Dualism means the complete separation of the mental world and the physical world. In philosophy, it is the theory that the universe is explicable only as a whole composed of two distinct and mutually exclusive factors: the mind and the body. Socrates and Plato are called dualists because they think that mind and body are separate and distinct substances. Mind is conscious and non-spatial and body is spatial but not conscious. While separate, these two substances interact. Both Socrates and Descartes argue that the mind and body are separable and immortal.
In the Phaedo, Socrates argues that the body is attached to the soul but that the soul can exist independently of it. In fact, as the body drags the soul around, it only confuses the soul with its senses and does not allow the soul to obtain truth and wisdom. The only way the soul can find pure knowledge or reality is to become separate from the body since “the soul reasons best when none of the senses troubles it but when it is most by itself, taking leave of the body in its search for reality” (Plato 102). In the pursuit of knowledge, the only way to discover reality is to separate the body from the soul.
This freedom from the body is called death. This does not mean that one should live in a state close to death, but one should not fear death. Socrates explains that ” our souls existed apart from the body before they took on a human form” (Plato 115). Since our souls were alive before we existed, then according to Socrates, our souls exist after death also. Souls exist in two ways after death. If a person is good and follows the practices of philosophy, then their soul will “make its way to the invisible, which like itself, the divine and immortal and wise” (Plato 120).
Here it will exist free of human ills such as ignorance, confusion, and fear, and spend its time with the gods. However, if a person thinks they know what they do not know and does not follow the practices of philosophy, then their soul will wander aimlessly until it is forced to its proper dwelling place. Descartes agrees with Plato that the mind and body are separable and infinite by using his method of doubt to show that he could not doubt the existence of his mind.
As doubting involved thought, and thought needs a consciousness to think it, Descartes was sure that he could not doubt his mind existed: cogito ergo sum “I think therefore I am”. He claims to know what a thinking think is, and he regards himself as a thinking thing. Although Descartes generally agrees with Plato on this subject, he disagrees that there is necessarily a physical body at all. Descartes did think that it was possible to doubt the existence of his body. Many times he had dreams which he found to have no basis in reality.
He imagined that a malicious demon might be fooling him into believing that he had a body. Later he argues that God exists and that as God exists he can be fairly sure that his body exits also. Descartes explained that while he could logically deny the existence of a physical substance, he cannot logically deny that of mental substance, so they must be separate. But, how do mind and matter interact? The Cartesian solution is to insist that the mental representation does not represent the physical.
However, since this does not completely explain the problem, Descartes insists that God is responsible for these interactions and only He knows how the process works. Both Descartes and Plato agree that the mind, characterized by mental substance, and the body, characterized by physical substance, are separable and immortal. However, Descartes questions whether the physical body even really exists at all. Although these philosophers do not have a clear understanding of how the mind and body, which are separate entities, interact, they clearly agree that mental and physical are separable and immortal.