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the constructive study of ontological dualism:
My own understanding about the nature of the soul and how I can show that it exists has been greatly aided by Christian philosopher J.P. Moreland and Christian theologian Jonathan Edwards. Their extensive influence will be evident throughout what follows, especially since one of my major aims is to set forth the case that Moreland makes for the existence of the soul in a book he co-authored with Gary Habermas called Beyond Death: Exploring the Evidence for Immortality.
As should be clear from the title, the main aim of the book is to provide evidence for immortality. They focus on three lines of evidence: the existence of the soul, the resurrection of Jesus, and near-death experiences. Of course, these things are themselves hotly contested, and so in order to establish their case they must extensively defend the reality of each of these three things.
I strongly recommend the excellent evidence for Jesus' resurrection set forth in chapters five and six, and refer any interested party who cannot obtain a copy of the book to my article The Resurrection of Christ: Myth or Reality, which is based upon the approach and evidence given in these chapters. I also strongly recommend the section on near-death experiences for those interested in whether there is any good evidence for them and how to understand the evidence from within a traditional and solid Christian theology. And it goes without saying from the existence of this paper that I also strongly recommend the section of Moreland and Habermas's book on the existence and nature of the soul (though there are points where we differ, such as on the nature of freedom).
As has been said, the purpose of Moreland and Habermas in discussing the soul is to provide evidence for life after death. Their argument is pretty simple:
Unlike Moreland and Habermas, however, my current aim is not to give evidence for life after death. My aim is to explore the nature of the soul. But this requires another task first - answering the question of how we can know that we have a soul.
It seems to me that we can best understand what a soul is if we first examine the arguments for its existence. This may seem backwards-for how can you know if something exists if you don't know very clearly what it is? But I think that this will actually bring about the greatest clarity. For as we examine the arguments for the soul's existence we will progressively come to understand more about its nature. By demonstrating the existence of the soul, the nature of the soul will of necessity be unfolded.
The result is that when it comes time to examine the nature of the soul, we will not be interacting with new concepts but putting together in a systematic whole the concepts that were already unfolded in the defense of the existence of the soul. Additionally, when the pieces are finally put together as to what the soul specifically is, it will have greater significance to us because we will see why it must be the case that the soul is the way it is.
The Existence of the Soul
There are some who deny the existence of the soul. This view is called physicalism because it upholds that we are purely and only physical beings. In contrast, dualism holds that we are not merely physical but, in addition to being physical, we also have a non-physical aspect of our being. Dualists differ among themselves on the nature of the soul. The two main views are property dualism and substance dualism.
There are significant differences among these views, and so they must be clearly understood if we are going to argue for the Christian understanding of the soul. And in order to understand these differences, we must understand certain key terms.
A substance is an independent entity, such as an apple. Moreland helps clarify this definition by pointing out five characteristics of a substance.
First, a substance is an individual entity. It is not a quality that can exist in many places at once, but is a self-contained entity, distinct form all other entities of its nature, and so can only be in one place at a time.
Second, a substance is continuous entity-which means it remains the same through change. For example, "a leaf can go from green to red, yet the leaf itself is the same entity before, during, and after the change" (41).
Third, a substance is a fundamental existent. This means, in other words, that "they are not in other things or had by other things" (41). For example, an apple has the property of redness but is not the same thing as redness. This is why I defined a substance above as an independent entity. What I mean is that it does not depend upon something else (other than God) for its existence. It can exist "by itself."
Fourth, a substance is a unity of "parts, properties, and capacities." Moreland gives the example of his dog, which has the property of brownness, parts such as legs and teeth, and capacities such as barking. "As a substance," he writes," Fido is a unity of all the properties, parts, and capacities had by him."
Fifth and finally, "a substance has casual powers. It can do things in the world. A dog can bark; a leaf can hit the ground" (41, emphasis added).
A property is an attribute of a substance, examples of which are triangularity and hardness. Moreland helps clarify the nature of a property by pointing out several characteristics and contrasting it with substance.
First, a property is not an independent entity but must be in an something else (namely, a substance). For example, one cannot find redness existing all by itself. It is always found in something, such as an apple. So whereas a substance is a fundamental existent and has other things but is not in other things, a property does not have other things but is in other things. One must ask of a property "what is it that has that property," but it would be nonsense to ask that of a substance. As Moreland writes concisely, "Substances have properties; properties are had by substances" (42).
Second, a property is a universal. This means that it can be many places at once because it "can be in more than one thing at the same time." In contrast, a substance can only be in one place at a time because it cannot be in anything.
Third, properties posses immutability. This means that, unlike substances, they cannot maintain their identity through change. If they were to change, they would loose their identity. For example, "when a leaf goes from green to red, the leaf [which is a substance] changes by losing an old property and gaining a new one. But the property of redness does not change and become the property of greenness. Properties can come and go, but they do not change in their internal constitution or nature" (42).
Last of all there are events, which are "states or changes of states of substances. An event is the coming or going of a property in a substance at a particular time, or the continued possession of a property by a substance throughout a time" (42). The change of a leaf from green to gold in the fall is an example of an event. The leaf is the substance, the colors are properties, and the change of the substance from the possession of one property to another (i.e., green to gold) is an event.
With these key terms understood, we can now understand the nuances of physicalism, property dualism, and substance dualism.
Is the Soul a Myth, a Substance, or a Property?
Physicalism: The soul is a myth
As we saw above, physicalism teaches that humans do not have souls (which are non-physical aspects of a being), but are purely physical. But what about our experiences of thinking, pain, and emotion? For these things seem to be mental entities and thus non-physical. How are those explained on the physicalist view?
According to physicalism, thinking, emotion, pain, etc. are simply physical properties and physical events of the physical substance of our brain and central nervous system. So what seem to be mental (and thus non-physical) entities are actually physical entities. Which means that "the neurophysilogist can, in principle, describe these events solely in terms of C-fibers, neurons, and the chemical and physical properties of the brain. For the physicalist, I am merely a functioning brain and central nervous system enclosed in a physical body. I am a material substance, a creature made of matter-nothing more, nothing less" (43).
As evidence for physicalism, it is often pointed out that for every so-called mental event, a corresponding change in brain activity can be demonstrated. From this it follows, it is said, that physical and mental events are the same-that is, what appear to be mental entities are simply physical entities (that is, physical properties, events, and substances)--and thus dualism is false.
But this does not follow. Surely if dualism is true there is a connection between brain (the physical organ in our heads) activity and mental activity (the activity of our souls). But connection is not identity. As Moreland writes, "...just because A causes B (or vice versa), or just because A and B are constantly correlated with each other, that does not mean that A is identical to B" (48).
So the correlation between brain activity and mental events can be easily accounted for by recognizing that the mental and physical interact with one another and so influence one another. Thus, what happens in the physical brain influences and is reflected in the non-physical soul; likewise, what happens in the non-physical soul influences and is reflected in the physical brain.
Property dualism: The soul is a non-physical property of a physical substance
In contrast to physicalism, property dualists acknowledge that human beings are both body and soul. However, unlike substance dualists, property dualists hold that the soul is not a mental substance, but merely a set of mental properties and events of our brain-a physical (not mental) substance. In other words, property dualism acknowledges that we have physical substances, properties, and events. And it acknowledges that we have mental (non-physical) properties and events. But it denies that we have a mental substance. Our mental properties simply adhere over our brain (physical substance) the way wetness adheres over water.
This view, then, goes a step further than physicalism but a step short of substance dualism. The result is a very different understanding of the nature of the soul. For if there is no such thing as a mental substance, then our soul is not a spiritual entity that has our thoughts and stands behind them. Rather, the soul is simply the set of mental properties and events of the physical brain and not an independent substance.
According to property dualism, then, the soul is not an entity in its own right, but a collection of events and properties. From this it follows that I am "not a mental self that has my thoughts and experiences. Rather, I am a brain and a series or bundle of successive experiences themselves" (46).
Furthermore, property dualism must hold that the existence of our soul (that is, the collection of our mental properties and states) is dependant upon our body. For our soul is simply the collection of mental properties and events of the body. The implication of this is that there could not be life beyond death because when our bodies die, our souls must also die.
Substance dualism: The soul is a non-physical substance
In contrast, substance dualism holds that the soul is a mental substance-not merely a set of mental properties and events of the physical brain, but an independent mental entity in its own right. As Moreland writes, "...the brain is a physical substance that has physical properties [and events], and the mind or soul is a mental substance that has mental properties [and events]." As a result, "the soul is the possessor of its experiences. It stands behind, over, and above them and remains the same throughout my life. The soul and the brain can interact with each other, but they are different substances with different properties" (46).
Arguments for Dualism in General
We are now in a position to better understand what is meant when the issue is raised of whether we have a soul. In short, the issue comes down to this: Which is true - physicalism, property dualism, or substance dualism? It will not do to simply show that physicalism is false, for that will not establish whether the soul is a substance or property. And if that is not established, then the existence of the soul will not be established because, I would argue, a soul that is merely a collection of mental properties and events is not a soul at all.
Moreland does an excellent job establishing the case for substance dualism, and so what follows is mainly a summary of his arguments. Following Moreland, we will first examine the arguments for dualism in general. These arguments do not show which form of dualism is true, but they do establish that physicalism is false. Second, we will then be in a position to examine the arguments which establish the truth of substance dualism over property dualism.
The Law of Identity
To make his case for dualism, Moreland first points out what is called "Leibniz's Law of the Indiscernibility of Identicals," which says that if something is true of A that is not true of B, then A and B are not the same thing. For example, if A is round but B is square then they must be different things; if A and B were the same thing, they would both have to be round (or both would have to be square).
That is simple enough. But what this means is that if it can be shown that there are things that are of us that cannot be true of a purely physical entity (that is, a physical substance, property, or event), then it will be established that we are not merely physical. Which means that dualism will be established, for dualism is the belief that there is both the physical and something that is non-physical (the mind) to our being.
In other words, physicalists claim that the mind is simply a physical entity-namely, a physical property and/or event of a physical brain. Dualists claim that the mind is a truly mental (i.e., non-physical) entity. So if it can be shown that there are things true of our mind that cannot be true of any physical entity, then it will follow that our mind is not physical-that is, it will follow that we have a soul.
Mental events differ from physical events
This is Moreland's first main argument in support of dualism. Briefly stated, he points out that mental events do not have the same features as physical events. Therefore, mental events are not physical, but are truly (not just apparently) "mental" and non-physical.
For example, a mental event would be a feeling of pain, an episode of thought, or our self-awareness. A Physical event would be "the happenings in the brain and central nervous system that can be described exhaustively using terms from chemistry and physics" (49). But it is evident that physical events lack features that mental events must have. Mental events such as "thoughts, feelings of pain, or sensory experiences do not have any weight; they are not located anywhere in space...On the other hand, the brain events associated with my thoughts, etc.-indeed, with material things in general-do have these features" (49).
To illustrate this, Moreland suggest picturing a pink elephant in your mind. If one were to open up your brain, he could not find a pink elephant. You would be having a sensory experience of a pink elephant, but no picture of a pink elephant could be found by examining your physical brain. Thus, the sensory event of imagining a pink elephant cannot be a physical event of the brain, because it "has a property-pink-that no brain event has" (49).
Mental events are self-presenting; physical events are not
Next, Moreland argues that mental properties are self-presenting. This means that the individual having them (1) has private access to them and (2) knows them incorrigibly. I have private access to my feeling of pain-nobody else is feeling the sensation I have when I am pricked with a pin. Likewise, I know such a sensation incorrigibly, which means I cannot be wrong about it. Whether or not there really is a pin sticking me, I know with certainty if I feel pain in my arm. Even though I can be wrong about whether a pin is really sticking me, I cannot be deluded about the fact that I am feeling pain. For I only know that I am feeling pain by actually feeling pain.
Physical states and properties, however, are not self-presenting. That which is physical is always "public domain." We only have private access and incorrigibility about mental states and properties. Therefore, "physical states/properties are not identical to mental states/properties" (51). Which means, in other words, that mental states and properties are non-physical.
Conscious experience cannot be explained in purely physical terms
Conscious experience and awareness of sensations appear impossible to explain in purely physical terms. As Moreland writes, "The subjective texture of our conscious mental experiences-the feeling of pain, the experience of sound, the awareness of color-is different from anything that is simply physical" (52).
Take, for example, the sensation of pain-a mental event. Can it be that it just seems to be a mental event and is really a physical event or property? It seems that the answer must be no because sensations have as their very essence "the felt quality or sensory property that makes them what they are" (44).
But a felt quality has no physical features. This is evident from the illustration Moreland gives about a deaf scientist who becomes an expert on the neurology of hearing. He might be able to know everything about the physical process of hearing, but there is still one thing he would not know: what it is like to hear something. Since the felt quality of something-that is, the experience of what it is like--is the essence of a sensation, it follows that a sensation is not physical. Thus, there is a dimension to hearing (and all sensations) that is beyond the physical. And if there is something beyond what is purely physical, then dualism is by definition true.
Moreland writes, "Secondary qualities are qualities such as colors, tastes, sounds, smells, and textures. Primary qualities are qualities that are thought to be among the properties that characterize matter-weight, shape, size, solidity, motion. Physicalism seems to imply that secondary qualities do not exist in the external world. For example, we are led to believe that color is really nothing but a wavelength of light" (52).
We do, however, know that secondary qualities exist because we experience them. Red is not merely a wavelength of light; there is "sensory quality" of a color that we experience when we our eyes encounter something giving off a certain wavelength of light. But how could this be if physicalism is true?
A physical object can have many relationships to another physical object. It can be close or far, above or below, larger or smaller than. But it is nonsense to think of a physical object as having a purpose or aim towards something. It would be nonsense to think of a collection of atoms intending to do something. So it does not seem that a physical entity can have the property of intentionality. Intentionality could only exist if there is something more than the physical realm.
Arguments for Substance Dualism in Particular
These several arguments and many others seem to make a solid case against physicalism. But they do not settle the debate about what the soul actually is. Is the soul a mental property of a physical substance, or a mental substance in its own right? In other words, what is right-substance dualism or property dualism?
Moreland's first argument for substance dualism is from our intuitive awareness of ourselves. Remember that according to property dualism, there is no mental self that has your series of mental events and properties. Instead, the brain, which is not itself conscious (since it is a purely physical substance) has a series of conscious experiences of things such as pain and sound, and these experiences are themselves the soul. As Moreland writes, "If I simultaneously experience a sound and a pain, the mental 'self' is just the bundle of conjunction of the experiences themselves. If I 'experience' them successively, then the mental 'self' is just a series of separate, discrete mental events/experiences that come and go and replace one another through time...." This must be because, according to property dualism, "There is no mental substance that stands under them as their possessor" (54-55).
But it is evident upon self-reflection that we are not identical to the mental experiences that we have. There is something that stands behind those experiences and has those experiences. In fact, our ability to reflect upon ourselves presupposes substance dualism, because a set of events that come and go can do no reflecting. Additionally, it is evident upon self-reflection that I am more than my body-which is also evident from the arguments that we have seen against physicalism. Thus, there must be some sort of non-physical substance (that is, a mental substance) that has a mental life and indwells a body. I cannot be the collection of experiences that my brain has. Rather, I must be a mental entity that stands behind those things and has them.
Continuity of identity through change
Property dualism not only contradicts our intuitive awareness of self, but also destroys continuity of identity. For it teaches that the self is a bundle of mental experiences. But that means that as the experiences change, we change for we are those experiences!
But if continuity of identity is false, then so also is personal responsibility. For the reason a criminal is responsible for the crime he committed last week is because he is the same person who did it. If he is not the same person who did it, then it would be wrong for our government to send him to jail for it. Since personal responsibility for what we did in the past is true (as evidenced by the fact that God will judge everyone according to their deeds and that our consciences accuse us for what we have done wrong in the past), it follows that property dualism must be false and substance dualism must be true.
A property dualist might respond that his view does not destroy continuity of identity because the "stream of successive selves [is] held together by resemblance between each self in the stream-similarity of memory or brain, similarity of character traits, and/or spatial continuity" (59).
However, similarity cannot constitute identity. For example, Moreland writes that "memory presupposes personal identity; it does not constitute it." Imagine the case where all of your memories were transferred to a friend, and all of his memories were transferred to your mind. Would that mean that you are now your friend? Clearly it would not. There must be something to have those memories for them to be memories. And if there is something that has memories, the memories might change but the person remains the same.
Second, memory cannot constitute identity because one can loose all of their memories and remain the same person. Those who have suffered extreme amnesia are examples of this. Would we dare say that they are no longer the same person? If they weren't, then they could not be held accountable for the sins they committed before they lost their memory.
Third, "I seem to be aware of the fact that I am literally the same self that continues to exist throughout my life that unites my stream of consciousness into one stream that is mine. How can a physicalist or property dualist explain this basic awareness?" (59).
So it seems evident that our souls do possess a continuity of identity through change. And this means that the soul cannot be merely a mental property of a physical substance because properties do not remain the same through change. Only substances remain the same through change; therefore, the soul must be a substance.
Finally, if someone were to admit that the soul is an actual substance, not merely collection of properties and events, but is a physical substance, I respond that the arguments we saw in the previous section have shown physicalism to be false. Thus, since it has been shown that our souls are substances, not merely events or properties, then it follows that they must be non-physical substances.
The Scriptural teaching
The Bible teaches substance dualism in many places. For example, in describing the way Benjamin was named, Genesis 35:18 says, "And it came about as her [Rachel's] soul was departing (for she died), that she named him Ben-oni; but his father called him Benjamin." Notice two things. First, the text explicitly mentions the existence of the soul. Second, the soul cannot be simply a way of referring to her body or even the properties of her body because it is said to have been departing. Is the text saying that Rachel's body was departing? Of course not. Her body stayed right where it was and became lifeless. Likewise, the soul in this text cannot be merely mental properties of the body because such things would cease with the death of the body, not depart. Only a substance could depart.
Philippians 1:23 is another clear verse. Speaking of death, Paul says that he has "the desire to depart and be with Christ, for that is very much better; yet to remain on the flesh is more necessary for your sake." If Paul did not have a soul, he could not "be with Christ" when his body died. He would be unconscious and in the ground. Likewise, if the soul was simply a property of the body Paul could not say he would go to be with Christ at death, for when his body died his soul would cease if it was simply the properties of his body.
These three arguments are convincing to me. I believe that we have souls simply because the Bible teaches it, but understanding the other arguments for its existence helps one set forth a more informed case for the soul's existence when challenged. But, most importantly, it helps us understand the nature of the soul better, as we will see more clearly soon. First, however, there are several significant implications from what we have seen that I would like to bring out.
It is interesting to realize that, since substance dualism has been shown to be true, it follows that evolution must be false. For evolution has no mechanism for allowing the development of a non-physical soul. Indeed, if evolution is true, then everything can be explained in purely physical terms and there is no place for a non-physical realm. Therefore, since physicalism is false, it follows that evolution must be false as well. For evolution cannot account for a non-physical realm of living existence.
Of course, some evolutionists might believe in God and say that He intervened supernaturally at times, and one of those times was to create a soul. But this position is inconsistent because it is not supported by either science or the Bible. One can point to no scientific evidence that God did this. And one cannot point to any biblical evidence, either. So this position has no ground to stand on. It is simply a strange way of trying to reconcile two contradictory views of how the world came to be.
Do animals have souls?
I have wondered about this for a long time, and when I learned the basic concepts above I finally realized the answer. The answer is yes, they do. They must have souls because there are aspects of their being that cannot be explained in merely physical terms. They make decisions, they express emotion, they can see, they can hear, they can smell. A purely physical entity cannot do those things-it can only act like it can. Thus, animals must have a non-physical substance as part of their beings just as humans do.
What are angels and demons?
I've believed that angels and demons exist as long as I can remember. But I've always had a hard time conceiving of what they are-that is, what they "consist of." Are they simply non-physical in the way thinking is? Or are they simply "spiritual forces"? They answer must be no. Angels and demons are non-physical, that is for sure. They are purely non-physical-unlike us, they have no bodies. But, like the non-physical aspect of our being, they are substances. Angels and demons are non-physical substances. They are not simply spiritual forces that have personhood. They are spiritual substances.
The Nature of the Soul
But the usefulness of the arguments we saw is not simply in pointing to the reality of the soul and the helpful implications that this has. The arguments we examined have also unfolded for us some of the most significant things about the nature of the soul. As we now place these pieces into a more systematic whole, we will be able to see why we understand the soul the way that we do and be in a better place to comprehend exactly what the soul is.
Definition of the soul
The basic elements of what the soul is have already been presented and expounded upon. Therefore, we can set forth this summary definition of the soul without having to re-define all of the words: The soul is a mental and invisible substance "standing beyond and under my mental properties as their possessor and unifier" which is aware of itself and its experiences and which makes me a conscious and living being (54). We will now briefly unpack this definition.
The soul is non-physical
This has been highlighted and demonstrated throughout what has gone before. It is hard to say exactly what the soul is made of. But it is easy to say what it is not: it is not material. We can perhaps best understand what the soul consists of by understanding what it is not.
It should be pointed out, however, that this difficulty is not unique to the immaterial world. It is in fact more difficult to define what matter is. But it is easy to give examples: The air in the room, the cement on the sidewalk, the hand on a person are all examples of matter. If we ask what matter is like, we can simply point to those objects and say it is like them even if we can't give a precise definition of what it is made of. Likewise, if we ask what something non-physical is like, we can understand that it is mostly not like the physical things we experience and point to examples.
Because the soul is non-physical, we can better relate to God because God is non-physical. But because we are physical in addition to spiritual, we can more fully express the glory of God and our love for God than if we were only spiritual. We should not fall into the gnostic error of depreciating the physical world.
The soul is a non-physical substance
While the soul is non-physical, it is nonetheless a substance. And this means at least five things. First, it is an individual entity. There is only one property of redness no matter how many different places red exists in the universe; but each instance of a soul is distinct from all the other instances of a soul.
Second, the soul remains the same through change. Your mood can change, memories can change, or beliefs can change. But your soul remains the same. And therefore you have continuity of identity.
Third, the soul is a unity. While it has different faculties and capacities, it cannot be divided. Our bodies can be split in half and remain a body-though seriously wounded. But a soul cannot be split in half. It makes no sense to think of a "half person" or of one soul divided up into two people.
Fourth, the soul is a fundamental existent. Unlike a property or event, it does not depend upon something else (other than God) for its existence. It exists in its own right and has properties and events.
Fifth, the soul can do things. It can will and bring things about because it has casual powers.
With these five things in mind, we see that though the soul is not physical it is still possible to understand what it means to say it is a "substance." The soul is a non-physical entity that is a distinct thing which remains the same through change, is unified, is fundamental in its existence, and is capable of bringing things about.
The soul contains our center of consciousness
The soul, however, is not some lifeless substance. It is lively and animating. And so it is conscious. It is self-aware and able to understand reality and experience what it is like. But since it is a substance, this means that it is not a collection of conscious experiences or properties; it is a center of consciousness that has those collective experiences. As such, it is "what I am cognizant of when I engage in various acts of introspection in which I am aware of what is going on 'inside' me."
The soul is not dependant upon the body
Since the soul is a substance, it is a fundamental existent. Which means that its existence is not dependent upon the body. As Moreland has said, the soul "...has a foothold in being independent of its embodiment, even though embodiment bay be the soul's natural mode of existence" (383, n. 8). What this means is that our soul does not simply pass out of existence because our body dies. Rather, it is possible that it lives on apart from the body. And we know that this is actually the case from the word of God, which teaches that upon death the soul's of believers go to be with the Lord, and the soul's of unbelievers go to hell to be punished and excluded from His presence.
While our souls are capable of existing apart from our bodies, that is nonetheless not the natural mode of our existence. God created us as unified beings-both body and soul joined together as one person. Therefore, God will resurrect the bodies of all people on the last day, and we will enter into our final destination of the lake of fire or the new heavens and new earth on the basis of whether we are in Christ or not.
The body is not simply a physical object
This is one of the most fascinating things that follows from the fact that God created us as a unity of body and soul. As Moreland writes, "It should be pointed out that the body of a living organism, e.g., the human body, is not simply a physical object, because the soul diffuses throughout the body and makes it a distinctively and irreducibly human body while it is ensouled" (383, n. 16).
The soul is equally present at all parts of the body
But what exactly is the relationship between body and soul? It is evident that our souls are somehow "in" our bodies. But where are they in our bodies? In our brain? Moreland explains:
...the soul is in fact fully present throughout the body and completely 'in' each part of the body. But the 'in' is not a spatial concept. Water is spatially 'in' a glass. However, even though my thoughts are 'in' my mind, my mind is not a container like a bucket with thoughts spatially inside it. It makes no sense to ask if my thought of lunch is closer to my left ear than to my right one! In the same way, my soul is 'in' my body in some sense, but my body is not a spatial container for my soul. If you cut off my hand, you do not cut off part of my soul (25).
Perhaps the "omnipresence" of the soul in the body explains why when your arm is pricked you feel the sensation in your arm and not in your brain-which is where the stimuli is actually processed in your physical being.
The soul interacts with the body
One of the biggest objections to substance dualism is that, if soul and body were fundamentally different things, then they could not interact with one another. How can two things that are completely different from one another have a cause and effect relationship? Doesn't there have to be some common ground in order for their to be interaction? As Moreland states it, "How could a soul, totally lacking in any physical properties, cause things to happen to the body or vice versa?" (86).
Moreland points out several things in response. First, even if we do not know how A causes B (for example, how the soul causes the body to move) it does not follow that it is irrational to believe that A causes B. There are several instances of causation where we do not know how the interaction takes place. For example, exactly how can protons "exert a repulsive force on each other?" (87).
So the main question is whether A and B interact even if we cannot understand how. Surely there is more to reality than we currently grasp! "In the case of mind and body," writes Moreland, "we are constantly aware of causation between them. Episodes in the body or brain (being stuck with a pin, having a head injury) can cause things in the soul (a feeling of pain, los of memory)...We have such overwhelming evidence that causal interaction takes place, there is no sufficient reason to doubt it" (87).
The existence of God is one excellent reason to believe that it is possible for the spiritual and physical to interact, for God (who is spiritual) created (that is, caused to be) the universe which is both spiritual and physical.
Second, however, Moreland points out that
Third and finally, it seems to me that just because the mental and physical are different does not mean that they have nothing in common. There is a common ground existing between them by virtue of the fact that they are both of God, and by this common ground they are able to interact.
The soul has two faculties
What we have seen so far helps unpack and explain what the soul is, but insight into the dynamics of the soul comes from understanding its faculties. A faculty is a "compartment" of similar capacities, or abilities. Moreland holds that there are several faculties of the soul. I, however, find it more compelling to agree with Jonathan Edwards that there are only two faculties of the soul: understanding and will.
According to Edwards, then, the soul has two faculties: understanding and will. By the understanding we perceive and comprehend things; by the will we choose. The will, further, has two ways it can exercise itself. It can either be inclined to approve of what the understanding apprehends, or it can be inclined to disapprove of what the understanding apprehends.
But how do our affections fit in? Are they the result of some third faculty? No. The affections, according to Edwards, do not differ in kind from our acts of will. Rather, they differ only in degree. The affections "are no other, than the more vigorous and sensible [i.e., felt] exercises of the inclination and will of the soul."
I found the following quote from Edwards so helpful in this area that I am simply going to quote it at length:
This understanding of the faculties of the soul is important because it helps us understand better what the soul is. It is one thing to know that it is a substance. But our understanding of it is greatly enhanced when we see what it is capable of doing and the "mechanics" of it, so to speak. Additionally, Edward's understanding of the understanding and will (and affections) has immense implications for other subjects that we will not go into now, such as Christian hedonism, the nature of freedom, and worship.
States of the soul
Finally, it is helpful to understand that the soul can be in different states. A state of the soul is simply the way in which the faculties are being exercised. When we our understanding is engaging in thought, we are in a thinking state. When we are paying attention to what our eyes see, we are in a seeing state. When we perceive pain or pleasure, we are in a feeling state. Obviously we can be in several states at once, though one state is usually predominant over the others.
There is so much more that could be said, but we need to stop here. These things greatly help me understand better who I am and how I relate to the world and God. But they raise many unanswered questions in my mind as well. For example, it is unclear to me what the difference is between person and soul. I don't think we can identify the soul as our persons because that would seem to deny that our bodies are part of our persons and would have, it seems, unorthodox implications regarding the doctrine of the Trinity. The doctrine of the Trinity is, in short, that God is one substance but three persons. But if person and soul are the same thing, it would seem that person and substance are the same thing-which would mean that God is both one substance and three substances.
Consequently, I don't think that we can identify the soul as our person. But we can at least say that our soul is part of our person and where our seat of personhood is located. Perhaps it is possible for soul and person to be the same while at the same time avoiding the unorthodox implications. But, for now at last, that is an unanswered question of mine.
Regardless of the unanswered questions I have, I am very grateful to God for giving me a more adequate understanding of the soul. It is important to understand what we are.