adimas | Adobe

Searching for the Ghost in the Machine

August 22, 2019

You have probably heard the phrases “mind over matter,” “it’s all in your head,” or “mind and body.” These phrases imply the separation of mind and body/brain. Notions of the mysterious mind being something other than physical or material have existed throughout time.

Some brain scientists have suggested most people are naturally dualist; they believe that the mind is immaterial, nonphysical, and doesn’t have a specific location (doesn’t involve spatial properties), while the body/brain is a physical structure. However, most dualists agree there is interaction, at least at some level, between the nonphysical mind (rational soul, mental) and the physical body. These types of interactions present a puzzling question: How do these interactions occur in a mechanistic, materialistic, physical universe?

Plato, who saw no need for empirical evidence, believed the only reason that we can think about ourselves and our mortal body is that we have an immaterial, immortal soul (Kandel 2006). Aristotle asserted that a nonmaterial psyche was responsible for all human thinking, emotion, and motivation. In Aristotle’s view, the psyche worked through the heart to produce action (Kolb and Whishaw 2009). Mind is an Anglo-Saxon term representing memory; when psyche was translated into English, it became mind. Subsequently, in the thirteenth century when St. Thomas Aquinas incorporated the soul into Christian thought, he and other religious thinkers believed that the soul is divine.

Modern thoughts regarding mind and body separation are heavily influenced by Rene Descartes. Descartes was a French anatomist, mathematician, and philosopher. Almost any textbook, popular writing, or classroom discussion regarding the distinct nature of mind and body involves mention of Descartes. In the seventeenth century, Descartes promoted the idea that humans have a dual nature: they have a body made up of material substance and a mind that originates from the spiritual nature of the soul. Gilbert Ryle, a philosopher of science, in his critique of Cartesian Dualism referred to the soul as “the ghost in the machine.”

Descartes believed animals were different than humans. “Animals were nothing more than intricately crafted machines made up of passive particles” (Zimmer 2004, 36). Humans were different than animals in that they contained a substance independent of matter or physical properties. The mind/rational soul was not influenced by mechanical laws. The mind was capable of things that no machine was capable: consciousness, detailed memory, doubt, and complex understanding. Descartes believed that the soul communicated with the body and that communication occurred through the pineal gland. He identified the pineal gland as the seat of the soul (Kolb and Whishaw 2009; Shorto 2008). He chose this gland as the place where the soul resides following the logic that the pineal gland is the only structure in the brain not comprising two bilaterally symmetrical halves. 

Today we know that the pineal gland is involved with biorhythms and is not in fact a storage site of the soul. When people suffer from pineal gland damage, they don’t lose their minds; in fact, noticeable behavioral or cognitive changes don’t occur. Dualists must address the puzzling question: If the mind and body are completely distinct, how does a physical structure, the pineal gland, transmit immaterial mental energy? Descartes was never able to solve this problem. He even implied that this problem might be too difficult for the human mind to contemplate, noting that “It does not seem to me that the human mind is capable of forming a very distinct conception of both the distinction between the soul and the body and their union; for to do this it is necessary to conceive them as a single thing and at the same time to conceive them as two things; and this is absurd” (quoted in Shorto 2008, 177). Did Descartes give up the dualist approach to mind and body?              

The Biological Mind

Over 2,000 years ago, Hippocrates argued all mental processes emanate from the brain. By the middle of the nineteenth century, the view of materialism was being formed. Materialism asserts that behavior can be explained as a function of the brain, with no need for immaterial mind; the brain is essential for the mind. A series of clinical cases reported in the late nineteenth century showed brain damage to the inferior frontal lobe, in the left hemisphere, was associated with disorders of speech. Paul Broca and Carl Wernicke found speech areas in the brain. When these areas were damaged, language disorders occurred (Kolb and Whishaw 2009). Wernicke provided the first model showing how language is represented in the brain’s left hemisphere. Another strong line of evidence indicating the brain’s role in mental processing is research showing the biological underpinnings of memory. In the latter part of the twentieth century, neurosurgeon William B. Scoville removed the middle parts of the temporal lobes from a patient referred to as H.M. The removal was performed as a treatment for severe epilepsy. The treatment stopped the epilepsy but resulted in severe memory loss. Eric Kandel won the Nobel Prize for his research on the biology of memory.   

One of the most famous neurological patients in history is Phineas Cage. During an explosion, a long iron tampering rod was launched through his head. The rod entered at the left cheek, passed through the eye socket through portions of his frontal lobe and out the top of his skull. After the accident, his memory was the same, but his personality and social skills changed drastically. People who knew him said he was no longer the same person. Case studies involving similar brain injuries show people’s personalities have changed, and they have lost their ability to act in socially acceptable ways. 

Neuroscientist Michael Gazzaniga presents interesting questions to the mind-body dualist: How do you explain personality changes, changes in language production, changes in memory retrieval, changes in consciousness, or any other changes that are results of brain damage (Gazzaniga 2009)? As an extension of Gazzaniga’s line of questioning, consider the following: dementia (cognitive decline) is the result of brain changes, brain plasticity (experiences change brain anatomy) exists, memory strengthening indicates changes in brain structure, and mind altering substances (alcohol, heroin, cocaine, LSD, etc.) induce changes in brain chemistry.

Most brain scientists agree that the mind is rooted in neurobiology. This view rejects the mind/body dualism position (Satel and Lilienfeld 2013). A comprehensive assessment of the mind and its emergent properties involve a brain-based level of analysis but also behavioral and cognitive measures. (Emergent properties are higher-order functions that are derived from complex interactions among lower-order properties; thus, they cannot be reduced to merely lower-order properties. The mind is not fully reducible to the level of neural/brain elements.)      

A comprehensive study of the mind requires neuroscience and psychology. The mind reflects electrical-chemical signals emanating from the brain. The mind is a product of biological systems; it is shaped by interactions involving the brain, body proper (body outside of the brain), and the environment. As Nobel laureate Eric Kandel notes:

Mind and brain are inseparable. The brain is a complex biological organ of great computational capability that constructs our sensory experiences, regulates our thoughts and emotions, and controls our actions. The brain is responsible not only for relatively simple motor behaviors, such as running and eating, but also for complex acts that we consider quintessentially human, such as thinking, speaking, and creating works of art. Looked at from this perspective, mind is a set of operations carried out by the brain, much as walking is a set of operations carried out by the legs, except dramatically more complex.


Gazzaniga, M. 2009. Human: The Science Behind What Makes Us Unique. New York, NY: Harper Collins Publishers. 

Kandel, E. 2006. In Search of Memory: The Emergence of a New Science of Mind. New York, NY: W.W. Norton & Company.

Kolb. B., and I. Whishaw. 2009. Fundamentals of Human Neuropsychology, 6th Edition. New York, NY: Worth Publishers. 

Satel, S., and S. Lilienfeld. 2013. Brainwashed: The Seductive Appeal of Mindless Neuroscience. New York, NY: Basic.

Shorto, R. 2008. Descartes’ Bones: A Skeletal History of the Conflict between Faith and Reason. New York, NY: Vintage Books. 

Zimmer, C. 2004. Soul Made Flesh: The Discovery of the Brain and How It Changed the World. New York, NY: Free Press.