism, the soul is more like a spark that jumps from the candle and becomes an independent fire. The soul originates from the brain's physical processes, but once it comes into existence, it is a genuine immaterial substance with its own ontological status. In principle, it can survive the death of the body — if God sustains it.

Hasker argues that this view has important advantages over both standard physicalism and traditional substance dualism. Unlike physicalism, it affirms a genuine soul that can survive death. Unlike traditional substance dualism, it does not require God to create each soul individually through a special act of divine creation. Instead, the soul emerges naturally from the brain's development — a process Hasker sees as more scientifically and philosophically attractive.²²

I want to be fair to Hasker. His view is creative, philosophically sophisticated, and genuinely tries to account for both the scientific evidence about brain-mind dependence and the theological need for a soul that survives death. Among the "middle positions" between physicalism and traditional substance dualism, emergent dualism is the most sympathetic to the concerns that drive this book.

But emergent dualism has its own significant problems — and some of them are specifically Christological. Here are the ones that concern me most:

First, if Christ's soul emerged from Mary's developing brain during the natural course of embryonic and fetal development, then at some early point in the Incarnation, the Son was united to a human body that did not yet have a soul. The soul had not yet emerged. So what was the status of the Incarnation before the soul emerged? Was the Son united to a soulless body? Was His human nature incomplete? When, exactly, did the Incarnation become "complete"?

Second, does the soul's physical origin — the fact that it arose from natural biological processes rather than from a direct act of divine creation — compromise its fitness as a bearer of the hypostatic union? If the soul is a byproduct of brain development, is it the kind of thing that can be united to the divine nature of the eternal Son?

Third, there is the timing question. If the soul emerges from the brain at some point during development, then there is a period during which the embryo Jesus has no soul. The Incarnation has begun — the Son has assumed a human body — but the human nature is not yet complete. This seems to create an unacceptable gap in the hypostatic union.

We will develop these Christological problems in full in Chapter 25. For now, the point is that emergent dualism, while vastly superior to physicalism in its ability to affirm a genuine soul, introduces its own distinctive set of difficulties when applied to the Incarnation.²³

VIII. Hylomorphism (The Thomistic View)

Hylomorphism — from the Greek words hylē (ὕλη), meaning "matter," and morphē (μορφή), meaning "form" — is one of the oldest and most influential views of human nature in the Christian tradition. It originates with the ancient Greek philosopher Aristotle and was developed into a comprehensive Christian framework by the medieval theologian Thomas Aquinas in the thirteenth century. For much of the history of Christian theology, especially in the Catholic tradition, hylomorphism was the dominant view of human nature.²⁴

Here is the basic idea. On hylomorphism, the soul is not a separate substance in the way that Descartes imagined — an immaterial "thinking thing" that inhabits the body like a pilot in a ship. Instead, the soul is the form of the body. In Aristotelian philosophy, every physical substance is composed of matter and form. Matter is the raw material; form is the organizing principle that makes the matter into the kind of thing it is. The form of a dog is what makes a collection of atoms into a dog rather than a rock or a tree. The form of a human being — the human soul — is what makes a collection of atoms into a living, thinking, feeling human person.

On Aquinas's version, the soul is not just any form. It is a rational soul — a form capable of intellectual thought, moral reasoning, and relationship with God. And here is the crucial move: Aquinas argued that the human rational soul, unlike the forms of animals and plants, is subsistent. This means it can exist on its own, separated from the body, after death. An animal's soul cannot survive the death of its body because it depends entirely on the body for its operations. But the human rational soul, because it is capable of intellectual acts that transcend the material (thinking about abstract truths, knowing God), has a kind of independence that allows it to survive the body's destruction.²⁵

Here is a simple analogy. Think of the soul of a plant — let us call it the plant's "life principle." It is the organizing principle that makes a collection of carbon, hydrogen, oxygen, and nitrogen into a living plant rather than a pile of dead chemicals. When the plant dies, this organizing principle disappears. You cannot have a plant's "life" floating around without the plant. The form of the plant depends entirely on the matter it organizes. Now think of the human soul on Aquinas's view. It also organizes matter — it makes a body into a living human body. But it can also do something the plant's form cannot do: it can think about things that have no physical existence at all. You can think about the number seven, the concept of justice, or the nature of God. These objects of thought are not physical things. Aquinas reasoned that if the soul can perform operations that transcend the material (abstract thought), then the soul itself must in some sense transcend the material. And if it transcends the material, it can survive the material body's destruction.

This is why hylomorphism sits in a unique spot on our map. It is not straightforwardly physicalist — it affirms a soul that can survive death. But it is also not identical to the substance dualism of Descartes or the substance dualism I defend in this book. For Aquinas, the soul's natural state is embodied. The separated soul — the soul existing without a body between death and resurrection — is in an unnatural and incomplete condition. The soul without the body is not a complete human being. It is, in a sense, only half of what a human being is supposed to be. That is why the resurrection is necessary: the soul must be reunited with the body to restore full human nature.²⁶

I should mention that I am in significant agreement with Aquinas on this last point. Even on the substance dualism I defend, the separated soul is in an incomplete and unnatural state. God made us as body-soul composites, and the final goal of redemption is not permanent disembodiment but bodily resurrection. The intermediate state — the period between death and resurrection when the soul exists without the body — is real and conscious, but it is not the ultimate destiny of the redeemed. The resurrection is. On this, substance dualists and Thomistic hylomorphists stand together against physicalism, which cannot even get us to a conscious intermediate state, let alone explain the resurrection.

Where does hylomorphism fit in contemporary debates? As the contributors to Christian Physicalism? note, Aquinas's position resists easy classification in modern categories. Some scholars read Aquinas as a kind of substance dualist; others read him as closer to nonreductive physicalism. J.P. Moreland and Scott Rae argue that Aquinas's view is broadly consistent with substance dualism. Robert Pasnau has argued that Aquinas is best understood as a kind of nonreductive materialist. Eleonore Stump has suggested that his position might fit either nonreductive materialism or non-Cartesian substance dualism.²⁷

What matters most for our purposes is how hylomorphism handles the triduum mortis — the three days between Christ's death and resurrection. And here, Aquinas's own treatment actually supports the central argument of this book. Aquinas explicitly held that Christ's soul, separated from His body at death, continued to exist and remained united to the divine Person of the Son. During the three days in the tomb, the Son of God was united to Christ's separated soul and to His dead body, but the soul and body were not united to each other. The hypostatic union was maintained through the soul's continued existence.²⁸

This is extremely significant. Even Aquinas — whose hylomorphism differs from the substance dualism I defend — recognized that an immaterial soul is essential for the Incarnation to survive Christ's death. Without a soul that persists through death, the hypostatic union would have been dissolved at the cross. On this point, Aquinas and I are in complete agreement.

IX. Substance Dualism (The Author's Position)

Now we arrive at the position I hold and that this book defends: substance dualism. Substance dualism holds that a human being is composed of two distinct substances — a material body and an immaterial soul. The body is physical: it has mass, occupies space, is subject to the laws of physics and chemistry, and can be observed and measured by the methods of science. The soul is immaterial: it has no mass, does not occupy space in the way physical objects do, and cannot be detected by scientific instruments. Yet the soul is real — it is the seat of consciousness, thought, will, emotion, moral awareness, and personal identity.²⁹

On substance dualism, the soul can exist and function apart from the body after death. When a person dies, the body and soul separate. The body returns to the dust. But the soul — the person's core self, their "I" — survives. It continues to exist, to be conscious, and (on the Christian view) to be in fellowship with God. This is the intermediate state — the period between death and the final resurrection when the soul exists without the body, awaiting the resurrection of the body at Christ's return.

As Cooper explains with great clarity, if the doctrine of the intermediate state is true — if we are with Christ between death and resurrection, conscious and in fellowship with Him — then certain things necessarily follow. If I am with Christ after death, then "I" — my essential selfhood, my core personhood — must survive physical death. The being or entity that I am must continue to exist. And if my body is in the grave decomposing, then I — the surviving entity — must be something other than my body. I must be the kind of being that can exist apart from my body. This is what dualism means at its most basic level.⁴¹

Cooper is careful to emphasize what this does and does not require. It does not automatically require Platonic or Cartesian dualism with a radical metaphysical gulf between body and soul. It does not imply the Gnostic hostility toward the body. It does not require viewing body and soul as self-contained, independently functioning entities during earthly life. All it requires is that the person — the conscious "I" — can exist apart from the earthly body. That is minimally what dualism means. And any theory of human nature compatible with the Bible must provide for this possibility.⁴²

I want to be clear about what kind of substance dualism I hold. There are several varieties, and not all of them are equally defensible. The version I affirm is what John Cooper calls "holistic dualism."³⁰ This is critically important because it addresses one of the most common objections to dualism: that it treats the body as unimportant, a mere container for the soul.

Holistic dualism says this: body and soul are ontologically distinct — they are two different kinds of substance. But in life, they are deeply, intimately integrated. The soul is not imprisoned in the body like a driver in a car. Body and soul interact constantly. What happens to the body affects the soul, and what happens in the soul affects the body. You are not a soul who has a body, and you are not a body that has a soul. You are a body-soul unity — a single person composed of two substances that function together as a deeply integrated whole.

Cooper puts the point beautifully. The dualism of biblical anthropology, he argues, is part of the same picture that yields functional holism. Asserting only that biblical anthropology is dualistic is a half-truth. But so is the claim that it is merely holistic. As Cooper writes, only a combination like "holistic dualism" tells the whole story.³¹

One objection that physicalists frequently raise against substance dualism is the charge that it leads to a low view of the body — even to something like Gnosticism, the ancient heresy that treated the physical world as evil and the body as a prison for the soul. Warren Brown and Brad Strawn, for example, have argued in The Physical Nature of Christian Life that belief in dualism leads to a kind of spiritual individualism in which people focus inwardly on the soul rather than outwardly toward God and others.⁴³

I find this objection deeply unfair. As Charles Taliaferro has argued, dualism actually provides a strong basis for valuing embodiment. On Taliaferro's view, embodiment makes possible at least six types of virtue — sensory, agency, constitutional, epistemic, structural, and affective — that souls could not exercise without bodies. Similarly, Richard Swinburne argues that embodiment makes possible great goods such as the ability to make genuine free choices between good and evil and the ability to influence others and the physical world. Howard Robinson has defended a robust view of the soul's dependence on the body for psychological development. Far from demeaning the body, substance dualism affirms that the telos — the God-intended purpose — of the human soul is embodiment. This alone entails a rejection of Gnosticism.⁴⁴

Consider it this way: just because a dualist believes the soul is more valuable than the body does not mean the dualist believes the body has no value. One might value one's spouse more than one's parents, yet still deeply love and honor one's parents. The physicalist surely admits this principle when valuing God above creation while still highly valuing creation. The charge that dualism implies Gnosticism is a logical non sequitur.

And there is a further irony here. If anything, it is physicalism — not dualism — that struggles to account for the body's ultimate value. On physicalism, the body is all there is to a person. And that body will decompose at death. On substance dualism, the body matters precisely because God designed it to be the soul's partner — the instrument through which the soul engages the world, serves others, and worships God. The body is not a disposable shell; it is a beloved companion that will be resurrected and glorified at the last day. Dualism gives us more reason to value the body, not less, because it grounds the body's importance in God's design for the body-soul unity.

The philosophical case for substance dualism rests on several powerful arguments, which we will develop in full in Chapter 4: the argument from qualia (subjective conscious experience cannot be reduced to physical brain states), the argument from personal identity (you remain the same person even though your body's atoms are constantly being replaced), the argument from intentionality (mental states are "about" things in a way that no physical state can be), and the argument from the unity of consciousness (your experience is unified in a single "I" that no collection of neurons can explain). For now, I will simply note that these arguments are formidable, and that the major philosophical defenders of substance dualism — including J.P. Moreland, Richard Swinburne, and Charles Taliaferro — have shown that they withstand the most common objections.³²

What are the implications for survival after death? On substance dualism, the answer is clear and straightforward. At death, the body and soul separate. The body dies and begins to decompose. But the soul — the conscious, personal, experiencing self — continues to exist. The person has not been destroyed. They have been disembodied. This is not their ideal or natural state — God made human beings as embodied creatures, and the final goal is bodily resurrection. But the soul's survival ensures that personal identity is maintained continuously from life through death to resurrection. There is no "gap," no period of nonexistence, no need for God to re-create the person from scratch.

X. Distinguishing Substance Dualism from Cartesian Dualism

Before we move on, I need to address a common confusion. Many people — including some theologians and philosophers — hear "substance dualism" and immediately think of René Descartes. And since Descartes's specific version of dualism has well-known problems, they assume that all substance dualism shares those problems. This is not the case.

Descartes held that the body and soul are two completely separate substances that are radically different in nature. The body is "extended substance" — it takes up space. The mind (or soul) is "thinking substance" — it has no spatial properties whatsoever. The famous difficulty with Descartes's view is the "interaction problem": if the mind has no spatial properties at all, how does it interact with the body? How does an entirely nonspatial thought cause a spatial body to move?³³

This is a legitimate philosophical difficulty for Cartesian dualism, and I do not want to minimize it. But I want to point out two things. First, the interaction problem is not unique to dualism. Physicalism has its own version — the "hard problem of consciousness," as philosopher David Chalmers calls it: how does a physical brain produce subjective conscious experience?³⁴ Both sides have unsolved puzzles. Second, not all substance dualists accept Descartes's specific framework. The holistic dualism I hold — following Cooper, Moreland, and others — does not require the radical separation of body and soul that Descartes proposed. Body and soul are deeply integrated and constantly interacting. The interaction itself is a basic, irreducible feature of reality, not something that needs to be explained in terms of something more fundamental.³⁵

We will address the interaction problem and other objections to dualism in full in Chapter 4. For now, the key point is this: substance dualism is a broad family of views, and the specific version I hold — holistic dualism — is significantly different from Descartes's version.

XI. Wilkinson's Methodological Principle: Christology Norms Anthropology

Before we conclude this survey, I want to return to a methodological principle that I believe should govern the entire discussion. Michael Wilkinson, in his important work Crowned with Glory and Honor, argues for what he calls a "Chalcedonian anthropology" — an understanding of human nature that takes its starting point not from philosophy or science but from Christology.³⁶

Wilkinson's argument runs like this. The Council of Chalcedon (AD 451) defined Christ's human nature as a complete human nature — body and soul. The councils that followed, especially Constantinople II (553) and Constantinople III (681), reinforced this by condemning Apollinarianism (the denial that Christ has a human rational soul) and affirming dyothelitism (that Christ has two wills, a divine will and a human will). If Christ's human nature — as defined by the authoritative, Spirit-guided ecumenical councils — includes both a body and an immaterial soul, then human nature as such includes both a body and an immaterial soul. Christ's human nature is the pattern and norm for understanding all human nature.

This is an enormously important insight. Most contemporary debates about human nature proceed in the opposite direction. They start with philosophical or scientific considerations — What does neuroscience tell us? What does physics allow? What is the simplest metaphysical theory? — and then they apply those conclusions to Christ. They decide that human beings are purely physical organisms and then try to fit Christ into that framework.

Wilkinson argues that this gets things backwards. The proper Christian method is to start with what we know about Christ — the most fully and perfectly human being who has ever lived — and let that inform our understanding of all human nature. As Wilkinson puts it, the human nature that the councils defined Christ as possessing tells us what human nature is. If Christ has a body and a soul, then so do we. Christology norms anthropology.³⁷

I find this principle compelling, and it will recur throughout this book. It means that the debate about human nature is not merely an abstract philosophical argument that happens to have Christological implications. It means that Christology — what we know about the Person of Christ — has direct authority over how we understand human nature. And since the councils clearly defined Christ as having a complete human nature with an immaterial rational soul, any anthropology that denies the soul is in tension not just with philosophy but with Christology itself.

This does not mean, of course, that philosophy and science are irrelevant. They are not. The philosophical arguments for substance dualism (Chapter 4) and the empirical evidence from veridical near-death experiences (Chapter 5) are important and valuable. But they confirm what Christology already tells us: human beings are body-soul composites.

It is worth noting that Wilkinson goes further than I do in his anthropological proposal. He develops what he calls a "person-nature" distinction in which the human person — understood as a personal hypostasis (ὑπόστασις), or subsistent individual — is an ontological reality distinct from the body-soul nature. On his model, the human person is not identical to the soul (as some versions of substance dualism hold) but is the subsisting subject who possesses the body-soul nature.³⁸ While I find Wilkinson's constructive proposal fascinating, the key point for our purposes is his methodological principle: Christology should shape our anthropology. On this, I am fully in agreement.

XII. A Comparison of the Models

Now that we have surveyed each major model, it will be helpful to see them side by side. The following table compares how each view handles four critical questions: (1) Can the person survive bodily death? (2) Does the view allow for a conscious intermediate state? (3) Does the view preserve the hypostatic union during the triduum mortis? (4) Does it preserve personal identity at the resurrection?

The pattern is unmistakable. Every form of physicalism — reductive, nonreductive, constitution, and emergentism — fails on all four criteria. They cannot provide for genuine survival after death without appeal to divine re-creation. They cannot account for a conscious intermediate state. They cannot preserve the hypostatic union during the triduum mortis. And they create a devastating personal identity problem at the resurrection.

Emergent dualism fares better because it affirms a real soul, but it introduces the problematic question of the soul's origin and its timing within the Incarnation. Hylomorphism preserves the key Christological requirements — Aquinas himself showed how — but it treats the separated soul as an unnatural and incomplete state. Substance dualism, I believe, provides the most complete and coherent foundation for all four criteria.

XIII. The Rise of Christian Physicalism: A Brief Historical Note

Before we draw our conclusions, it is worth asking: how did we get here? For most of Christian history, the dominant view of human nature was some form of dualism — whether the substance dualism of the Augustinian and Reformed traditions, the hylomorphic dualism of the Thomistic tradition, or the broader consensus reflected in the ecumenical creeds and councils. The idea that human beings have immaterial souls that survive bodily death was not controversial. It was assumed.

What changed? As Wilkinson traces in Crowned with Glory and Honor, two challenges to substance dualism emerged over the past several centuries.⁴⁶ The first was a biblical-theological challenge. Beginning with the historical-critical movement in the nineteenth century, some scholars argued that the traditional dualist reading of Scripture was the result of "Hellenization" — the illegitimate importing of Greek philosophical ideas into biblical interpretation. On this reading, the Hebrew Bible teaches a holistic, monistic anthropology, and the dualist language of the New Testament was a later Greek influence that distorted the original Hebraic worldview. The second challenge was scientific. Advances in neuroscience and physiology revealed an extensive bilateral dependence between the mind and the brain. Brain damage affects personality. Drugs alter mood and cognition. Stimulating specific brain regions produces specific mental experiences. To many scholars, this seemed to remove any scientific basis for believing in an ontological distinction between mind and brain.

Together, these two challenges produced what Wilkinson describes as a "precipitous growth of physicalism" in twentieth- and twenty-first-century Christian anthropology.⁴⁷ Some estimates suggest that scholars have offered no fewer than 130 different views on the makeup of human beings in the last century alone. The sheer number of physicalist models might seem to signal a consensus rejection of dualism.

But appearances can be misleading. As Kevin Corcoran himself has acknowledged, the mind-body problem "remains wide open."⁴⁸ Far from disappearing, substance dualism has moved from dominance to vigorous debate. Accomplished philosophers like Moreland, Swinburne, Taliaferro, and Plantinga continue to defend it. Cooper's Body, Soul, and Life Everlasting has shown that the "Hellenization" narrative is historically inaccurate — the biblical writers did not need to borrow from the Greeks to affirm a body-soul distinction that was already embedded in their own Hebraic traditions. And the neuroscience argument, while impressive, confuses dependence with identity. The fact that the mind depends on the brain for its normal operation does not prove that the mind is the brain, any more than the fact that a radio depends on its antenna for reception proves that the signal is the antenna. We will develop this "radio analogy" more fully in Chapter 4.

The point for now is simply this: the rise of Christian physicalism is a real and significant development, but it does not represent a settled consensus. It represents an ongoing, vigorous debate — a debate in which, I believe, the evidence ultimately favors substance dualism.

XIV. Why This Matters for the Rest of the Book

Let me step back and explain why this survey is essential for the argument of this book.

The central thesis of this book is that physicalism about human nature is incompatible with orthodox Christology. That is a strong claim, and it needs to be demonstrated carefully. Before we can demonstrate it, the reader needs to understand exactly what physicalism claims. Not a caricature of physicalism. Not a straw-man version. The real thing — in its strongest and most sophisticated forms, defended by its most capable Christian advocates.

That is what this chapter has attempted to provide. We have looked at reductive physicalism, nonreductive physicalism, the constitution view, and emergentism — and we have seen that all of them, despite their differences, share one fatal feature: they deny the existence of an immaterial soul that can survive the body's death. This shared denial is what makes all of them incapable of supporting orthodox Christology, because orthodox Christology requires that Christ's human soul survived His death on the cross.

We have also looked at the "bridge" positions — emergent dualism and hylomorphism — which affirm a soul but differ from substance dualism in important ways. And we have seen that even these views, while far superior to physicalism, face their own distinctive challenges when applied to the Incarnation.

In the chapters that follow, we will build the positive case for substance dualism from Scripture (Chapter 3), philosophy (Chapter 4), and empirical evidence from veridical near-death experiences (Chapter 5). Then, in Parts II through V, we will turn to the Incarnation itself and show in devastating detail exactly how physicalism fails — at the cross, during the triduum mortis, at the resurrection, at the ascension, and in the permanent Incarnation of the glorified Christ.

But all of that rests on the foundation we have laid in this chapter: a clear, fair, and comprehensive understanding of what the various models of human nature actually claim, and why the differences between them matter so profoundly for the Person and work of Jesus Christ.

XV. Conclusion

We have covered a lot of ground in this chapter. We have surveyed seven major models of human nature — from the most reductive form of physicalism to the holistic substance dualism that I defend. For each model, we have asked what it claims, why its defenders find it attractive, and what it means for survival after death and for Christology.

The picture that emerges is sobering. Every form of physicalism — reductive, nonreductive, constitution, emergentist — denies the existence of an immaterial soul. And every one of them, as a result, faces devastating consequences when applied to the Incarnation. If Christ has no soul, then His death is the end of His human nature. The hypostatic union is dissolved. The descent to the dead is impossible. The resurrection creates a personal identity crisis. The permanent Incarnation is undermined.

These are not minor problems. They are not technical difficulties that clever philosophical maneuvering can resolve. They are fundamental, structural failures that flow directly from the denial of the soul. And they strike at the very heart of what the ecumenical councils declared about who Jesus is and what He did for us.

I do not say this to be harsh toward physicalists, many of whom are sincere and thoughtful Christians. I have tried throughout this chapter to present their views fairly and to acknowledge the genuine motivations behind their positions. The desire to take science seriously, the concern about Hellenistic contamination of biblical interpretation, the worry about Cartesian problems with soul-body interaction — these are real and understandable concerns. But I believe that the evidence — biblical, philosophical, empirical, and Christological — points decisively toward substance dualism. The soul is real. It survives death. And without it, the Incarnation cannot be preserved.

We have also seen that Wilkinson's methodological principle — that Christology should norm anthropology — reframes the entire debate. If we start not with philosophy or neuroscience but with what the councils defined about Christ's human nature, the answer is already given to us: Christ has a complete human nature consisting of a body and a rational soul. If that is what human nature is for Christ — the perfect, paradigmatic human being — then that is what human nature is for all of us. Physicalism does not merely face philosophical difficulties. It faces Christological impossibilities.

In the next chapter, we will turn to the biblical evidence for this conviction. We will see that from Genesis to Revelation, the Bible consistently teaches that human beings are body-soul composites and that the soul survives the body's death. We will examine the key Hebrew and Greek terms, engage with the physicalist counter-readings of those texts, and show that the biblical witness — read carefully and in context — supports substance dualism. The foundation for everything that follows in this book is about to be laid.

And then, beginning in Part II, we will turn our attention to Christ Himself — His deity, His humanity, His inner life, His death, His descent, His resurrection, and His ascension. We will see that at every point, the biblical and conciliar portrait of Christ presupposes what the soul-denying physicalist cannot provide: a complete human nature with a genuine immaterial soul that survives death, preserves the hypostatic union, and sustains the Incarnation forever.