Interactionism: Mind-Body Relationship


The mind-body problem is a philosophical debate concerning the relationship between the mind and the body. Throughout history, philosophers developed a number of theories arguing whether the human mind and body are fundamentally different or share the same nature, and, if so, what their nature is. Some claim that minds and brains are essentially the same and are both physical in their nature, whereas others believe that the mind is a spiritual entity that leaves the body when a person dies. The two traditional and competing theories are dualism and materialism, both comprising several branches of thought. In this essay, the Cartesian theory of dualism is discussed.

Main body

Cartesian dualism, or interactionism, was developed by the 17th-century French philosopher Rene Descartes. Some elements of his theory have precedents in the works of earlier thinkers, Aristotelianism, and Stoicism, and are featured in many Asian philosophies (Heil 29). Interactionism is based on the idea of the independent existence of two separate realities: the physical realm and the spiritual world. In the physical realm, science is the dominant authority, while the spiritual realm is governed by religion (Lawhead 75). Physical bodies, like stars, operate independently of spiritual entities, such as angels.

The dual nature of the universe also implies the dual nature of human beings. Descartes believes that humans are a union of mind and body, which are separate substances, closely joined together. The mind is a non-physical and, therefore, non-spatial entity, whereas the body and the brain are physical entities. The mind is capable of consciousness and self-awareness, whereas the brain is simply the seat of intelligence. The body is characterized by the physical presence but not by thought and feeling, whereas the mind has no spatial extension but can think and feel.

The main point of interactionism that distinguishes it from other dualist theories is the idea of the interaction between the mind and the body. Descartes claims that the mind and the brain, being closely connected to each other, can interact and influence one another (Lawhead 72). Mental events can cause bodily events, and physical events can cause mental events. This assumption can be easily proved by an individual’s everyday experience. For example, when a person sees something that frightens them, they experience a feeling of fear, which is non-material and reacts to it accordingly, running away, hiding, or attacking the aggressor. In this way, the physical world influences an individual’s sensory experience of it, and they react to this experience behaviorally.

Descartes argues that the interaction between the mind and the body occurs in the pineal gland of the brain, where the soul is located, and all thoughts are formed. At that time, the knowledge of the brain was limited—the scientists knew about the pineal gland but did not know its function. Descartes used the newly discovered organ to assume that it serves as a mediator between the body and the mind (Lawhead 75). He described the functioning of the pineal gland through the idea of “animal spirits” that stimulate the nerves producing sensory stimuli and causing sensory perception. In this way, the soul alters the motions in the brain, which then affect the body.

From the conventional point of view, interactionism seems to be one of the most plausible theories explaining human sensory experience in a way that aligns with common-sense beliefs. People experience the physical world in a non-physical way, and their feelings, thoughts, and emotions are not governed by the laws of physics. Cartesian dualism greatly influenced later mind-body theories and provided a foundation for modern psychology and a number of philosophical doctrines. However, the theory has also been criticized for not sufficiently elaborating on the connection between the mind and the body, and some crucial contradictions.

The primary argument against Cartesian dualism concerns the question of how exactly the mind and the body connect if they are so different from one another. The interaction of physical entities involves physical forces and can be explained by the laws of physics. Mental entities can also engage with each other through the exchange of ideas and emotions. The principle of causality states that there must be a likeliness in essence between cause and effect (Heil 30). If the mind is not a physical thing, it cannot affect the body through gravitational, magnetic, or mechanical forces, and the relations between them cannot be explained using the brain because it is also a physical entity.

Descartes’ theory of interaction occurring in the pineal gland is misguided and does not solve the problem because the gland is merely another material object within the body. If a part of the brain interacts with the mind, it is still unclear how this interaction takes place. The nature of “animal spirits” mentioned by Descartes is unknown, and regardless of whether they are physical or spiritual forces, it is still unclear how the physical can affect the mental.

Interactionism is also criticized for the assumption that the pineal gland is the principal place of the soul, which creates a contradiction within Descartes’ theory. If the mind is a non-spatial entity, it cannot occupy any particular physical space inside a human body. However, the interaction between the mind and the body needs to take place somewhere. Neither Descartes nor his followers were able to provide a satisfactory explanation on the matter.

Another critical argument against Cartesian dualism is the question of whether the mind can exist outside the body. Descartes claims that, as they are separate entities, the mental can function outside of the physical. Within his theory, he offers two types of explanation: religious and scientific (Heil 30). According to the religious explanation, the possibility of the mind existing outside the body, especially after a person’s death, provides a sufficient foundation for religious beliefs and a rational basis for the hope of an afterlife. According to scientific theory, the separate existence of the body and the mind explains the complete absence of mentality from physical entities, such as stones, trees, lakes, and other objects of nature. Neither religious nor scientific explanation is supported by sufficient arguments.


Cartesian dualism is one of the most plausible theories explaining the mind-body problem. It acknowledges the everyday human experience and attempts to explain it from a theoretical perspective. Descartes, the author of the concept, claims that the mind and the body are two separate entities that are closely connected and influence each other. Mental processes can affect human behavior, and the events of the physical reality shape a person’s perception of it. However, the theory does not provide any detailed explanation of how the interaction between the mind and the body takes place, and the arguments that Descartes used in his works, now seem to be outdated.


Heil, John. Philosophy of Mind: A Contemporary Introduction. Routledge, 2013.

Lawhead, William. The Philosophical Journey: An Interactive Approach (6th ed.). McGraw-Hill Education, 2013.

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