IB Philosophy 10.3.2 Cogito Ergo Sum: the Self as a Thinking Thing Notes

The Discovery of the Cogito

1. Having established in 10.3.1 that the method of doubt can undermine virtually all beliefs, including those based on sense perception, dreaming, and even mathematical reasoning, Descartes opens Meditation II by searching for something that resists even the evil demon hypothesis.
2. The breakthrough comes when Descartes realises that even if a supremely powerful deceiver is misleading him about everything, there is one thing the deceiver cannot do: make Descartes doubt that he himself exists. For in the very act of being deceived, Descartes must exist as the subject of that deception.
3. The argument is expressed as cogito ergo sum: "I think, therefore I am." Every attempt to doubt one's own existence presupposes that there is a thinker doing the doubting. Self-awareness is therefore self-confirming; doubt itself proves the doubter's existence.
4. The cogito is not presented as a formal syllogism ("All thinking things exist; I think; therefore I exist"). Rather, it is an immediate intuition grasped through the act of thinking itself.
   1. Descartes later clarifies that it is known through a single act of clear and distinct perception (to be explored in 10.3.3).
5. The certainty of the cogito is absolutely indubitable.
   1. Unlike beliefs about the external world, mathematical truths, or even the existence of God, the cogito cannot be false whenever it is thought. Each time Descartes thinks "I am, I exist," the proposition is necessarily true.
6. However, Descartes notes an important limitation: the cogito establishes existence only for as long as one is thinking. "I am, I exist, is necessarily true each time it is expressed by me or conceived in my mind" (Meditation II).
   1. Existence is thus tied to the continuous act of thought.
7. The cogito gives Descartes the Archimedean point (a single fixed truth from which everything else can be rebuilt) he sought: one indubitable certainty from which to reconstruct the entire edifice of knowledge. Just as Archimedes said he could move the earth if given one fixed point to stand on, Descartes needs one certain truth to get everything else started.
8. This discovery has profound implications for the Core Theme of Being Human (Unit 1). It places thought and self-awareness at the very centre of what it means to exist as a person, defining human identity primarily in terms of conscious mental activity.

The Self as Res Cogitans (Thinking Substance)

1. Having established that he exists, Descartes immediately asks what he is. His answer is that he is a res cogitans: a thing that thinks.
   1. Thinking, in Descartes' broad usage, encompasses doubting, understanding, affirming, denying, willing, refusing, imagining, and sensing.
2. This expansive definition means that all forms of conscious experience count as "thinking" for Descartes. The self is not merely an intellect that performs logical operations but a unified consciousness that experiences the full range of mental activities.
3. Crucially, Descartes argues that he can be certain he is a thinking thing while remaining uncertain about whether he has a body. This asymmetry of certainty leads him to conclude that the mind and body are distinct substances, a position that will be developed fully in 10.3.5.
4. The self as res cogitans is non-extended (it takes up no space, has no shape, and cannot be located anywhere). This is what sets the mind apart from res extensa (extended substance, Descartes' term for the physical, space-occupying world of matter).