
Descartes’ philosophy is called dualistic, which implies the equality of the material and the ideal but allows the existence of these two phenomena separately from each other. In one of his main theses devoted to the study of the interaction between the mind and body, the philosopher, while comparing bodily and spiritual substances, speaks of their opposition (Thibaut, 2018). Descartes deals with the question of what is true in the content of the mind, in other words, in representations: ideas, affects, and judgments. He speaks of the complete difference between the mind and body, which implies that the body is divisible and the mind is not because the activity of the latter cannot be explained by mechanical principles (Dika, 2020). In his explanations, Descartes offers an adequate solution to the mind-body problem. The argument that the connection of the body and mind is an empirical fact given to a person in everyday experience is logical, and their difference is directly determined in the act of philosophical reflection.
The Problem and Solution
To solve the mind-body problem, Descartes sorts out the content of consciousness in order for clarity and distinctness. In the mind of a thinking subject, in addition to the idea of ​​oneself, there are ideas about inanimate bodies, other living beings, people, and God. According to Dika (2020), the conception of oneself is clear and distinct and, therefore, true. Ideas about other living beings can be formed from available experience. Descartes guarantees the truth of the original principle as clear and distinct knowledge by the existence of God, who has put the natural light of reason into humans (Dika, 2020). Self-consciousness in Descartes is not closed on itself but is open to God, acting as a source of the objective significance of human thinking.
This proof, which can be called epistemological, is decisive for the entire system of the philosopher. As Urban (2018) argues, according to Descartes, the mind is a thinking thing, unextended, indivisible, capable of knowing the truth and striving for it, and also endowed with absolute free will. The body, conversely, is an extended and non-thinking thing; moreover, it acts automatically (Urban, 2018). Thus, Descartes believes that the human is indeed separate from the body and can exist independently of it. Theoretically, there can be no connection between these two substances, but in actual experience, a person is their inseparable unity.
Cogito is Descartes’ first reliable judgment and, at the same time, the first object directly given to the mind – a thinking substance. It is open to people directly, while the existence of the other substance, material, is given indirectly (Urban, 2018). Descartes views a substance as a thing that needs nothing but itself to exist. Analyzing this position provides the idea that only God can be called a substance. Among created things, the philosopher conventionally calls substances only those that need divine assistance for their existence. The thinking substance as an attribute is unextended and, therefore, indivisible. The substance of the body has an extension in length, width, and depth; thus, it is divisible into parts, has a figure, movement, and a certain arrangement of parts. Only these qualities are really inherent in bodily substance, and all the rest, including color, taste, smell, warmth, and others, Descartes calls secondary. Such features owe their existence to the impact of primary qualities on the body.
Ideas inherent in the thinking substance from the very beginning and not acquired through experience are innate. These include the idea of ​​God as an all-perfect being, the ideas of numbers and figures, as well as some general concepts, or axioms (Macbeth, 2017). These eternal truths are the embodiment of the natural light of the mind. Thus, Descartes draws a clear distinction between the concepts of mind and body and argues for clear differences between their functions, which is one of the main premises of his theory of transcendental idealism. The concept of substantial or Cartesian dualism proposed by him formed the basis of the philosopher’s works, who proved his ideas empirically.
Criticism Against Cartesian Substance Dualism and Descartes’ Responses
Despite his rationale for dualism in the theory of body and mind, Descartes faced objections from some other philosophers who refuted his concept. For instance, as cited in Dong (2020), Thomas Hobbes argued that the nature of the identity between thought and thinking did not allow applying a similar interpretation algorithm to other phenomena or states. According to him, Descartes identifies the subject and its abilities, and only a material subject is capable of thinking since thinking itself cannot think because this is an endless contradiction (Dong, 2020). To this, Descartes replies that he understands thinking precisely as a substance and not as an action, but this substance is spiritual and by no means material (Bardin, 2019).
After all, as Dong (2020) remarks, a substance is not learned directly but only through its accident, and if two substances have different accidents, they should be separated. A spiritual substance has such accidents as cognition, desire, fantasy, and some others, united under the name of thinking, while material substance has magnitude, form, and movement, united under the name of the extension.
This is how Descartes responds to Hobbes’ objection: if the attributes of two substances are absolutely different, it is impossible to mix these substances in thought. Otherwise, a person goes against the rule of clarity and distinctness in thinking. Such an understanding of the thinking substance provides a place for freedom; as cited in Dong (2019), people comprehend their mind independently of the body, which means that consciousness and body are different. In addition, people comprehend their will like the ability of the soul to act and think freely, which means that the will is really free. Moreover, only the soul as a finite substance can have free will since freedom is where there is a choice, and a choice is where there is something else outside the subject.
One of the most pointed arguments against Descartes’ theory was made by Gilbert Ryle. He challenged the dualistic concept of the body and mind, arguing that it was based on a category error (Nnaemeka & Chukwunenye, 2018). In addition, as cited in Christofidou (2018), in Ryle’s view, behaviorism was a much more accurate approach reflecting the motives of actions. The main claim was that, from the standpoint of science, physical action required a physical cause.
However, since, according to Descartes, the mind and body are completely different entities, their interaction becomes impossible. For the creator of the theory of dualism, there was no other rational way to answer these objections than to resort to the principle of divine intervention (Nnaemeka & Chukwunenye, 2018). Nevertheless, the concept of dualism did not receive full recognition among all philosophers without exception, although Descartes’ ideas formed the basis of many cause-and-effect concepts.

Despite the counterarguments presented, Descartes’ concept of the mind and body offers empirical justifications that are revealed through philosophical reflection. Involving the divine principle as one of the main incentives explaining the motives for specific actions corresponds to the ideas of Descartes’ contemporaries about the spirituality of any behavioral motives. The idea of ​​ Cartesian dualism, which became the basis of Descartes’ theory, received its recognition due to clear justifications regarding thinking and its participation in human development.