Study Questions (and some explanations) for Descartes, Meditation Three

Note: numbers in parentheses refer to the numbers in the margins of your text, which are the page numbers of the standard Adam and Tannery (AT) edition of Descartes’ collected works and are included in most translations.

1. At the beginning of Meditation Three Descartes takes stock. What does he say he can know for sure at this point?

2. What general rule does he posit for determining what is true? How does he justify adopting this rule? (AT 35)

3. Note that Descartes says (end of AT 36) that he can be completely certain of anything only if he can know that there is a God who is not a deceiver. Why does he need to know this in order to be sure of his other knowledge?

4. What classes of thoughts does Descartes identify? (AT 37) (Note: “affect” means roughly “emotion or feeling”; a volition is an act of will.)

5. What reason does Descartes give for thinking that what he knows “by the light of nature” must be true? (AT 38-39) How are these beliefs different from those he tends to acquire “naturally”?

6. At AT 40 Descartes begins a chain of reasoning (the so-called ‘trademark argument’) that leads him to the conclusion that God exists. To follow his reasoning we need to understand some terminology that he has taken from the medieval scholastic tradition in which he was schooled.

a. Substance, attribute, mode – Substance is the underlying stuff which has various properties, characteristics or (as the tradition puts it) attributes. A mode is a particular variant of an attribute. Consider a piece of wood that has been made into a square tabletop. The substance is the wood, one of its attributes is shape, and squareness is the particular mode of that attribute in this case.

b. Actual or formal reality vs. objective reality -- “Objective reality” means almost the opposite of what you might think it means. If we said that something had ‘objective reality’, we would probably mean that it really exists. When Descartes talks about objective reality he is talking about ideas. An idea has objective reality insofar as it represents a real object. If the object of the idea (what the idea depicts or represents) is real, then that object has formal or actual reality.

c. Descartes is thinking that some things are realer than others. This way of thinking is one that he inherited from his medieval predecessors. It is a descendent of Aristotle’s idea of a hierarchy of kinds of things. Descartes says that substances are more real than their accidents, and infinite substances are more real than finite substances. Consequently some ideas have more objective reality (in Descartes’ sense) than others. The degree of objective reality of an idea is proportional to the degree of actual or formal reality of its object, of what it represents.

d. So (to put this all together) my idea of a particular table (the one I am writing at, say) has the same degree of formal reality as my idea of a color (an accident, i.e., a property or quality of things like tables). They are each equally real as ideas that exist in my mind. But my idea of the table has more objective reality than my idea of the color, because the table is a substance, whereas the color is an accident. My idea of God, a perfect being, has the most objective reality of all.

7. What self-evident principle does Descartes announce near the beginning of AT 41?

8. How does he then use this principle to argue for the existence of God? (The argument concludes half way between AT 45 and 46.)

9. Notice that Descartes raises and answers several objections to his own argument. (AT 45-51)

10. How does he then argue (at AT 52) that God cannot be a deceiver?