Has Neuroscience Undermined Warrant For Believing In The Soul?

Today, many believe the findings of neuroscience have undermined the rationality for believing in the soul. But no matter how often that idea is verbalized, nothing could be further from the truth. Why? Because if the soul is an immaterial substance containing consciousness (sensations, emotions, thoughts, beliefs, desires, acts of free will) and also animates the body and gives it life, then the methods and findings of neuroscience are almost entirely irrelevant to questions about the nature and existence of consciousness and the soul.

Different fields of study—art, psychology, logic, physics, ethics, history, philosophy, neuroscience—employ varied methods to study different objects, yet they provide knowledge of their appropriate subject matter. For example, the methods of logic and math vary from those employed in chemistry, and logic and math are used to study different objects than those investigated in a laboratory. Branches of human knowledge, then, have their limits; they are set by other branches of knowledge. Specifically, the limits of science in general, and neuroscience in particular, make them inadequate to elucidate the nature and existence of consciousness and the soul. These matters are objects of theological and philosophical knowledge, not of neuroscience.

To illustrate, consider the notion of empirically equivalent theories. When two theories are consistent with the same empirical data, they are empirically equivalent. Take, for example, Neo-Darwinism versus Punctuated Equilibrium Theory (the view that physical objects retain their size over time versus the notion that the size of objects doubles hourly as does the size of our measuring instruments). In such a case, empirical, scientific considerations cannot be used to adjudicate between the rivals. Instead, more philosophical considerations like simplicity and explanatory power must be considered.

Now, consider three theories about consciousness and the self. First, strict physicalism holds that conscious states like pains or thoughts are really nothing but physical states in the brain; moreover, it states that no self exists beyond the brain or body. The human person is entirely physical. Second, property dualism holds that no self exists beyond the brain or body, but conscious states are genuinely and irreducibly mental, not physical states: both are contained in the brain. Third, substance dualism holds that physical states, like certain neurons firing, are in the brain while mental states, like a feeling of pain caused by firing neurons, are in the soul.

These three theories are, strictly speaking, empirically equivalent. For example, consider mirror neurons, which must fire in the right way in order for someone to experience empathy for another. The three empirically equivalent theories account for this: mirror-neuron firing is identical to a feeling of empathy (strict physicalism); mirror neurons are physical states that cause the mental state of feeling empathy, and both states are in the brain (property dualism); mirror neurons are physical states in the brain that cause the mental state of feeling empathy in the soul (substance dualism). Property and substance dualists accept correlations, causal connections, and dependency relations between physical and mental states; for example, brain damage can keep one from recalling memories. Nonetheless, this does not prove they are identical nor does it prove that physical states and mental states occur in the same owner.

After all, if a person is locked into the driver’s seat of a car, he is dependent on the car to move. If the steering wheel is broken, allowing only right turns, this does not prove that the driver is the car, but that while he is in the car, he depends on its functioning parts. Similarly, while in his body, the individual needs certain organs—eyes, ears, and brain—to function properly lest his mental functioning be impeded. Neuroscience can only show correlations, causal relations, or functional dependencies between mental states and physical states, between the self/soul and the brain/body. In the 1200s, Thomas Aquinas said that a damaged brain would limit one’s thinking; neuroscience has only made this observation more precise.

The irrelevance of neuroscience and the centrality of theology and philosophy for clarifying issues of consciousness and the self can be easily seen in the following, typical questions in philosophy of mind that neuroscience cannot answer.

First, they cannot answer ontological questions like these: To what is a mental or physical property identical? To what is a mental or physical event identical? To what is the owner of mental properties/events identical? What is a human person? How are mental properties related to mental events? Are there essences and, if so, what is the essence of a mental event or of a human person? Is a man essentially a human, a person, or both?

Second, they cannot answer epistemological questions like these: How do we obtain knowledge or justified beliefs about other minds and about our own minds? Is there a proper epistemic order to first-person knowledge of one’s own mind and third-person knowledge of other minds? How reliable is first-person introspection, and what is its nature? If reliable, should first-person introspection be limited to providing knowledge about mental states, or should it be extended to include knowledge of one’s ego?

Third, they cannot answer semantic questions like these: What is a meaning? What is a linguistic entity, and how is it related to a meaning? Is thought reducible to or a necessary condition for language use? How do the terms in our common-sense psychological vocabulary get their meaning?

And fourth, they cannot answer methodological questions. How should one proceed in analyzing and resolving the first-order issues that constitute the philosophy of mind? What is the proper order between philosophy and science? Should we adopt some form of philosophical naturalism, set aside so-called first philosophy, and engage topics in the philosophy of mind within a framework of our empirically best-attested theories relevant to those topics? What is the role of thought experiments in the philosophy of mind, and how does the first-person point of view factor into generating the materials for formulating those thought experiments?

Neuroscience is a wonderful field of study, but like other fields, it has limitations.