Phil 21 Anderson Questions on Descartes’



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Phil 21 – Anderson Questions on Descartes’ Meditations

Spring 05


1. The point of the dream argument is to prove you are now dreaming. T or F.
2. From a commonsense perspective, all of the following beliefs could be considered rational (assume the pronoun ‘I’ refers to you the reader). Which of them would be doubtful as a result of the dream argument:

(a)I live in California.

(b)I attended such-and-such high school (fill in the name of your school).

(c)Oxygen is essential for life.

(d)Seven is a prime number.

(e)Causes precede their effects.

(f)I am reading an assignment.

(g)I expect to graduate this semester.


3. Suppose I am having experiences of growing younger as time passes, or that I am flying through the air just by flapping my arms, or some other physically impossible thing appears to be happening. I conclude from this that I must be dreaming. So we have an answer to Descartes: I can tell whether I am dreaming or not.

Is this a successful reply to the dream argument? If not, why not?


4. Descartes’ own answer to the dream argument (in Meditation VI) is that when my experiences cohere, or in his words, if I can relate my current perceptions “…with all the rest of my life”, then I must be awake. Does this resolve the problem? If not, why not?
5. The demon argument raises the possibility that our belief in a physical world external to the mind might actually be mistaken. What do we ordinarily mean by the physical world? List four central characteristics of the physical world that are not also characteristics of the mind (given Descartes' understanding of the mind).
6. If the demon argument succeeds, then we could all be under the truly gigantic illusion that there may not be a physical world. But by the terms of the argument, our experiences may not be any different from the experiences we would have if there really were a physical world. So why should we care whether the argument succeeds or not? Would it really matter?

7.A fundamental distinction is drawn in philosophy between beliefs that are confirmed or disconfirmed by the senses (empirical knowledge) and beliefs that are confirmed or disconfirmed by reason alone (a priori knowledge or knowledge of necessary truths – what Descartes seems to mean by having “clear and distinct ideas”). Which of the following statements should be classified as empirically knowable and which as knowable a priori:

(a)All squares have four sides.

(b)Every red object is colored.

(c)If A is older than B and B is older than C, then A is older than C.

(d)Every effect has a cause.

(e)Every event has a cause.

(f)Man has evolved over several million years from some ape-like ancestors.

(g)Every suspected criminal is a criminal.

(h)Every suspected criminal is suspected.

(i)If I win the California lottery, then I will be (at least for a short time) a wealthy man.
8. Descartes seems to suggest, at various places in the Meditations, that the demon hypothesis casts doubt, not only on his perceptual beliefs but on his beliefs in necessary or a priori truths as well. Why is such a suggestion self-defeating, at least if he means all of his a priori beliefs?
9. The cogito argument goes: I think, therefore I am. But since it is equally true that if I eat I must exist or if I walk I must exist, why couldn’t Descartes have argued just as effectively: I eat, therefore I am, or I walk, therefore I am?
10. Granted that the cogito argument establishes your existence as long as you are thinking, (a)Does it logically follow from that argument that when you aren’t thinking you don’t exist? (b)Does it at least logically follow that you might not exist when you aren’t thinking? Explain your answers.
11. Descartes’ proof of God in Meditation III relies on the notion that he could not have manufactured the idea of God out of other ideas he already had; the only possible cause of his idea of God must therefore be God himself. Central to his proof is the idea that God is an infinite being and he (Descartes), being finite in his powers and abilities, could never produce an idea of an infinite being on his own. Nothing less than an infinite being could cause his idea of an infinite being. Is this really true? Suggest a way we finite humans could produce a coherent idea of infinity.
12. We all hold a good many false beliefs, but why? Descartes’ explanation is that we misuse our free will when we assent to a proposition (or in his terminology, make the judgment that a certain proposition is true) that we don’t clearly and distinctly understand. This implies that we must freely choose which beliefs to hold and which not, if we are to be justified in holding them. (a) It seems extremely implausible that we freely choose all of our justified beliefs without exception. Give an example of a type of belief that you often firmly believe to be true and are justified in believing, but which it is extremely unlikely that you chose to believe. (b) Also, give an example of a belief that you probably did choose to believe. Were you justified in choosing that belief?

13. Understanding what a thing is requires grasping the essential characteristics of the thing, those properties without which it wouldn’t be the kind of thing it is. Further, in the normal case, to know the essential characteristics of a given type of thing (that is, to “have the concept of it”) is one thing, whether anything exists in reality that qualifies as an instance of that concept is another. The ontological argument however, claims there is one important exception to this: our concept of God as a supremely perfect being includes, among his essential properties, the property of existence. A being having all perfections would necessarily have to exist. It follows from this that a person who sincerely thinks he has a concept of God and yet still wonders whether God exists doesn’t really have a true concept of God. The proposition ‘God does not exist’ is contradictory. Do you see any flaw in this reasoning?


14. One of Descartes’ primary goals in writing the Meditations was to establish that he is essentially a thinking thing and that that is his only essential characteristic. This presupposes that the reader grasps the difference between essential properties and merely accidental properties. From a common sense perspective, which of the following would be true:

(a)It is essential to our concept of an automobile that it is made in a factory.

(b)It is essential to our concept of a house that it have windows.

(c)It is essential to our concept of a circle that its area is pi times the radius squared.

(d)It is essential to our concept of a mammal that it has a heart and lungs.

(e)It is essential to our concept of a human that he or she have a physical body.

15. In his second Meditation Descartes argues for the surprising conclusion that his essence does not include having a body:

I cannot doubt that I exist as a thinking thing. (From the cogito.)

I can doubt that my body exists. (From the demon argument.)

Therefore, having a body is not essential to me.



Suggest one plausible difficulty with this argument.
16. In Meditation VI Descartes surveys the commonsense reasons he had always thought, prior to undertaking his program of philosophical doubt, were adequate reasons for believing in an external world. One of those reasons was the fact that when he was using his senses (visual, auditory, etc.) the information they conveyed was not up to him or under the control of his will. Hence, they must have had an external cause. A second reason was that when he was using his senses, as opposed to his imagination, the information obtained was much more vivid and distinct. Hence, once again, they must not have been the work of his own mind. Why do these two reasons fail to justify the belief in a world outside his mind?
17. On Descartes’ theory, a person is essentially a mind, not a mind-plus-a-body. But there is very extensive causal interaction between a mind and a body; some changes in the body cause changes in the mind and conversely, some changes in the mind cause changes in the body. This is dualism with two-way causal interaction. A number of famous philosophers subsequent to Descartes accepted the dualism but rejected the two-way causal interaction. Give one plausible reason why his theory of two-way causal interaction is difficult to accept.
(18).A great deal of research on the workings of the brain has been going on in the last thirty years. One of the findings which seems to be increasingly well-confirmed is that for each distinct kind of mental state (such as the perception of colors, the feeling of pain, the recall of memory, etc.) there is an identifiable area of the brain that is activated; when a given area of the brain is damaged, the corresponding mental state does not occur. Does this discovery prove cartesian dualism is a mistaken theory of the mind? Explain your answer.


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