Key Takeaways
- Dualism holds that the mind and body are separate, with mental experiences not fully explained by physical processes alone.
- René Descartes popularized dualism by arguing the mind is non-physical while the body and brain are physical.
- Modern neuroscience challenges dualism by showing strong links between brain activity, chemicals, and consciousness.
Dualism is a philosophical concept that concludes that the mind is separate from the body, and that therefore, mental phenomena are not physical in nature and vice versa. It can trace its roots to ancient Greece and philosophers like Plato and Aristotle, who grappled with the relationship between the mind and the body, as well as early Hindu philosophy.
What Is Dualism?
Dualism is a philosophical concept that states that the mind and the body are separate.
If you’re familiar with the gut-brain axis, you’re likely aware of the growing body of scientific research around the idea of the mind-body connection. We continue to learn more about how factors such as gut health, diet, and physical health are connected to mental health.
Dualism represents a more abstract, philosophical approach to this concept, but it demonstrates how we have been grappling with the idea of the mind-body connection for ages.
While various schools of thought have emerged over the centuries, the clearest articulation of a dualistic view was proposed in the 17th century by philosopher René Descartes. Descartes argued that the mind and body are separate, with the mind being the non-physical seat of consciousness and the brain being the “physical seat of intelligence.”
Understanding the Different Types of Dualism
There are several kinds of dualism. Here are some of the most popular.
Substance Dualism
Substance dualism, also known as Cartesian dualism, argues that the mind and the body are fundamentally different. According to Dr. Brian Tierney, a licensed psychologist, “This type of dualism considers that the mind and the body are composed of… different substances”—an immaterial mind that has mental properties and a material body that has physical properties.
René Descartes was a key proponent of this view. He believed that the mind and the body could exist independently of one another, but that the body could not think without the mind. This kind of dualism is compatible with many theologies that claim that people’s immortal souls are in a different plane of existence from the physical plane.
Substance dualism has four main theories championed by different philosophers:
- Interactionism holds that material causes produce mental effects. The opposite is also true. Descartes believed, incorrectly, that the pineal gland was the reason for the interaction between the mind and body.
- Occasionalism says that the basis of the interaction between the material and immaterial cannot be material. Instead, each instance of these individual interactions is caused by God. The 17th-century French philosopher Nicholas Malebranche was a proponent of this kind of dualism.
- Parallelism, championed by Age of Reason German philosopher and mathematician Gottfried Leibniz, states that while mental causes only have mental effects and physical causes only have physical effects, God makes it seem as if mental and physical events are caused by one another.
- Epiphenomenalism asserts that physical causes can cause either physical events or mental events, but mental causes can’t cause anything because they’re just the product of physical causes that occur in the brain. Thomas Henry Huxley came up with epiphenomenalism in the 19th century, which he based on Thomas Hobbes’ materialist theories.
Property Dualism
Property dualism, in contrast to substance dualism, “suggests that there are mental and physical properties of the same substance, such as the activity of nerves in the brain,” says Tierney. That is, while the mind has non-physical properties, they emerge from the brain, a physical substance.
“For example,” Tierney explains, “the sensation of pain has physical properties involving actual brain activity, as well as mental properties that have to do with the subjective experience of, say, stubbing your toe.”
Epistemological Dualism
Epistemological dualism deals with the nature of knowledge, according to Tierney. This has to do with whether the world we see and experience is actually the real world or, in fact, merely a copy generated by the brain’s neural processes. Tierney says that philosopher Immanuel Kant explores this in his work.
This has also been used to distinguish knowledge from belief, reason from faith, and facts from values. Knowledge, reason, and facts are objective, while belief, faith, and values are subjective.
What Are the Arguments for Dualism?
There are several arguments for dualism, including:
The Mind-Body Problem
The mind-body problem asks what the relationship between the mind and the body is. This has been addressed in various ways by different thinkers. For example, according to Daniel Boscaljon, PhD, director of research and co-founder of the Institute for Trauma Informed Relationships, for one branch of philosophers, “the mind’s theoretically unlimited potential is contrasted favorably with the body’s susceptibility to time and space.”
Tierney explains, “The way the mind-body problem is articulated supports dualism because it suggests that mental and physical properties are fundamentally different.” That is, the mind and body stand in contrast as two separate systems.
The Problem of Consciousness
Known as the “hard problem” of physics, the problem of consciousness observes that conscious states and physical states are not the same thing.
As Boscaljon says, “This often gets to the chicken and egg problem.” Some believe consciousness came first, while others believe matter or the physical came first. Either way, this serves as an argument for dualism as it posits consciousness or the mind as distinct from the body.
The Argument From Personal Identity
This argument, which dates to the late 1700s, holds that a person’s identity is distinct from their physical body. “In the identity debates,” observes Tierney, “it is hard to find thinkers who argue that every aspect of the identity is physical.” This supports dualism and tends to lead to another kind of dualism: nature versus nurture.
What Are the Arguments Against Dualism?
Criticisms of dualism include the following.
The Interaction Problem
Proponents of this criticism tell us that, as Boscaljon says, “it wouldn’t make sense for there to be two qualitatively different substances”—i.e., the mental and the physical.
Instead, Tierney explains, “physical pain, for example, can interact with the mind and the mind can create physical pain in the body over time… If the mind and the body interact like this,” they can’t be separate the way dualists claim.
The Problem of Causal Closure
Causal closure states that every physical event is determined by a physical cause. This idea comes from materialist physics and holds that while a physical object can be put upon by outside forces, there is no need for a non-physical explanation.
As a result, scientists who believe in this argue against dualism. According to Tierney, “this approach can be found in various regions of psychiatry, where behavior is about neurons and observable molecules, not the mind.”
The Argument From Neuroscience
This criticism stems from neuroscience’s discovery of “tight correlations between the functioning of the mind and the functioning of the physical brain.”
Tierney takes this one step further, saying, “Beyond correlations are the neuroscientific findings that regions of the brain such as the thalamus can be directly stimulated to create changes in consciousness.”
“Additionally,” Tierney continues, “chemical messengers like serotonin can have a dramatic effect on consciousness, as experienced when taking serotonin modulators such as magic mushrooms or LSD.” Neuroscience is, thus, a strong voice against dualism.
How Dualism Appears in Different Fields
Dualism shows up in a variety of fields. Here are three:
- Philosophy of Mind: This is a very broad field that often champions dualism. “Most people interested in philosophy of the mind likely reject the importance of material reality,” says Boscaljon, “especially those trained in Anglo-American philosophy or newer schools of consciousness studies that ascribe to…the belief that everything reduces to the mind.” Much of what we’ve reviewed in this article comes from philosophy of the mind.
- Religion and Spirituality: Many contemporary schools of religion or spirituality embrace dualism, particularly the separation of the soul or spirit (instead of the mind) and the body. As Boscaljon observes, while these schools view the soul as infinite, the body is finite, fallen, and weak. This is the core of many religious beliefs about the immortal soul and the afterlife.
- Psychology and Cognitive Science: Branches of psychology and cognitive science that subscribe to dualism typically study mental processes that cannot be fully explained by physical processes alone. For instance, Tierney cites subjective experiences and consciousness as two processes that can’t be understood by studying the brain alone.
Understanding Contemporary Views on Dualism
The following represent some of the more modern perspectives and arguments around the idea of dualism:
- Dualism vs. Monism: While dualism separates the mind and body, monism takes the approach that everything has a single substance or cause—that, as Boscaljon says, it is all mind or all matter. Generally, Tierney observes, monists hold that the physical is the cause of everything.
- Dualism and Materialism: Materialism, unlike dualism, proposes “that everything is material or physical, including the mind,” says Tierney. Materialism, according to Boscaljon, defines itself in terms of quantifiable elements, ignoring everything else.
- Dualism and Emergentism: Emergentism, says Boscaljon, suggests that “things can be more than the sum of their parts.” Tierney furthers this argument, saying, “In the context of mind-body, emergentism suggests that mental states are emergent properties of the brain. In the context of the universe, some emergentists argue that consciousness is an emergent property of matter.”
