Notes for Meditation II
Recall from Meditation I that Descartes is searching for a secure foundation of knowledge, which he has argued cannot come from empirical sources (the senses).
I. The Cogito: In par. 3, Descartes claims finally to have found something that he cannot doubt, and from that, thinks that he can derive the certainty of his own existence:
(1) It is indubitable and self evident that if I think, then I would have to exist.
(2) It is indubitable and self evident that I do indeed think.
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(3) It is thus indubitable and self evident that I exist.
Support for premise (2): It would be self-defeating to doubt that you are thinking, for doubting itself is a form of thinking. Not even an evil demon can deceive you into falsely believing you are a thinking thing, because your capacity to be deceived already implies that you are able to have thoughts.
Query: How extensive is this proof? Does it prove to you (the reader) that Descartes exists? Can I use the cogito to prove to you that I exist? Notice that the cogito is essentially first-personal (or subjective), which is why Descartes wrote the Meditations in the first-person.
II. So Descartes has proved that "I" exist. But what can be said for sure about this thing?
A. I can doubt that I am an embodied thing, surrounded by a material world.
-I can doubt that I have a head, hands, a brain, etc.
B. I cannot doubt that I am a thing that thinks, a thing that doubts, affirms, understands, denies, wills, and has ideas and sensations. (Top of p. 120)
C. The point: Descartes thinks that the contents of one’s mental lives are known with much greater certainty than things in the external world. While one might well challenge your belief that there is actually a pink rabbit in front of you, one cannot justifiably challenge the fact that you have the idea of a pink rabbit in front of you.
III. Rationalism: Descartes is a rationalist: he believes knowledge is best gained, not through the senses, but rather through the careful examination of one’s ideas through the intellect.
Two examples of the rationalist’s method:
i. The idea of oneself: In the cogito, we acquired certain knowledge of our own existence and what kind of thing we are through the intellectual means, and not through the senses (indeed the sense would have told us all sorts of dubitable things, such as that we have hands and a face!).
ii. The rationalist’s method will work even concerning our ideas of material objects (the piece of wax):
Descartes asks: What are the essential properties of an ordinary physical object, say, a piece of wax?
1. The senses tell us that the wax is yellow, that it is cool to the touch, that it has a certain shape, that it smells like flowers and tastes like honey.
2. However, when we bring the wax close to a fire, all of these sensuous properties change: it becomes clear, hot, and loses its shape, smell, and taste.
3. So Descartes concludes that none of these sensuous properties belong essentially to that piece of wax. Instead, they arise only as it interacts with our sensory organs.
4. Now Descartes asks; what belongs to the wax "itself" -- independent of our sensation of the wax. What must be true of it in each and every appearance of it to us? Descartes concludes that what must belong to a material object like the wax is simply that it persists in time and space (that it is "extended"). [Note that these are quantitative properties.]
5. Descartes thinks that we’ve arrived at these conclusions by stripping the wax of all of the properties we perceived it to have. What is left is what we "grasp" of the wax, not through the sense, but rather through our intellectual faculties.
An Objection: Don’t we "observe" persistence in time and space, just like we do those other properties? Why shouldn’t we think of "extension" as also a sensory property? Furthermore, perhaps wax is essentially the kind of stuff that undergoes particular types of observable changes. (In fact, don’t we reidentify the wax over time by observing the relevant changes?) If so, then knowledge of the nature of the piece of wax could still come from sense perception.