There are many arguments against dualism. Many of these arguments fall under a broader belief known as monism, which states that instead of two separate substances, the mind and body are part of one substance.
Monism in a Nutshell
- Idealistic Monism (also known as Idealism): The only substance that exists is the mental substance (consciousness).
- Materialistic Monism (also known as Physicalism): The physical world is the only reality, and anything mental stems from the physical.
- Neutral Monism: There exists one substance that is neither physical nor mental, but is where physical and mental attributes come from.
Argument from Brain Damage
This argument against dualism questions how the theory works when, for example, brain damage from trauma to the head, pathological diseases, or drug abuse leads to a compromised mental ability. If the mental and the material truly were separate from one another, the mental should be unaffected by such events. In fact, scientists have discovered that there is most likely a causal relationship between the mind and the brain, and that by manipulating or damaging the brain, mental states are affected.
The argument of causal interaction questions how something immaterial (the mental) has the ability to affect the material. It is still very unclear where such interactions would occur. If you were to burn your finger, for example, a chain of events would unfold. First, the skin is burned; then nerve endings become stimulated. Eventually, the peripheral nerves lead to a specific part of the brain, and the result is the feeling of pain. However, if dualism were true, pain would not be able to be located in a particular spot. However, the pain is located in a particular spot, the finger.
Additionally, the theory of causal interaction deals with how an interaction occurs between the mental and the physical. Let’s say you move your arm up and down. To do so, you first have the intention to move your arm up and down (the mental event). The message travels via neurons, and then you move your arm up and down. However, the mental event of intending to move your arm is not enough to move your arm. There must be a force that makes the neurons send the message. Dualism lacks the explanation of how a nonphysical event can create a physical event.
Argument from Simplicity
Perhaps the most common argument against dualism is also the simplest. The argument from simplicity ponders why someone would attempt to explain the existence of the mind and body in two parts when doing so in one part is simpler.
This is expressed through the principle known as “Occam’s razor,” which states that, when explaining a phenomenon, one shouldn’t multiply entities beyond what is necessary. Therefore, it should be rational for humans to want the simplest explanation.
While parts of dualism have their strengths, there is no denying that dualism does not answer all of the questions that arise from the mind-body problem.