Philosopher and mathematician, Rene Descartes, wrote about "the mind-body problem” in the Meditations (1641). When asking the question "What am I?” Descartes concluded, "I am a thinking thing”. He reaches this conclusion by reasoning that he can doubt that he has a body, therefore he can doubt he is a material thing. But he cannot doubt that he is a conscious, thinking being. Descartes theory of Cartesian Dualism states that the mind and body are entirely distinct from one another. The mind could also exist without the body, as the body is not essential to what we are. They are also opposite in nature. The mind is unextended and indivisible, whereas the body is extended and divisible. .
However, if the mind and body are separate entities how and why do we feel pain, pleasure and other sensations? Descartes, although believing the mind and body are separate, does admit that they are closely related to each other, forming a union. He states "I am not merely present in my body as a sailor is present in a ship, but that I am very closely joined, and, as it were, intermingled with it, so that I and the body form a unit”. When we feel a tugging sensation in our stomach known as hunger, we know to eat something. When our throats feel dry known as thirst, we know to drink. Descartes could not explain this interaction between the body and mind, except to say that nature has taught us what action to take when we experience certain sensations. .
He goes on to define sensations such as "nothing but confused modes of thinking which arise from the union and, as it were, intermingling of the mind with the body”. .
There are a number of objections to Cartesian dualism. P.F. Strawson placed his objections in his paper 'Self, Mind and Body' (1974a). To begin with, Strawson points out that a Cartesian would have to agree that a predication of a person could be considered as two parts, considering Cartesian dualism declares that the mind and body are two separate entities.