Philosophers ask questions about all sorts of things. We wonder about the nature of reality, the existence of God, the possibility of gaining knowledge of the world, and the basis of our moral inclinations. But philosophers also ask questions about persons in general and what it means to be a human person in particular. What exactly is a human being? What makes us unique? And how is it that we manage to continue existing across time? These might sound like bizarre or even unnecessary questions, but a casual reflection on our lives in the world suggests that these questions are highly important. What are we exactly? How are we put together? What is my relationship to my body? And is there more to me than just my body?
Questions like these have been a central topic of debate throughout the history of philosophy, but especially in contemporary philosophy. Generally speaking, substance dualist philosophers—such as Plato in the ancient world and the seventeenth-century philosopher René Descartes—made a sharp distinction between bodies and souls (or minds), suggesting that they were two distinct kinds of things. In addition to this, Plato and Descartes argued that persons were to be identified with the soul (or mind) and not the body. This view has been widely held throughout most of philosophical history and continues to have able defenders to this day.1 Nevertheless, Plato and Descartes’s view has not been the only one. In the modern period, for example, philosophers like Locke and Hume rejected such substantival views, arguing instead that persons are nothing more than a cluster of psychological dispositions, beliefs, and memories. Still later, a long list of other philosophers from modernity to the present have argued that human persons are material beings through and through.
The purpose of this chapter is not so much to trace the history of these debates, as important as they may be. Rather, the purpose is to sift through the various topics, concepts, and questions that guide philosophers in the current discussion and to help students find their footing in such discussions. To do this, we will first lay out some basic terms and concepts at play in the conversation, highlighting some of the most important questions on the subject along the way. After that, we will offer a quick survey of the most common positions on the questions of human nature and constitution.
Basic Terms and Concepts
In one sense, terms like “mind,” “soul,” “body,” “person,” and “human person” seem to be rather straightforward and understandable. We use them every day with ease, and we know what they mean when people use them in general conversation. But other terms, like “substances,” are less familiar and can cause confusion. Furthermore, even with the more familiar terms like “minds,” “souls,” and “persons,” philosophers tend to use them in unique ways and with layers of nuance and technicality. Hence, given the nuance and technical nature of the philosophical debate around these issues, it is important to begin the discussion with a quick survey of how they are used in philosophical discourse.
Substances
The notion of “substance” is as old as philosophy itself and comes into play within the broader field of metaphysics. It was first introduced by Aristotle, but similar notions can be found with thinkers before him. According to Aristotle, a substance is something that is composed of both matter and form. Consider a cup that you drink from. What is it that makes it a cup? Aristotle would describe the cup as composed of the material stuff of wood or heat-cured clay as well as the form that is imposed on the material to give it the structure of a cup. Only when the two come together do we have the substance of a cup.
As we saw in chapter 9, discussions about substances have evolved over time. Contemporary philosophers, for example, tend to think about substances differently than Aristotle conceived of them. In these discussions, philosophers typically focus their attention on the kinds of criteria that must be met in order to identify a thing as a substance. According to Peter Simons, various factors have been suggested in recent history. Summarizing the discussion of Aristotelian substance from chapter 9, four distinct criteria seem to be most common. First, substances are often thought of as the bearers of properties. Consider, once again, Rosie the chicken. Notice how I mentioned that she is a chicken. That is to say, Rosie has the property of being a chicken. As such, she is the bearer of a property. Metaphysicians regularly note that this is a major feature of substances. They bear properties or qualities but are not themselves a property or quality of some other thing.
Second, substances can be conceived as allowing for individuation. In other words, substances allow for things to be individuated and distinct from other things. Consider the two chickens Rosie and Ronnie. They are two distinct chickens, not one. Each individual chicken is a substance that is distinct from the other, no matter how similar they appear to be physically. As substances they are individuated from each other.
Third, substances are the kinds of things that can exist on their own. This is not to say that they don’t have to have a cause for their existence. Rather, it is to say that their existence does not ride on some other thing such that if that other thing ceased to exist, then the substance would too. Consider the shadow of a tree. If the tree were not there to block the rays of the sun, then surely the shadow would not be there. In this case, the shadow cannot exist on its own. Substances are different since they are the kinds of things that don’t need some other thing to exist. Rosie sits by herself and does not depend on anything else around or beside her.
Finally, substances can be thought of as things that are capable of surviving changes. That is, a substance can sustain a change of some kind and continue to be what it is and continue to be the one that it was.2 Again, Rosie is helpful. When Rosie first hatched from her eggshell, she had yellow feathers. But as she grew and developed, she lost her yellow feathers and replaced them with reddish brown feathers. Did Rosie change in some way? Yes, of course. Yet is she still a chicken? Yes, of course. Is she the same chicken she once was? Again, yes, of course! These four criteria are helpful for our purposes in this chapter since much of the debate on the topic of human persons revolves around the validity of substance dualism.
Minds and Souls
Setting forth the meaning of words like “minds” and “souls” in the current debates is a little more difficult. For starters, these terms can be used interchangeably by theologians and philosophers. This interchange is somewhat understandable since there is indeed much overlap in what is meant by each term. But they do not always mean exactly the same thing. Another difficulty comes from the fact that each term seems to carry a different level of meaning depending on the particular view held by the person treating the question. In other words, different theories of mind define minds differently; so also different views of the soul define souls differently. What philosophers and theologians mean by these terms depends at least in part on who is speaking and the view they espouse. Despite these tendencies, however, we shall offer a quick survey of the ways these terms are used.
So what are minds? At minimum, minds are entities that facilitate rational processes and process intelligent functions. But if this is all they are, then there is no reason to say that humans, animals, angels, or divine persons are all that could qualify as having minds. On this view, we could also include computers as minds. For most philosophers, however, this definition is not enough. Most go beyond this to include other important features in their conception of minds. Most views of the mind suggest that minds are thinking things, thus capable of reflection and metacognition. Regardless of what kinds of stuff minds are composed of—physical brains or spiritual substances—most philosophers throughout history have generally agreed that minds are the kinds of things that think, reason, and reflect. But this raises the question of what exactly it is that composes minds, and this takes us into another view of minds. As suggested above, while some believe that physical brains are capable by themselves of facilitating such metacognitive thought, philosophers like Plato, Descartes, and many more have argued that only immaterial substances could ever think. And so, for Plato and Descartes, minds are distinct from physical brains and physical bodies and are instead composed of something nonphysical.3 On this view, minds have a spiritual element over and above the brain, even if minds are intimately connected with brains.
With this in view, it is easy to see why terms like “mind” and “soul” are used interchangeably. Those employing the term “soul” typically use that term to refer to immaterial substances that are capable of thought, reflection, desire, intention, direction, and conscious experiences. As we shall see below, this is the view espoused by substance dualists. But once again, this is not the only way the word “soul” is used. For hylomorphists (Greek: hylē = matter; morphē = form), a soul is not actually a spiritual immaterial substance. Rather, it is the substantial form—the organizing principle that gives life and structure to the physical body—of the body that it gives life to.4
Persons and Human Persons
Most of us never wonder what it means to be a person. We don’t struggle to recognize and categorize the various beings we encounter into the proper categories in which they belong. When we meet a new dog, for example, we don’t wonder if it is a person. We recognize it as a dog and would likely dispute any suggestion by others that the dog is a person. But if we had to dispute the claim that dogs are persons, how would we do it? What does the dog lack that we possess? This question forces us to ask a broader question: What exactly is a person?
Some initial answers might go as follows. Perhaps persons are beings or entities with minds and therefore capable of thought and reflection as described above. While most philosophers would agree that having a mind is a necessary condition for persons, they would also tend to agree that it is not a sufficient condition for personhood. That is, having a mind may be a minimal criterion but would not by itself make something a person. In short, while animals like dogs clearly and significantly differ from human beings in their mental life, it is also the case that animals think. Perhaps, then, one might say that persons have conscious experiences like tasting sugar or hearing wind blow and that this is what makes us persons. But again, it surely seems as though dogs do the same thing. They clearly like certain kinds of foods and respond to the sound of our voices. It certainly looks as though they have some kind of conscious experience. Or perhaps one may say that the difference between us and dogs that makes it possible to say that humans are persons and dogs are not is that humans are just more intelligent. While this is certainly true, it again doesn’t seem to convey the distinction between animals and persons. It seems like there is something more.
Lynne Rudder Baker’s work is helpful on this point. She argues that persons have two distinct qualities that other nonperson animals don’t: intentional states and first-person perspective. The intentional-states criterion requires that, at minimum, a person has mental states like desiring, intending, and planning. So, for example, persons are the kinds of things that desire to get married, intend to do so, and then develop a plan to go about accomplishing this. But here again, this criterion is clearly not a sufficient condition for personhood since many animals demonstrate these capacities on a regular basis. Baker adds an additional condition that is the most important one for us to consider. According to Baker, a person is some kind of being that has first-person perspective. She says, “To be a person—whether God, an angel, a human person, or a Martian person—one must have the capacity for a first-person perspective.”5 She explains this further, saying, “The defining characteristic of person is a first-person perspective.”6 But what does this mean? In other words, first-person perspective requires more than me being able to have desires, intentions, and plans: it is a metacognition about myself that requires me to realize that it is I who has such desires, intentions, and plans. It is this first-person awareness of my mental states that seems to be the key for Baker’s account. Baker’s criteria seem to get at something that truly differentiates persons from nonpersons. Even still, we might add at least one additional component to our understanding of persons: moral inclinations. Persons are the kinds of beings that operate and act in moral categories. We have a sense of oughtness and responsibility that drives and shapes us. This is a major difference from animals and nonpersons. Thus we suggest that persons are beings with intentional states, first-person perspective, and moral inclinations.
Notice that the above discussion is about persons in general. It does not distinguish specific kinds of persons. Because of this, we need to say something more with regard to what it means to be a human person. Nevertheless, what we have said thus far about persons in general will apply to the question of human persons, even if there is more to say about this specific case. In addition to being entities with intentional states, first-person perspective, and moral inclinations, human persons are persons who are related in some way to human bodies. The relationship of person to the human body is a matter of debate between the various positions. For materialist views, that relationship is very strong. On these views, the human person either is identical to the living human body or is at least constituted by the living human body. According to substance dualist views, however, the relationship to the human body is not as strong. On this view, the human person is just the soul/mind, and its relationship to the body is one of possession. In other words, the person is the soul and has a body.
Scores of views might be enumerated here, but three major views have tended to dominate the debates of the past and the present: (1) substance dualism, (2) materialism and physicalism, and (3) some middle position between the first two that we might call hylomorphism. We shall see the differences of these views as we go forward.
Substance Dualism
The most widely held view throughout philosophical history is called substance dualism. This was the view of Plato and, later, Descartes. Plato, Descartes, and others who hold this view typically make two distinct ontological claims regarding human constitution. First, substance dualists make what we might call a stuff distinction claim. On this view, there are two distinct kinds of stuff with regard to human persons: physical bodies and nonphysical souls or minds. Bodies and souls are radically different from each other and must be thought of as fundamentally different substances. Being different substances, the body and the soul have different identities, bear different properties, survive different kinds of events, and can exist apart from each other.
Substance dualists, however, make an additional claim, and this is the one that is most essential to understand. The second claim is the person/soul identity claim: while there may be two distinct kinds of stuff, persons are distinct from their bodies and identical to their souls. In this claim, in other words, substance dualists contend that human persons are not their physical bodies. Human persons may have physical bodies, but they are not their bodies. Instead, substance dualists argue that human persons are souls that inhabit or possess their bodies. As J. P. Moreland and Scott Rae suggest in their account, “Human persons are identical to immaterial substances, namely, to souls.”7 Or as Stewart Goetz puts it, “One of the things that I, as an ordinary person, believe about myself is that I am a soul that is distinct from my physical (material) body.”8
Like other views, substance dualism has its strengths and weaknesses. This view, for example, seems to have a rather easy time accounting for things like conscious experience and personal persistence across time. Consider the experience we have when we taste a soda. In this case there clearly are particular kinds of physical events that take place on a chemical level on the tongue and in the mouth. With these, there are also corresponding brain events in the neural firings of the brain. Interestingly, however, the actual experience of tasting the soda doesn’t appear to be reducible to the physical events of the mouth or the brain event in the neurons. To account for the actual experience of tasting, it looks as though something beyond the physical body and brain is required. John Searle puts it this way: “Materialists have a problem: once you have described the material facts in the world, you still seem to have a lot of mental phenomena left over. Once you have described the facts about my body and my brain, for example, you still seem to have a lot of facts left over about my beliefs, desires, pains, etc.”9 Searle goes on to state that this problem has often led materialists to try to simply explain consciousness away or eliminate consciousness. But this is rather problematic since consciousness is so obviously real. Searle observes that getting rid of consciousness “is not an easy thing to do. It sounds too implausible to say right out that pains and beliefs and desires don’t exist, though some philosophers have said that.”10 Substance dualists have no such problem. In their ontology, there is plenty of space for the mental life and conscious experience, and it seems far easier to account for such things with the existence of the soul.
Substance dualists also appear to have an easier time accounting for the persistence of the person across time. Consider what happens in our experience. Take, for example, Bernie’s development and change throughout his life. Bernie was born in 1976, his body was twenty-one inches long, he weighed six pounds and thirteen ounces, and he had no hair. Of course, his body didn’t stay that way. It grew and changed over time as he ate food and his body metabolized it. By the time he was three years old, he was forty inches tall, weighed thirty-eight pounds, and had curly blond hair. The process of growth and development continued over time until he reached his full growth potential of five feet, eleven inches in height, weighed two hundred pounds, and had thick brown hair that was still a little curly.
Two things are interesting about this growth process. First, to put it roughly, his body experienced significant changes over time and was even composed of different parts along the way as his body metabolized food and discarded old parts that wore out. Second, despite these changes Bernie continued to be exactly the same person he was at the earlier moments of life, when his body was very different. That is, Bernie of 1976 and Bernie of today are exactly the same person. What allowed for Bernie to continue being Bernie even though his body was constantly changing? Substance dualists have a rather straightforward and easy answer to this question: his soul. No matter what one thinks about substance dualism in general, and despite what other materialistic answers might be given to the question of personal persistence across time, one has to respect the simplicity and elegance of the substance dualist’s answer to this question.
But, as is well noted throughout history, substance dualism seems to face a rather perplexing issue known as the mind-body interaction problem. This problem involves a seeming impossibility of immaterial minds interacting with the material body. If, as substance dualists say, bodies and souls are radically different substances, one being material and the other being immaterial, how is it that the two interact with each other? As we consider the nature of bodies and souls as described by substance dualists, our normal understanding of causation seems to go out the window.
Consider the case of two dominoes that fall in a causal sequence. Why is it that domino B fell? It fell because domino A caused it to fall when it fell and hit domino B. And how exactly did A’s hitting B cause B to fall? It caused it to fall by (1) coming into contact with B and (2) transferring energy from itself into B. Can this understanding of causation work for bodies and souls? It doesn’t seem so, since immaterial souls have no mass and do not take up space. Therefore the body and the soul (1) cannot come into contact with each other and (2) cannot transfer energy to each other. Or at least so it seems. Perplexing questions like these have caused philosophers over the centuries to reject substance dualism. In Descartes’s own time, Princess Elisabeth of Bohemia raised this very concern: “I admit that it would be easier for me to concede matter and extension to the soul than to concede the capacity to move a body and to be moved by it to an immaterial thing.”11 In other words, for Princess Elisabeth, the interaction problem was so significant that she found it easier just to believe that minds/souls were material things than it was to believe that an immaterial thing could interact with material objects. To this day, many philosophers continue to think that this concern is a defeater for substance dualism. But, of course, defenders of the position disagree. The debate rages on!
Generally speaking, in philosophical discussions of human persons the terms “materialism” and “physicalism” are synonymous and interchangeable. Some may make certain subtle distinctions between the two, but we shall use them interchangeably in what follows. Materialists take a much different approach to the question of human persons than substance dualists. Specifically, they reject the existence of immaterial substances like souls or minds. While distinct materialistic views share this belief in “material monism,” the actual details of distinct views can vary considerably. We won’t have the space to address all of them, but a sampling of some of the most common views can be offered.
Psychological Continuity Model
One notable view, adopted by Descartes’s contemporary John Locke (1632–1704), is called the psychological continuity model of persons. This view rejects the notion of immaterial souls/minds and affirms the idea that the “self” is a bundle or cluster of psychological properties composed of memories, beliefs, and psychological dispositions. Moreover, some particular “self,” or we could say more generally “person,” persists across time as long as there is psychological continuity across time. Locke famously says:
For as far as any intelligent being can repeat the idea of any past action with the same consciousness it had of it at first, and with the same consciousness it has of any present action; so far it is the same personal self. For it is by the consciousness it has its present thoughts and actions, that it is self to itself now, and so will be the same self, as far as the same consciousness can extend to actions past or to come, . . . with . . . the same consciousness uniting those distant actions into the same person, whatever substances contributed to their production.12
That is, as long as the psychological bundle of properties—beliefs, desires, dispositions, and so forth—continue to exist, the person continues to exist.
Eliminativism
In recent philosophical history, a more radical materialist ontology known as eliminativism has been adopted by some philosophers. This is a radical view because it suggests that the best way to handle mental properties and states is simply to deny them altogether, or at least to deny the vast majority of them. In this model, there are no such things as “beliefs,” “pains,” “desires,” or “feels.” Some advocates of this view would even say that there is no such thing as free will or the self. On this account of minds, there are only brains and brain events. This view is called eliminativism because it eliminates minds and mental properties entirely.
Technically speaking, by eliminating the mental, this view says that no one ever feels pain or tastes anything. As one might imagine, this is not a very popular view among materialists, simply because it seems so counterintuitive. Even though they universally reject immaterial substances, materialists generally recognize the reality of our experiences of pain, tastes, hopes, and joys. The eliminativist’s attempt to get rid of such things just doesn’t seem to work.
Reductionism and Identity Theory
Other materialists offer a slightly less radical account of the mental. Reductionists, for example, do not deny that we feel pain, taste sugar, or have hope. Rather, they simply reduce those things, which are typically thought of as mental events or properties, to brain events or physical properties. That is, those phenomena are just, or are nothing but, physical properties or events in the brain. One very common expression of this is called identity theory, which claims that minds and brains are identical to each other. To describe a mind is just to describe a brain. Hence our understanding of the mind is nothing more than our understanding of the brain. On the surface, it may seem as though the reductionists and identity theorists are saying exactly the same thing as the eliminativist, but they actually aren’t. Pete Mandik offers a helpful comparison:
The simple form of mind-brain identity theory says that pains are nothing but a certain kind of brain state—c-fibers firing. The simple form of eliminative materialism says that there are no pains—there are only c-fibers firing. Both theories agree that c-fibers firing exist. But do both agree that there are no pains, that pains do not exist? No, they do not, and this is the key difference between them. The mind-brain identity theorist’s statement in terms of “nothing but” may make it seem like the existence of pains is being denied, but this is not so. The “nothing but” claim—the claim that pains are nothing but c-fibers firing—is not telling us that pains are nothing at all. Instead, it is simply saying that pains are nothing additional, they are nothing beyond c-fibers. . . . In contrast, the eliminative materialist is outright denying that pains are identical to c-fibers firing. Pains aren’t identical to anything at all—they don’t even exist according to the eliminative materialist.13
As Mandik makes clear, reductionist views like identity theory have some similarities to eliminativist accounts of the mind, but identity theory is a less radical view that doesn’t reject the commonsense notion that pain and other such experiences are real. It does, however, reduce mental aspects of our lives to the physical events and components of our brains. In the end, it maintains that everything is reducible to, and thus explainable by, the physical.
Nonreductive Physicalism
A much more common materialist view, at least among Christian materialists, contends that the reductive account also goes too far. They may agree with their fellow materialist that immaterial souls do not exist and that only material substances do, but they reject the idea that everything—namely, the mental—is reducible to the physical. That is to say, on their view there may be only one kind of stuff that accounts for human beings on a basic ontological level, but that doesn’t mean that mental stuff is reducible to brain stuff. This nonreductive physicalism is a form of physicalism, since it holds that, ontologically, human persons are nothing more than living physical organisms. At the same time, however, it does not reduce the mental to physical objects, events, or states. On this view, the mental is something distinct from the physical. Nancey Murphy, one of nonreductive physicalism’s most able defenders, says that when applied “to the specific area of studies of consciousness, it denies the existence of a nonmaterial entity, the mind (or soul) but does not deny the existence of consciousness (a position in philosophy of mind called eliminative materialism) or the significance of conscious states or other mental (note the adjectival form) phenomena.”14 She then adds, “In brief, this is the view that the human nervous system, operating in concert with the rest of the body in its environment, is the seat of consciousness (and also of human spiritual or religious capacities). Consciousness and religious awareness are emergent properties and they have a top-down causal influence on the body.”15
Several features of Murphy’s description are worthy of comment. First, notice that this view affirms conscious experiences. It does so without reducing the content of conscious experiences, mental content, or mental properties to physical brain states. As often pointed out, this view holds that while there may not be a dualism of substances, there is a dualism of properties. In other words, this view rejects substance dualism but embraces property dualism. Property dualism claims that mental properties are distinct from physical properties and that mental events are distinct from brain events, even if they occur in conjunction with each other. In the philosophical literature, the kind of mental properties we have in view here are often referred to as qualia, which is the Latin for “qualities.” In our conscious experiences of things, we experience qualities like sweetness, redness, bitterness, or coldness. Thus there is something that it is like, a mental experience, that we possess in these moments. Property dualism affirms that mental properties and qualia are not reducible to physical brain events, but it does so while also maintaining physicalism.
Second, these properties are emergent in that they arise out of the complex neurological system within the brain. Third, once such properties have emerged, they exercise a downward causation on the lower systems of the brain and the rest of the body. This understanding of downward causation, sometimes called top-down causation, is best understood by setting it in contrast to bottom-up causation. As Murphy and Brown explain, bottom-up refers to “the assumption that behavior of an entity is determined by the behavior (or laws governing the behavior) of its parts.”16 By contrast, a downward-causation model suggests that “phenomena at some higher level or organization of a complex system had a downward causal influence on the events that were being studied at a lower level.”17
Functionalism
Another very popular view among materialist philosophers is known as functionalism. Though functionalism is technically noncommittal about the number of substances involved in a human person, the overwhelming majority of those who hold this view come from the materialist camp. Generally speaking, functionalists think the “number of substances” question is the wrong question. In their view, the better and more important question is, What is a mind? And as their name implies, functionalists define minds as those entities capable of intelligent function, contending that there are any number of entities—humans, computers, machines, and so forth—that might qualify as minds. A helpful illustration of the functionalist conception of minds is the illustration of a hand and a fist. What exactly is a fist? It is a hand that punches. When the hand is balled up into a fist, no new thing comes into existence. Rather, all that happens is that the hand now takes on the function of punching. The same is the case with a brain. When it thinks, no new thing comes into existence. Rather, the brain simply takes on the function of thinking. As already implied, this view of minds raises questions about machines, robots, computers, and much more. Do computers have minds? Are they able to think? While some philosophers believe this is possible, others continue to resist the notion: it is not at all clear that computer processing comes anywhere close to achieving the same kind of thing humans do when we think, reflect, desire, and deliberate.
Constitutionalism
One final materialist view is worth considering. Constitutionalism is the view that human persons are constituted by their physical bodies even if they are not identical to them. Kevin Corcoran offers an illustration to help clarify the point: “For example, statues are often constituted by a piece of marble, copper, or bronze, but statues are not identical with pieces of marble, copper, or bronze that constitute them. Likewise, dollar bills, diplomas, and dust jackets are often constituted by pieces of paper, but none of those things is identical with the piece of paper that constitutes it.”18
Like other materialists, constitutionalists reject the idea of there being immaterial substances like souls. On a brute ontological level, there is nothing beyond the physical body that constitutes—or makes up—the person. Yet, interestingly, constitutionalists insist that persons are not the same thing as their bodies. To see this, consider the different ways that a single dollar coin can be instantiated and the kinds of events it can survive. If the coin were thrown into a hot fire and left for a sufficient amount of time, it would eventually melt, and the dollar would be ruined. And as constitutionalists would point out, the metal of the coin would survive in a different form, but the dollar would be lost. The metal that constitutes the dollar is such that it is able to survive the fire, but the dollar constituted by the metal is such that it cannot survive the fire. If the metal and the dollar have different properties—one has the property of being able to survive a fire and the other has the property of not being able to survive the fire—then the metal and the dollar are not the same thing. Similarly, constitutionalists argue against immaterial souls and claim that human persons are constituted by their physical bodies even if they are not the same thing as their bodies.
One additional observation is worth making about constitutionalism: there are two types of constitutionalism, type I and type II. Type-I constitutionalism, maintained by Corcoran, affirms that human persons have to be constituted by the specific bodies that they have. In other words, Dew has a particular body, and he must have the body that he has. Likewise, Gould has a particular body, and he must have the body that he has. On type-I constitutionalism, it would not be possible for Dew and Gould to switch bodies. But on type-II materialism, maintained by Lynne Rudder Baker, it is not necessary that we each have the specific bodies that we have. All that is required is that we each have some body or another. She says, “I find the traditional thought experiments about bodily transfer—for example the Prince and the Cobbler—utterly convincing when considered from a first-person point of view.”19 So then, while constitutionalists agree that human persons are constituted by their bodies, even if they are not identical to them, they differ over which body is necessary for a person to be thereby constituted.
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So what shall we make of materialism in general? On the positive side, materialists have been helpful in forcing us to see the significance of the body as it relates to human persons. Our brains and bodies have much to do with who we are, what we are like, and what we do. Moreover, philosophers over the past several centuries have generally felt that materialism has a significant advantage over dualism in accounting for mind-body interaction. While dualism struggles to explain how it is that an immaterial mind interacts with material bodies, since they never touch and therefore cannot transfer energy one to another, materialism seems to have no such difficulty. Material seems to enjoy a parsimony and elegance of explanation that gives it a significant advantage over dualism. Yet philosophers have also noticed that materialism is not without problems of its own. In particular, while it might have a better explanation of mind-body interaction than does dualism, it seems to have great difficulty accounting for consciousness in general and qualia in particular. Thomas Nagel puts the problem rather bluntly: “Consciousness is the most conspicuous obstacle to a comprehensive naturalism that relies only on the resources of physical science. The existence of consciousness seems to imply that the physical description of the universe, in spite of its richness and explanatory power, is only part of the truth, and that the natural order is far less austere than it would be if physics and chemistry accounted for everything.”20 Dualists are well aware of this difficulty and often make use of consciousness to critique materialism and to make arguments in favor of substance dualism.
Hylomorphism
In earlier sections of this chapter we discussed the various categories of views that philosophers put forward regarding human persons. Substance dualists tend to make two distinct claims: (1) for “stuff distinction,” the view that there are two radically distinct kinds of things, or two distinct substances, and (2) for “person-soul identity,” the view that the person is a soul who has a body. By contrast, materialists and physicalists reject the immaterial soul and argue that (1) there is only one substance, which is physical, and that (2) human persons are identical to or are at least constituted by their human body. In this last section, we shall briefly describe one final category put forward by Aristotle and Thomas Aquinas, a theory known as hylomorphism.
Hylomorphism is sometimes regarded as a version of dualism and sometimes as a version of materialism. In contrast to the substance dualists who argue for two distinct substances, hylomorphists argue that there is but one substance: a human person. In contrast to materialists, however, hylomorphists argue that the one substance (human person) has two distinct causes: material and formal. The word “hylomorphism” comes from two Greek words: hylē (matter or, more literally, wood) and morphē (form). In the case of the human person, which is a substance, the person is constituted by the material body and the soul, which is the form (life principle or organizing and structuring agent) of the body.
There are at least two important things to notice about this account. First, it understands the concept of substances as it relates to human persons differently than both substance dualists and materialists. For substance dualists, a human body and a human soul are two distinct substances. Hylomorphists reject that notion and instead argue that there is only one substance: just the human person. For materialists there may be only one substance (the human body), and souls do not exist. Hylomorphists agree that there is only one substance but reject the idea that the substance is just the physical body. On this view, the substance of a human person is composed of both body and soul. Second, and flowing out of the first observation, hylomorphists contend for an ontological unity within the person. In other words, hylomorphists reject the substance dualist’s idea of “person-soul identity” described above, which says that persons are their souls and that they have bodies. In his discussion regarding human sensation, for example, Aquinas says, “Since, then, sensation is an operation of man, but not proper to him, it is clear that man is not a soul only, but something composed of soul and body.”21 According to hylomorphism, human persons are both body and soul essentially.
Philosophers and theologians vary on their opinions of hylomorphism. Those who embrace it think that it allows for a unified understanding of human nature while also affirming the biblical categories of body and soul. Critics, however, are more skeptical about the view being helpful, contending that it collapses back down into either materialism or substance dualism. As with dualism and materialism, the debates continue.22
Conclusion
In this chapter we have offered a survey of various discussions surrounding the philosophical debates about human nature. It began with an overview of the basic terms and concepts involved in the discussion and then summarized a variety of positions. It has been our aim to offer a survey only, leaving our readers to decide for themselves. We shall see some of these issues again in other chapters, and especially in chapter 15 as we take a look at the possibility of life after death. For now, let us simply note that various Christian thinkers have defended materialism, substance dualism, and hylomorphism. For our part, we are inclined to think that minds and bodies are distinct kinds of things and that human beings are composed of both. As such, we are inclined to hold some form of either substance dualism or hylomorphism.
1. See, e.g., J. P. Moreland and Scott B. Rae, Body and Soul: Human Nature and the Crisis in Ethics (Downers Grove, IL: InterVarsity, 2000); and Richard Swinburne, Mind, Brain, and Free Will (Oxford: Oxford University Press, 2013).
2. See David Robb, “Substances,” in The Routledge Companion to Metaphysics, ed. Robin Le Poidevin et al. (New York: Routledge, 2012), 256–64.
3. See René Descartes, Meditations on First Philosophy, trans. Donald A. Cress, 4th ed. (Indianapolis: Hackett, 1993). See especially meditation 2.
4. See Aristotle, De Anima 11.1, trans. Hugh Lawson-Tancred (New York: Penguin, 1986), 157.
5. Lynne Rudder Baker, Persons and Bodies: A Constitution View (Cambridge: Cambridge University Press, 2000), 92.
6. Lynne Rudder Baker, “When Does a Person Begin?,” in Social Philosophy and Policy 22 (2005): 28.
7. Moreland and Rae, Body and Soul, 121.
8. Stewart Goetz, “Substance Dualism,” in In Search of the Soul: Four Views of the Mind-Body Problem, ed. Joel B. Green and Stuart L. Palmer (Downers Grove, IL: InterVarsity, 2005), 33.
9. John Searle, The Mystery of Consciousness (New York: New York Review of Books, 1997), 136.
10. Searle, Mystery of Consciousness, 136.
11. Princess Elisabeth of Bohemia, “Elisabeth to Descartes—10 June 1643,” in The Correspondence between Princess Elisabeth of Bohemia and René Descartes, ed. and trans. Lisa Shapiro (Chicago: University of Chicago Press, 2007), 68.
12. John Locke, An Essay Concerning Human Understanding (Oxford: Clarendon, 1975), 2.27.10 (emphasis added).
13. Pete Mandik, This Is Philosophy of Mind: An Introduction (Malden, MA: Wiley-Blackwell, 2014), 140.
14. Nancey Murphy, “Nonreductive Physicalism: Philosophical Issues,” in Whatever Happened to the Soul?, ed. Warren S. Brown, Nancey Murphy, and H. Newton Malony (Minneapolis: Fortress, 1998), 130–31.
15. Murphy, “Nonreductive Physicalism,” 131.
16. Nancey Murphy and Warren S. Brown, Did My Neurons Make Me Do It? (New York: Oxford University Press, 2007), 62.
17. Murphy and Brown, Did My Neurons Make Me Do It?, 63.
18. Kevin Corcoran, Rethinking Human Nature (Grand Rapids: Baker Academic, 2006), 65–66.
19. Baker, Persons and Bodies, 141. Given that Baker identifies the human person and the being with a first-person perspective, it is not surprising that she finds the Prince and Cobbler thought experiment convincing. Such is certainly consistent with her view.
20. Thomas Nagel, Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False (New York: Oxford University Press, 2012), 35. Notice here that Nagel mentions this problem with specific application toward naturalism. To be clear, naturalism is not exactly the same thing as materialism or physicalism. Materialism and physicalism are generally used synonymously and interchangeably to refer to views suggesting that only material or physical objects are included in our ontological discussion. Neither materialism nor physicalism, however, assume a particular view of God. Nevertheless naturalism assumes materialism and physicalism and goes a step farther by rejecting theism and embracing atheism. Yet if consciousness is a problem for naturalism, it is also a problem for materialism and physicalism.
21. Thomas Aquinas, Summa Theologica, trans. Fathers of the English Dominican Province (Notre Dame, IN: Christian Classics, 1947), 1.75.4.
22. For those who defend a substance dualist view of human persons, see examples such as John Cooper, Body, Soul and Life Everlasting (Grand Rapids: Eerdmans, 1989); and Moreland and Rae, Body and Soul. For examples of those who defend materialism’s compatibility with Christianity, see Trenton Merricks, “How to Live Forever without Saving Your Soul: Physicalism and Immortality,” in Soul, Body, and Survival: Essays on the Metaphysics of Human Persons, ed. Kevin Corcoran (Ithaca, NY: Cornell University Press, 2001), 183–200; Peter van Inwagen, “A Materialist Ontology of the Human Person,” in Persons: Human and Divine, ed. Peter van Inwagen and Dean Zimmerman (Oxford: Oxford University Press, 2007), 199–215; and Nancey Murphy, Bodies and Souls, or Spirited Bodies? (New York: Cambridge University Press, 2006).