When making a case for Christianity I usually focus on the scientific and historical lines of evidence. However, I’ve learned there are also philosophical evidences relating to human mind and consciousness. These arguments potentially undercut some important naturalistic assumptions relating to the human mind and the brain.
I’ve noticed when conversing with the sceptic they often tacitly accept they have a mind and are free to engage it by exploring arguments for the Christian worldview. So, I’ll investigate their tacit assumptions about mind and identify these as part of the cumulative evidential case for Christianity.
It seems to me that I can discuss four areas with the sceptic; first, I’d introduce substance dualism as proposed by the Christian worldview, second the evidences for substance dualism, third the common inadequate naturalistic explanations for mind and fourth I’d conclude by proposing a reason substance dualism points to a creator.
I’ll lay that case out in this blog.
Introducing Substance Dualism
Substance dualism claims the human mind is separate but has a causal relationship with the brain; while the brain is, “subject to the laws of physics; mental states are subject to the laws of logic.” (1) It denies people are determined, proposing instead that we all have free will.
Alternative naturalistic explanations of mind demand everything must have an explanation that is “inside the room.” (2) This understands the human mind as equivalent to the physical brain; our thoughts and feelings must therefore be explained by appealing to the deterministic laws of chemistry and physics. This suggests that people are pre-determined to think and act in certain ways as dictated by their physiology.
Yet evidence for substance dualism is found in the context of every debate between the Christian believer and the sceptic. Both parties exercise free will as they debate, and their discussion appeals to the laws of logic as they construct and respond to the arguments for and against Christianity. Therefore, the debate itself provides evidence for the Christian understanding of mind. Persons freely exercise their will, and are therefore not subject to the deterministic physical processes that would determine them under an equivalent brain and mind.
Arguments Supporting Substance Dualism
Having introduced substance dualism, I’d go on to strengthen the case by showing that mind and brain are different and therefore not equivalent. Mind cannot be explained in purely naturalistic terms. I’ll appeal to the following lines of evidence.
First, the physical brain is public while the contents of the mind are wholly private. The brain is public in the sense that a surgeon may open a patient’s skull, expose their brain tissue and operate on it. In that sense, brain is available to anyone who needs access to it. By contrast, the human mind is private. No-one can understand the contents of another person’s consciousness apart from that particular conscious person. Even psychologists cannot completely describe the contents of their patients mind; they only know what the patient has chosen to reveal. The rest of their mind is private to the patient. The public brain therefore does not share characteristics with the private mind; they are essentially different and cannot be the same.
Second, mental states have intentionality while physical entities do not. My mind operates from intentionality when it formulates a case against Christianity; I intend to present a case. However, the brain does not. It is physically located in one’s skull, it objectively exists, but cannot exhibit intentionality. The mind is different from the brain.
Third, while one can be incorrect about a physical entity, a mental state is always indisputable. I may incorrectly assume that a red chair is physically located in the next room, but I cannot be mistaken that I have a belief about that physical object in my mind; my belief is indisputable.
Fourth, while material objects are described objectively, the mind operates in the realm of subjective opinion. If material naturalism were true, then everything in nature could be fully described using objective terms alone. This is not the case, however, because subject opinion exists in the universe. My subjective opinion will often be shared during a debate about Christianity. But my opinion on whether or not Jesus was a real person, for example, is not physically located somewhere inside my skull. The “personal, subjective nature of mental states distinguishes them from anything physical.” (3)
Fifth, while a physical object like a brain can be measured and weighed, mental states cannot. While physical objects are evaluated by reference to physical laws, mental states are evaluated by reference to the logical laws; they cannot be measured or weighed.
Inadequate Naturalistic Explanations of Mind
In my discussion with the sceptic, I’d discuss the inadequacy of naturalistic explanation for mind. For example, sometimes mental states are described as human behaviour, therefore maintaining a naturalistic explanation for mind. Yet we intuitively know that our thoughts are the cause of our physical behaviour, not the other way round. (4) So this naturalistic approach fails to explain mind.
The group called the “eliminating materialists” simply dismiss mental states, saying they are nonexistent. However, their assertion is self contradictory. I’ve stated in my case for substance dualism that mind uniquely reflects the property of intentionality. It is this property that the materialist must explain, yet they do so by appealing to an intention. Their explanation therefore fails because they cannot dismiss intentionality by exercising it. (5)
Brain injury impairs the activity of mind, and some point to this as evidence of equivalence. Rather than equate brain with mind, it may suggest a firm causal relationship between the two substances.
In summary, naturalistic explanations of mind do not work; they are self-contradictory and deficient, and they attempt to dispense with the mental states they cannot explain. (6)
Why Substance Dualism May Point to God
If people’s mental lives have a separate causal relationship with their physical existence, then this aligns with and supports the Christian understanding of God. While God is spirit, he also took physical form in the incarnated Jesus. It seems reasonable to infer therefore that God’s nature would be reflected in people; “in the image of God he created them.” (7)
 J. Warner Wallace, God’s Crime Scene: A Cold-Case Detective Examines the Evidence for a Divinely Created Universe, (David Cook), 132.
 Wallace, 130.
 Wallace, 128.
 Wallace, 132.
 Wallace, 134.
 Wallace, 135-137.
 Genesis 1:27.