The Mind-Body Problem


By Steve Humphrey


The relationship between the mind and body has been recognized as a philosophical puzzle since Rene Descartes, a 17th Century French Rationalist whose most famous contribution to Philosophy is the quote “I think, therefore I am.” The mystery can be stated thusly. We as humans are constituted out of  two distinct elements. We have a physical body, made of oh too solid esh, and we have a non-physical mind, the “Ghost in the Machine,” as it were. The two are essentially related. When we prick our skin, we feel pain. When we walk through a garden, we smell flowers. When we exert our will, we can make our bodies do things, like picking flowers. But how does this happen? The body and the mind are entirely different entities. The body is physical and corporeal, and the reason is insubstantial and non-corporeal. How do my delicate and ephemeral thoughts cause my fleshy fingers to type the words you are now reading? 

It was discovered later that the seat of the conscious mind lies within the brain. At one time, we thought that the brain served to cool the blood, which would explain fevers. Only in the modern era did we realize that our brains consist of nerve cells, axons and neurons among them, along which electrochemical signals pass, connecting different parts of the brain in very complex ways. However, these are purely physical processes. Neurons and axons are not conscious, nor do they contain images and feelings. We call this the “The Hard Problem” in Philosophy of Mind and Neuroscience. No matter how well we think we understand the brain, we have no way of explaining our conscious experiences, our “inner life.” No form of accounting for the experience of smelling a rose, the glory of a sunset, the thrill of a tender caress, the taste of a pineapple, or the sound of Janis Joplin singing “Me and Bobby McGee.” Nothing in our brains smells like a rose or feels like a kiss. Even if we had a complete dictionary connecting every mental event with some neurological processes, we still could not say we understood how our mental life came to be.

Philosophers have tried two different tacks. “Reductionism” is the view that mental events can be “reduced” to or defined in terms of brain events. The anti-reductionists are appalled and insulted by the idea that complex psychological states can reduce to brain states. An alternative view is called “Supervenience,” a made-up word that means that mental properties cannot exist without physical properties. It is associated with the concept of “emergentism.” Specific higher-level properties emerge out of more fundamental properties as a result of size and complexity. The atoms in our bodies are not alive, but we are, and it is hard to say just where in the scaling up life begins. Consciousness is not like pregnancy; things can be more or less conscious. My cat Olivia is certainly more aware than an earthworm, but a bit less than me (presumably, but with cats, you never know).

Some, including Descartes, think that the mind is a spiritual substance, a soul, made up of the same stuff as God. But this doesn’t solve the problem. How does the soul affect the physical body? Descartes thought the causal process occurred in the pineal gland, but locating it doesn’t explain it. Another view is Pre-Established Harmony. God has created body and mind, and they work in harmony, without any causal interaction. God just set it up that way. 

Neurophysiological work in the last few decades has only deepened the mystery. By studying people who have suffered lesions or injuries to their brains, we teased apart some of the details of the process. There is a phenomenon known as “blindsight,” in which people who have suffered a particular brain trauma become blind. They can’t see a thing. But when asked to point to some object in front of them, a task they regard as ridiculous, they most often point correctly. It turns out that the optic nerves connect to several different parts of the brain. Presumably, the information captured by the retina bypasses the conscious part but is transmitted to some regions involved in pointing. This sort of thing is not limited to the blind. Our sensory apparati are constantly bombarded by stimuli. If we were conscious of all of it, we would be overwhelmed. The brain filters out most sensory stimuli, and only salient features are transmitted to consciousness. It isn’t magic or ESP if you have ever experienced déjà vu or the sudden realization that someone is watching you. It is just your brain alerting your consciousness to some piece of information that you had but of which you were not consciously aware. (Google “selective attention test” and watch the video.)

A further mystery. Since the 1990s, neuroscientists have had access to fMRI (functional MRI) machines, which can see which areas of the brain are active in real-time. The fMRI allows researchers to observe what parts of the brain work when specific actions are performed. When instructed by the experimenter to lift an arm, the brain responsible for moving the arm becomes active a fraction of a second before that part of the brain which is involved in the conscious will. That is, it would seem as if moving the arm comes before willing the arm to move. So, what role is your conscious will playing?

Due to Sir Roger Penrose, one theory proposes that consciousness at its root is a quantum phenomenon. I call this the “Multiplication of Mysteries.” We don’t understand consciousness, and we don’t understand quantum mechanics; maybe they are related. (Eventually, I will write a column or two on quantum mechanics. See if I don’t!)

One scary conclusion from all this, which I am sympathetic to, is that we are simply meat machines, and consciousness evolved only to allow us to passively watch what is going on. Consciousness is a bystander to what is an enormously complex physical process. Consider zombies. In Philosophy, as opposed to on TV, a zombie behaves just like the rest of us but has no inner life. If the brain is doing all the work, perhaps consciousness is unnecessary, a lagniappe. And if you think about it, how do you know that anyone other than yourself experiences consciousness? You might be the only sentient creature in a world of zombies.

Steve Humphrey has a Ph.D. in the history and philosophy of science, with a specialty in the philosophy of physics. Questions? Comments? Suggestions? 

Email him at steve@thevoicelouisville.com.