Louise Malan | 7 October 2021 | 7 min read
Christian scholar, J. Gresham Machen, said: “I think we ought to hold not only that man has a soul, but that it is important that he should know that he has a soul.” What a person believes has real-life implications, therefore Christians should believe the truth. Typically, two fundamentally different accounts of the mind are given, the physicalist material account and the dualist account. This article makes an indirect case for dualism, by showing that the physicalist account is unreasonable.
Physicalism is the position that humans are exclusively physical things—there is no non-physical dimension to the self. Dualism states that humans are not merely the combination of physical parts, but that they have an immaterial part too. In some contexts, distinctions can be made between the soul, the spirit, the ego, the self, etc., but this work will group all those terms as indicating an immaterial aspect of the self, which will collectively be called “the soul.” This term can be even better understood as a non-material substance which contains consciousness and animates the body.
Physicalism can be split into reductive and non-reductive physicalism. The former maintains that mental states are identical (and reducible) to brain states. The mind does not really exist, only the brain does. Non-reductive physicalism maintains that while mental states are not reducible to brain states, the soul does not exist. Mental states depend on the brain for their existence. The mind supervenes on the brain. An example of this kind of supervenience is the wetness of water. Water is made up of hydrogen and oxygen. Neither hydrogen nor oxygen are wet at room temperature, but when they are combined in a certain way, they produce water, which has a property of being wet. The property of wetness supervenes upon the water. In a similar fashion, the mind supervenes upon the brain. “Any causal powers of the water are not due to the supervenient properties. The causal powers are due to the underlying base properties of the oxygen and the hydrogen to cause and bring about certain things. Similarly, the causal properties of the brain are its physical properties, not its mental properties.”
Now, there are phenomena that are widely agreed upon to be real, but physicalism fails to account for them. If physicalism were true, one would not expect these phenomena to exist. So, if you think that they do exist, then it is unreasonable to hold that physicalism is true. The more plausible view will be that the soul exists, and by extension some form of dualism must be accepted.
Reductive physicalism fails to account for our mental lives. The brain only has physical properties, such as volume, colour, mass, location, and so on. It is not the brain that becomes excited or angry, it is the mind. “When your back hurts and you are in pain, it is not the brain that is in pain, even though the brain is involved in the neural circuitry that gives you the experience of pain.” One cannot reduce pain to the physical brain state, even though there is neural activity correlated to it; the brain state is not literally identical to the mental state. Thus, reductive physicalism fails.
Non-reductive (and reductive) physicalism fails to account for free will, mental causation, and reasoning.
Free will is not possible on physicalism. Physicalism entails determinism, because each event is caused by a prior event, and will cause a consecutive event. So, there is a chain of events that is governed by the laws of nature and is fixed. Thus, there can be no free choosing to do, or not to do. Interestingly, if all events are predetermined, that means mental events are predetermined. This would mean that beliefs can never be reasonable; we never have reasons for our beliefs, we only have causes. There is no option of believing something else if it is more reasonable, you can only believe what you are predestined to believe. This view undermines itself, because its proponents try to convince you that it is reasonable to believe in a system that implies that you can never be reasonable. If your cognitive faculties lead you to believe that your cognitive faculties are unreliable, why would you trust that belief in the first place? The view is self-defeating. Free will is also necessary for moral responsibility, and it is self-evident that moral responsibility is real, so free will must also be. If you believe that you ever do anything freely, and that people are responsible for their actions, then you should believe in the existence of a soul. Therefore, to affirm physicalism is to affirm a view that is both self-defeating and undermines that which is necessary for moral responsibility.
If mental states simply supervene on brain states, they have no causal power. This means that they cannot bring about anything. But it is quite intuitive to think that you cause your arm to be raised by thinking about it. Mental causation is further discussed in part 2 of “Do Souls Exist?”
Reasoning is impossible if we are only our brains. Physicalism undermines the necessary preconditions for rationality. If someone were to say that there are good reasons to believe physicalism, but physicalism does not allow you to reason at all, this would be self-refuting. At least four things are necessary for reasoning to be possible:
- A conscious self that is united at a time
- A conscious self that is united over time
With regards to a unified self at one time, imagine a line of reasoning as follows:
A = B
B = C
Therefore A = C.
The two beliefs (A = B, B = C) must be united in one consciousness at the same time in order to reason to A = C. But the brain processes information in parallel. Daniel Dennett, an atheist cognitive scientist writes: “there is no one place in the brain through which all these causal trains must pass in order to deposit their content.” A soul, however, can account for a unified self at a time because the soul is simple (not composed of parts). In addition, thoughts seem to be the belongings of the soul and here more than one thought can be had at the same time. This gives us then a conscious self that is able to hold both premises in her mind, united, at once.
The self must also be united over time. This is because reasoning takes time. One needs to exist long enough to draw a conclusion. For example: Jack believes A = B and B = C, and then he goes out of existence. Jill did not believe the premises Jack did, but believes A = C. Neither of them reasoned to the conclusion that A = C. In order to reason, one must exist long enough to believe the premises and conclusion. These mental states hold the propositions, and on physicalism, are caused by corresponding brain states. But the brain is not united at any given moment in time, so it cannot be united over moments of time. Furthermore, the brain is in a constant state of flux. No state remains the same for more than a moment. There is no single enduring brain state that is always present. It simply moves from one brain state to the next. The brain is not literally identical to itself at any two moments. On this view, the self is like the flame of a candle. The candle and the wick endure, but the flame does not endure from one moment to the next. There is a type of continuity because the candle does not go out while it is burning, but there is a different flame at each moment. Alex Rosenberg, a naturalistic philosopher, says that there is no enduring self on atheism. He affirms: “The self […] is a fiction. It doesn’t exist.” In other words, I do not exist. This begs the question as to who made this statement. But to bring it back to the example, if Jack is not the same thing at time T1, when reasons are recognised, as at time T2, when conclusions are drawn, then he did not reason to the conclusion. In contrast, the soul can explain this because it is both a simple substance (not composed of parts) and remains the same in essence over time; thoughts may change, but the soul remains the thinking subject. So, the soul is a conscious self that is united over time.
In addition, subjectivity is required to reason. What does this mean? In order to reason to the conclusion, Jack must interpret the content of his beliefs and (mentally) see that it follows from the premises. In contrast, computers do not interpret their output or see what it means. A subject is needed for that. Although a computer makes transitions in accordance with reason, it is not reasoning. It is merely following the rules of logic programmed into it. It does not see that anything follows because it lacks subjectivity. According to physicalism, our brains simply are “meat computers” and all our states and transitions can be thought of in impersonal terms. But simply going from one brain state that contains certain information, to a brain state that contains other information, does not constitute reasoning. For example, a scientist could detect that you held beliefs A = B and B = C in your mind, but you are sleepy and do not think about the conclusion, then the scientist inserts the thought A = C into your mind. You have not reasoned to it, although your transition is the same as that of someone who reasoned to the conclusion. A soul can account for reasoning because it is a subject and can interpret its thoughts and see what follows from them—it has subjectivity.
Moreover, intentionality is required for reasoning. Thoughts have a particular “aboutness” to them. They refer to something outside of themselves. In other words, thoughts contain content which the thought is about. Having this property is called having intentionality. On the other hand, physical objects do not have this property. “The brain is not about something any more than a chair […] is about something.” Books or paintings may contain markings on a page or canvas, but only once someone reads or interprets it is there a thought which is about something. Now, there is a difference between working with syntax/symbols and truly understanding the meaning via intentionality. It is one thing to connect relevant symbols to one another. It is another thing entirely to understand the meaning of these symbols. This is illustrated by John Searle’s Chinese Room argument. Imagine an individual who only speaks English who is in a room with a box of Chinese writing characters he cannot understand, and a book of instructions which he can (partially). The book of instructions says: if sequence x of characters comes in, then output sequence y of characters. Then a native Chinese speaker relays a written message of Chinese characters by sliding the message under the door. The person in the room receives the note, and returns a note according to his instructions. He does not understand the meaning of the messages. He is simply an input-output machine. He is connecting all the relevant symbols in order to create the right output given a certain input. The native Chinese speaker thinks the person in the room can speak Chinese though, because the returned message has this appearance. Now, if someone had to reason out our example of A = C, they would have to understand the content, not simply match patterns according to a set of rules as a computer does. For to reason is to interpret some input in order to intentionally arrive at the correct output. But if physicalism were true, then we would have no intentionality. There is nothing that implies an “aboutness” as part of physical components or electrical signals, which the brain can be reduced to. Much like a computer, input is fed in which is translated into electrical signals. The input means nothing to this kind of physical thing. Any output a computer makes according to its rules is to be interpreted by subjects, who are the ones who actually understand it. On physicalism, the human does not understand any input, but merely reacts according to rules to arrive at an output. There is no reasoning process here. So, on physicalism, intentionality is an illusion. Rosenberg bites the bullet and says we never truly think about anything. This, again, begs the question whether I can think about Rosenberg’s statement. This view, however, is flawed. An illusion is always an illusion of something, which implies intentionality. Therefore, the view that intentionality is only an illusion is self-refuting. In contrast, the soul intrinsically has intentional mental states. When persons think about something, they truly are thinking about that thing, and this is made possible by the soul. Thus, the soul grants the intentionality necessary for reasoning. If you think that you ever have thoughts about anything, then you ought to believe in the reality of the soul.
In conclusion, reductive physicalism fails because it cannot account for our mental lives. Non-reductive physicalism fails because it cannot account for free will, mental causation, and reasoning. Since these phenomena are clearly real and incompatible with physicalism, one ought to reject physicalism. So, if physicalism is false, it must be the case that the self is not exclusively composed of physical parts. The existence of the soul is clearly the more plausible view, and by extension some form of dualism must be accepted.
The opinions and views expressed in this article are those of the author and do not necessarily reflect the views and opinions of the employees and members of Ratio Christi South Africa.
 J. Grescham Machen, The Christian View of Man (New York: The Macmillan Company), 159.
 “Doctrine of Man – Part 10: Refuting Reductive and Non-Reductive Physicalism,” available at https://www.youtube.com/watch?v=04UqtJafWCA&t=1461s, accessed August 20, 2021.
 Menuge A, In Defence of the Soul (Denmark: Dansk Bibel-Institut).
 Daniel Dennett & P. Weiner, Consciousness Explained (New York: Little, Brown and Company), 135.
 A. Rosenberg, The Atheist’s Guide to Reality (New York: W.W. Norton & Company), 217.
 Menuge, In Defense of the Soul.
 “Doctrine of Man – Part 10: Refuting Reductive and Non-Reductive Physicalism”
 Rosenberg, The Atheist’s Guide to Reality, 214.