The start of the Scientific Revolution heralded many changes concerning different viewpoints on knowledge. The breakaway from the medieval ages and the gradual rediscovery of classical ideas from the Renaissance period gave rise to the analytical systems of thought regarding individual existence, the philosophy of the mind, and eventually, through rationalism, the formation of the natural sciences.

The breakaway from the dogmatic teachings of religion widened the opportunities of tapping into different perspectives of thought and eventually forming different disciplines which gave importance on fact, verifiability and evidence in order to determine its truth and universality. French philosopher and mathematician Rene Descartes is known for his rejection of all existing knowledge, otherwise known as the Cartesian doubt, because of the false impressions that sense perception provides in understanding knowledge.

Descartes offers a methodological doubt or the process of deduction in order to determine objects or knowledge with absolute certainty. As such, his work Meditations on First Philosophy contains ontological arguments concerning the individual existence, God, and the mind-body dualism. Considering his background on mathematics, his philosophies exemplify the attempt to determine knowledge through evidence and specification rather than mystical and often dogmatic interpretations of understanding different worldly phenomena.

Concerning the separation of the mind and body, Descartes argues on the distinction of the mind and body as a separate function where both objects can exist without dependence from the other. As mentioned in the prior discourses concerning the existence of knowable objects, Descartes proposes the existence of a perfect being or God which produces all known experiences and sensations. In relation to the sixth meditation, the importance of Descartes’ God is essential in understanding the separation of mind and body as well as providing insight toward understanding and imagination, knowledge and his complete disregard of the senses.

In the sixth meditation, Descartes constantly uses logical arguments concerning the nature of mind and body through the use of prior arguments found in the first parts of the work. God, as the ultimate creator of all objects of experience, becomes the basis for Descartes’ distinction of the mind-body problem and the existence of material objects. Descartes first distinguishes the faculties of imagination and pure understanding respectively as presented in the vision of a triangle.

According to Descartes, a triangle can be perceived in its three sides and its other properties through understanding only, meaning that the idea of a triangle is present in the consciousness that a triangle is a triangle because of its three-line composition. But it is also inevitable to conceive the triangle along with its ‘three-sidedness’ in the mind’s eye (imagination). Thus, we understand the triangle (intellect) and picture its essence in the imagination (sense). However, the weakness of imagination is evident in Descartes proposition of a thousand sided figure:

I indeed rightly conceive that it is a figure composed of a thousand sides, as easily as I conceive that a triangle is a figure composed of only three sides; but I cannot imagine the thousand sides of a chiliogon as I do the three sides of a triangle, no, so to speak, view them as present. (Descartes 92) The imagination, as presented in the example above, is not an essential part of the mind since it alone cannot determine true knowledge. Without the mind, the imagination cannot ‘picture’ the triangle without the prior understanding of ‘what is’.

The mediator or the individual would continue to exist even without mental images. Thus, Descartes places importance on the function of the mind which also relates to prior arguments concerning thought and existence. Descartes then proposes that the imagination is separate from the intellectual functions of the mind and derives its ‘source’ from something else. The difference between understanding and imagination is related to its respective functions; the processes of understanding concern the mind, where it turns upon itself to derive images of perception.

Imagination on the other hand, involves the mind relying on the body on perception. Descartes however does not entirely suppose the existence of material objects from the aforementioned arguments but merely distinguishes the two faculties through function. He further discusses the nature of sense perception concerning the body and the existence of material objects. Descartes argues that the existence of the body is also separate and has the capability to experience either beneficial or harmful sensations such as pleasure and pain.

In addition, the body is also capable of other sensations, emotions, and other appetites that Descartes assumes to come from outsides sources: And because the ideas I perceived by the senses were much more lively and clear, and even, in their own way, more distinct than any of those I could of myself frame by meditations, or which I found impressed on my memory, it seemed that they could not have proceeded from myself, and must therefore have been caused in me by some other objects.

From the following argument, Descartes logically argues for the creation of sense perception from an external source since the body has the capability to perceive such. In addition, it can be logically ruled out that the individual or the mediator cannot create such senses since such sensations are either involuntary or forced upon the body. There is no awareness on the part of the person creating such awareness involves understanding, which is a part of the intellect.

Therefore, using the arguments from the third meditation concerning the existence of God, Descartes argues that these external sensations are caused by God, who as a perfect being, does not deceive and therefore sense experience relies solely on the natural order of the environment or external consciousness: “For as he [God] has given me no faculty whereby I can discover this to be the case, but, on the contrary, a very strong inclination to believe that those ideas arise from corporeal objects” (Descartes 98). Thus, Descartes concludes the existence of the body as a separate entity from the mind for it involves certain process of perception:

Although I certainly do possess a body with which I am very closely conjoined; nevertheless, because on the one hand, I have a clear and distinct idea of myself, in as far as I am only a thinking and unextended thing, and as, on the other hand, I possess a distinct idea of body, in as far as it is only an extended and unthinking thing, it is certain that I, (that is, my mind, by which I am what I am), is entirely and truly distinct from my body, and may exist without it. (Descartes 98) Thus, the body, as a necessity of existence, can exist by itself without reliance from any detached concept, such as the body.

The mind would continue to exist even without the experience of different sensations; indeed, the idea of the body can also be conceived by the intellect. From Descartes’ arguments, the mind and body dualism points to the importance of intellectual knowledge compared to the different sensations and emotions that otherwise impede or garble the processes in ascertaining the truth. Descartes concludes the separation of the mind and body as the former is able to conceive the idea of a body and thus exists entirely for itself.

Basing from the prior arguments, Descartes espouses the important notion of a ‘thinking thing’ that necessarily exists (I think, therefore, I am). The essence of existence is on the function of thought and it alone provides existence. The body relies on sense perception provided by an external source, or in Descartes case, by God, which reflects natural inclinations such as emotions, sensations, among others. Though God as a perfect being incapable of deception, sense perception does not wholly provide truths but rather the mind contains the ideal objects that perception tries to represent.

Thus, Descartes’ arguments on the existence of material objects is reinforced with the idea of infallible sensations caused by a perfect being that guarantees its distinctiveness on external objects only However, the problem arises between the inevitable union between the two faculties; first, he argues that the mind and body are conjoined and compose a certain unity in relation to sensations such as pain, hunger, joy, sorrow, etc. Thus, the effect of the body upon the mind and vice-versa is inevitable, though their function distinctly separates itself from the other.

For example, the body experiences pain and therefore the mind reacts as though it was in pain itself. The mind cannot completely detach itself from bodily experience even if tries to view pain as a concept. Further, through the dictates of nature or the environment, the individual’s body is also surrounded by other bodies and also perceives the same sensations yet these perceptions are varied depending on the person: “I safely conclude that there are in the bodies from which the diverse perceptions of the senses proceed, certain varieties corresponding to them, although, not in reality like them” (Descartes 100).

Thus, he presents the first reason why sense perception is unreliable; the diversity of sensual perception presents a multitude of derivations that cannot be entirely be considered universal as a universal truth or in terms of knowledge, physically quantified. The senses merely provide an understanding of different sensations and of nature, its source. And according to the argument on the existence of material objects, these sensations are distinct because of God’ incapability of deception.

True knowledge, according to Descartes, relies on the function of the intellect through deduction. The separation of the mind and body is emphasized that sense perception, though it affects the rational judgment of the intellect, cannot serve as the basis of knowledge because of the separate function of the mind. However, sense perception may give an understanding of the natural world, yet this understanding is thoroughly cleansed by the functions of the intellect as the true basis for knowledge.