Descartes also believes that each part of the mind has its own existence and its own nature. For this reason, he opposed pantheism and called the one indivisible God mind. Descartes believed that the mind is not a material substance like a body, but, on the contrary, the possibility of realization.
Descartes’s views were based on the writings of his predecessor, Scotus Eriugena, but also required a lot of research on the part of Descartes. His decision to limit his research to the psychic life led to the development of Cartesianism. To explain reason, Descartes developed a set of «requirements for incompatibility between mind and matter» (rational thinking and concrete objects). The basis for this disagreement is that Descartes and some of his predecessors considered matter to be a universal substance, while others thought that mind was a universal substance.
Descartes believed that what people experience is based on what is happening in their brain. He believed that when people think something, the thought moves through the nerves and muscles of the head until it reaches the conscious mind. For this reason, he believed that there is a mind and a body, and that each of them has its own existence, since he believed that the soul is both material and immaterial. As a result, the concept of dualism plays a vital role in his thinking, and he argued that matter is the only substance, while matter and spirit are separate and not completely complementary. In the Third Meditation, Descartes describes how if someone looks at their hand and thinks it is a hand, then they perceive the subjective impression of the hand. This led him to believe that mind and body are not one but two parts of the mind, so that the mind cannot cause the body to appear, but the body can cause the mind to appear. Descartes believed that the ability of the body to cause the emergence of mind is the basis of the idea of free will. Descartes wrote that he still believed in free will. Descartes argued that the mind can determine the will. And this decision to do something is made freely, because the mind in its «logical and systematic procedure» generates a logical conclusion based on the premises of the situation. Descartes wrote that the mind has the power to make will because of its ability to generate a logical conclusion based on the facts of the present. The ability to form a will depends on intelligence and reason. The mind determines what it considers to be good reasons for decisions. Moreover, the mind can distinguish between different criteria and is not able to make decisions based only on knowledge. Descartes’ reflections on free will have been quoted in the debate on libertarianism.