There is the standing philosophical belief that the mind, or sometimes referred to as the soul by several philosophers, is unique and separate from the corporeal entity called brain. It denies that the mind is synonymous, at least in idea, to that of the brain and that the functions of the brain are distinct from the operations of the mind. Moreover, dualism also asserts the wide difference between the physical and mental properties in an individual in the sense that both have properties that appear to be irreconcilable.
One argument that can be raised in support of dualism is the theory of interactionist dualism espoused by Rene Descartes in his Meditations which was further strengthened and defended by John Carew Eccles as well as Karl Popper. This theory raises the argument that our desires and beliefs as states of the mind is causally brought into interaction with our physical properties.
It is believed in this theory that one may actually possess clear and distinct idea with regards to one’s mind as a thinking thing that has no form of special extension in the sense that it is impossible to grant it forms of measurement such as that of height and weight. In a seemingly similar light, one can also have a clear and distinct idea of one’s physical body as a corporeal entity that can be measured in many ways and that can be quantified inasmuch as it is also unable to think.
This line of argument represents the essential distinction being put forward by interactionist dualists between the mind and the body. The more crucial idea being espoused in this theory is that these mental states possess a causal effect or a set of causal effects on one’s physical being which is also true the other way around. For example, a man is made to experience a burning stick by touching it thereby inflicting pain on the person which, in turn, causes the individual to scream in pain which further binds him to a sense of anxiety or fear at the sight of the burning stick.
One can also arrive at an argument for the establishment of dualism by analyzing the concept of intentionality. In simplified terms, intentionality is the ability of the states of the mind to be placed in relation to or be placed in the direction of objects that are in the external world. By external world what is being meant is the realm outside the so-called self. Such mental state properties emphasizes that they have in them contents as well as semantic referents thus granting them the possibility of being given truth valuations (Searle).
Further, the attempt at merely reducing these mental states into a form of natural processes brings us to the problem that such natural processes cannot be granted with any valuation for truth or falsity for the reason that natural processes simply happen as they are. Inasmuch as these natural processes cannot be granted with the value of truth, it must be noted that the ideas brought forward by these mental processes are in relation to facts in order for them to be granted with truth.
More importantly, there arises the question as to where these forms of relations are derived from. It simply cannot be given to the brain for the brain is merely an entity that functions through electrochemical processes. If this is the case, then the brain is not responsible for these relations. Significantly, these relations are to be relegated to the functioning of the mind. That is, these forms of relation are due to the mental processes and not because of the electrochemical processes of the brain. Hence, the dualist point of view remains.