Meditations on First Philosophy

Descartes inquires into whether anything can be known regarding material objects. He writes, “But before examining whether any such objects as I conceive exist outside of me, I must consider the ideas of them in so far as they are in my thought, and see which of them are distinct and which confused” (23). First, we can distinctly imagine that quantity which is called continuity, or the extension of length, breadth, or depth. We can isolate this quantity from the substance and understand it. Even if a triangle never existed outside of my mind, this triangle nonetheless is still subjected to certain rules. It maintains a nature, form, and essence that the thinker cannot change. For example, one cannot conceive of a Euclidean triangle whose angles are greater than 180 degrees. Descartes asks: if everything we clearly and distinctly perceive in an object is truly in the object, such as it is in the triangle, can we say the same of God? Descartes concludes that one can know the truth of God’s existence with as much certainty as the truths of mathematics.

While it is not necessary that we conceive of a triangle, when we do we necessarily attribute to it all the properties that bring it about and that it possesses. Yet, imagining the nature of a triangle or God does not prove these entities exist outside of the mind. Is God then a real thing or an imagined thing? He argues that in the case of God existence and essence go together. The essence of God cannot be separated from its existence because to think of God as existing only in the mind is to think of a being that is not God. God’s essence implies His existence. From a belief in God comes the ability to acquire knowledge of other things—not just things which are intellectual or pertain to God, “but also of those which pertain to corporeal nature in so far as it is the object of pure mathematics” (25).

Descartes differentiates between imagination and intellection. Descartes writes,

So that this mode of thinking [i.e., imagination] differs from pure intellection only inasmuch as mind in its intellectual activity in some manner turns on itself, and considers some of the ideas which it possesses in itself; while in imagining it turns towards the body, and there beholds in it something conformable to the idea which it has either conceived of itself or perceived by the senses (26).

Due to God’s omnipotence, we can apprehend one thing apart from another if only to assert their difference clearly and distinctly. Faculties of the mind and modes of a substance must be attached to a corporeal extended substance, and not an intelligent substance. This kind of attachment is necessary because when one clearly and distinctly perceives the faculty or mode it is the extension that is recognized and not the intellection. Thus, corporeal entities do exist on the premise that they are objects of pure mathematics. Further, if we are only thinking things with no body, then we would not feel any sensations. Descartes provides the example of a sailor noticing and then tending to a damaged part of his vessel. Our bodies are not corpses, they are intertwined with the soul. While nature teaches one “to flee from things which cause the sensation of pain, and seek after the things which communicate to me the sentiment of pleasure and so forth” they do not reveal truth without the mind carefully examining them beforehand (29). Descartes ultimately concludes that the senses provide instrumental reasoning that is easily manipulated.

Descartes makes other distinctions between mind and body in this meditation. Body is by nature divisible, while the mind is indivisible. He provides the example of losing a foot, wherein the mind is considered to remain whole. The mind also does not receive impressions from the body but from the brain, specifically where the common sense is said to reside. For example, when one part of our body contracts a part of the brain mirrors the same contraction every time. Then, the mind is affected by a sensation of pain which is represented as existing in the foot. It receives the sensation as if it experienced the pain. Lastly, the feeling is also particular, leading us to believe that it is communicated for our survival and is the most useful at that moment. The usefulness of these senses, Descartes states, is a testament to the goodness of God.

Descartes returns briefly to the possibility that he is dreaming. He concludes that, since memory cannot connect dreams, they can be distinguished from wakefulness, which is necessarily structured by a sense of continuity. Descartes ends his meditations by stating that, despite acquiring this knowledge, people are subject to the immediate requirements of action and thus sometimes forced to form judgments before careful deliberation is possible.