In M5, Rene Descartes explores the essence of material objects and argues for the real existence of such objects. Central to this argument is his claim that the “clear and distinct” ideas we have of certain qualities of material things, such as extension, shape, and number, point to the truth of their existence. Descartes carefully examines how these ideas arise and why they must correspond to real properties of material objects.
In the earlier meditations, Descartes arrives at the conclusion that what he clearly and distinctly perceives must be true due to the existence of God. In M5, he applies this principle to the qualities of material objects. For instance, Descartes refers to geometrical properties of triangles. If he imagines a triangle, he can clearly and distinctly perceive that “three angles equal two right angles, that its greatest side subtends its greatest angle.” (7:64) The fact that these properties come to mind “whether I want to or not,” (7:64) Descartes argues, show that these qualities are not invented or uncertain, but are real and true features of the objects we think about.
He further applies this reasoning to material things as a whole, suggesting that the qualities we perceive are no less certain and real than the mathematical truths. When we think of a material object, we think of its “extension of the quantity (or rather of the thing which is quantified) in length, breadth and depth” (7:63) and its capacity to occupy space; consequently enumerating “various parts of the thing, and to these parts I assign various sizes, shapes, positions and local motions” (7:63), and finally durations. These are the essential qualities of material things, and Descartes contends that we perceive them clearly and distinctly because of their independence to the mind: “things which were long present within me although I had never turned my mental gaze on them before.” (7:64)
He further applies this reasoning to material things as a whole, suggesting that the qualities we perceive are no less certain and real than the mathematical truths. When we think of a material object, we think of its “extension of the quantity (or rather of the thing which is quantified) in length, breadth and depth” (7:63) and its capacity to occupy space; consequently enumerating “various parts of the thing, and to these parts I assign various sizes, shapes, positions and local motions” (7:63), and finally durations. These are the essential qualities of material things, and Descartes contends that we perceive them clearly and distinctly because of their independence to the mind: “things which were long present within me although I had never turned my mental gaze on them before.” (7:64)
He goes on to rebut the point that these clear and distinct ideas come from the external world. They must not have come from the senses, as one is capable of imagining unseen shapes “countless other shapes which there can be no suspicion of my ever having encountered through the senses, and yet I can demonstrate various properties of these shapes.” (7:65) Furthermore, these ideas cannot have been fabricated due to his clear awareness as demonstrated before.
Inconclusion, Descartes makes an argument for the real existence of material objects based on the clarity and distinctness of our ideas of their essential qualities. By emphasizing the certainty of geometrical and mathematical truths, he illustrates that the qualities we perceive in material things of extension, shape, and number correspond to real properties of the external world. Descartes’ reasoning builds upon the principle of clear and distinct perception, showing that material objects must possess the qualities we perceive in them and that these qualities are objective truths.