The questions on this page are intended to help you work out a critical evaluation of the claims given in the text.. Write out the answers in your own notes. You don't turn any of these in either

You should answer these questions after you have done the reading questions.

Answer these as well as you can based on your understanding of the assigned reading, and your own independent critical thinking.

At this point, your notes should lay out a more-or-less detailed elaboration of the following argument structure.

Descartes thinks:
1. Only that which is known for certain can count as knowledge, only things that can not be rationally doubted can count as knowledge,
2. There is always at least a shadow of doubt about the senses, so the senses cannot provide a basis for knowledge.
3. And, since a shadow of doubt exists even for mathematics, so mathematics cannot provide a basis for knowledge.
4. But, because he cannot rationally doubt his own existance, he must exist as a thinking thing.
5. And, since he senses his own ideas, those ideas exist in his mind.
6. In the "wax story," he says that the puddle of liquid is the same thing as the chunk of honeycomb he held in his hands a few minutes ago.
7. The knowledge that they're the came could not have come for the senses.
8. Because he has this knowledge that could not have come from the senses, that idea at least must be innate, so innate ideas exist.
9. The concept of "perfection" could not have come from Descartes himself, because he himself is not perfect.
10. Because the concept of "perfection" must have come from a perfect thing, that perfect thing must exist.
11. God is the only perfect thing, so the fact that a perfect thing exists means that god exists.
12. God, a perfect being, cannot allow deceit, so god's existance means that the Evil Genius cannot exist.
13. Since the Evil Genius cannot exist, our senses (and mathematics) must be reliable after all.
14. Since our senses are reliable after all, those things they tell us clearly and unequivocally must be true.
15. Since our senses tell us the external world exists, and they're reliable, the external world must exist after all.

Now, you're not going to have to understand all of the above chain of reasoning, but you are going to have to understand some of it very deeply, which means you're going to have to spend some time thinking about possible logicalproblems with various points in this argument.

The other thing I want you to understand is that, as you go down the list, each later point depends absolutely on all the points before it, so if, say, point 8 fails, all the points (9-15) after it collapse, and Descartes argument then fails to achieve it's overall goal. Seldom has there been such potential for such a small wound to prove so fatal.

For each of the steps in Descartes' argument, there are various questions we can ask about it's logical strength.

You're not supposed to deeply understand all of this. But you are supposed to spend a reasonable amount of time doing your best to understand as much of this as you can

1. Only that which is known for certain can count as knowledge, only things that can not be rationally doubted can count as knowledge,

Do we really need a standard of knowledge that is quite this strict?
What kind of standard would you think appropriate?
If it turns out that we can do with a standard that is not as strict as Descartes wants, what does that do to Descartes' argument?

2. There is always at least a shadow of doubt about the senses, so the senses cannot provide a basis for knowledge.

Is there anything you know through the senses that you think cannot be rationally doubted?

3. And, since a shadow of doubt exists even for mathematics, so mathematics cannot provide a basis for knowledge.

In your opinion, is mathematics something we know through the senses?
Or is mathematics something we can only work out in terms of pure logic?
Is "two plus two equals four" something we know to be true because we go out and physically add things to other things?
Or is it something we know because we can sit down and work it out without ever looking out into the world?

4. But, because he cannot rationally doubt his own existance, he must exist as a thinking thing.

Descartes might have proved that his thinking exists, but has he proved that any separate thing exists apart from the thinking itself?

Imagine that your neighbor's house has a perfectly green composed of nothing but grass. Now imagine that you come by one day, and you see a daisy in one corner of the lawn. The next day, there are two daisies. The day after that, there are more daisies trailing away towards the center of the lawn. Finally, there is a meandering string of daisies leading from one corner of the lawn to the other. Let us take this experience as proving that there are daisies in the lawn. If we do so, does it also prove that there is a separate, non-daisy, daisy planting thing?

If the existence of daisies in the lawn cannot prove the existence of a separate, otherwise undetectable, daisy planting thing, can the existence of thoughts prove the existence of a separate thought-making thing?

Consider also a flock of pigeons. When you see a flock of pigeons wheeling through the air, it is pretty clear that the flock exists. But does it exist separately from the pigeons? If the pigeons all dispersed to separate individual locations, would that flock still exist?

Based on this reasoning, what is a mind?

5. And, since he senses his own ideas, those ideas exist in his mind.

But do they exist like fish in a barrel, or like pigeons in a flock?

6. The concept of "perfection" could not have come from Descartes himself, because he himself is not perfect.

Why does the concept of "perfection" have to come from a perfect thing?
Is it really true that a concept that can only come from an object that has the property described by the concept?
Do we have any reason to think that we cannot get concepts from things that don't have the property described a concept?
Where does this rule that the concept must come from a thing that has the property that come from?
Is it a valid logical principle, or does it seem to be just something that Descartes made up?

Doesn't Descartes' mind also contain the concept of "sameness?"
Does god have the property of being the same as something else?
Does Descartes have the property of being the same as something else?
Can you think of a way that god could have the property of sameness?
But does a supposedly changeless god have the property of existing in different forms at different times?

7. Because the concept of "perfection" must have come from a perfect thing, that perfect thing must exist.

Do you see anything wrong with this bit of logic? (I don't, actually)
Could anything come from something that doesn't exist?

8. God is the only perfect thing, so the fact that a perfect thing exists means that god exists.

Suppose we assume that Descartes' argument works all the way up to argument 10, where he "proves" that a perfect thing exists.
Suppose we give the name "Perfecto" to the perfect thing whose existence Descartes has proved.
Has Descartes given us any reason to believe that Perfecto must be the god he believes in?
Has Descartes given us any reason to believe that Perfecto is not Brahman or Apollo?

12. God, a perfect being, cannot allow deceit, so god's existance means that the Evil Genius cannot exist.
13. Since the Evil Genius cannot exist, our senses (and mathematics) must be reliable after all.
14. Since our senses are reliable after all, those things they tell us clearly and unequivocally must be true.
15. Since our senses tell us the external world exists, and they're reliable, the external world must exist after all.

9. In the "wax story," he says that the puddle of liquid is the same thing as the chunk of honeycomb he held in his hands a few minutes ago.

But, is Descartes trying to prove that the honeycomb and the puddle are the same thing, or is he just asking us to imagine that they are the same thing?

Is he trying to prove that sensory information is reliable, or is he trying to prove that even if sensory information is reliable, there are still some things that absolutely cannot come from the senses?

10. The knowledge that they're the same could not have come for the senses.

Are we absolutely sure that knowledge of sameness doesn't come from the senses?
In the story, where does Descartes get the idea that the honeycomb and the puddle actually are the same?
Does he just assumed that that the same, or is this belief based on something?

If he just assumes that they're the same, what does that say about his argument?
Can you really prove anything based on an argument that is itself based on an assumption?

Imagine I try to prove that magical beings exist. My argument is as follows. "Dragons exist, dragons are magical beings so, since dragons exist, magical beings must exist!" If my first premise is an assumption, have it proved anything?

If Descartes's belief that they're the same thing is based on something, what could it be based on?
What are our ideas of sameness normally based on?

Suppose that while Descartes is demonstrating his wax example, you have to leave the room. Suppose that while you are out of the room, someone else brings in a honeycomb and does the same things as Descartes to it. When you come back, you see two exactly similar puddles of wax. Without talking to people who were in the room, can you tell which is which? If you do ask people who were in the room, how do they know which one is the same as Descartes's original honeycomb? Suppose Descartes was distracted, and put his wax down for a second. Suppose that, unknown to Descartes, someone substituted a different piece of wax, and Descartes went on with his demonstration all unknowing. Afterwards, he asserts with complete confidence that the puddle of wax before him is the same wax as the honeycomb he started with, even though everyone else knows it isn't. Or would he know it isn't the same wax? How would he know? How do we justify claims of sameness and difference in ordinary life? How do we learn the concepts "sameness" and "difference" in ordinary life? Is it really impossible to have gotten these ideas from sensory information?

11. Because he has this knowledge that could not have come from the senses, that idea at least must be innate, so innate ideas exist.

Well, let's think about that.
How do you know that two things are the same, anyway?
Do you ever really know, with absolute certainty, that two things are the same?
Has Descartes proved that it is ever the case that we can be absolutely certain that the evil genius has not made substitutions?
Has Descartes given us any reason to think that this supposedly innate idea is not actually an innate mistake?

How To Make Up Quizzes
If for some reason, (illness, family emergency, conflicting academic obligation, sudden discovery that you have superpowers coupled with the need to save the Earth from a hurtling asteroid that only you can deflect), you miss one of my delightful quizzes, you can make up the lost points by writing up a clear, precise, and deeply insightful answer to one of the potential exam questions and turning the results in as "make-up quiz." Illustrations are not absolutely necessary, but would add a nice touch.

Potential Exam Questions
The following questions may appear on the next exam. Your answers should fully explain and properly organize all the information relevant to each question. This will include a variety of ideas developed in response to the above questions, in your personal reading and in class discussions. Remember, the hints won't appear on the exam!

8. Explain Descartes's philosophical method and his justification for that method.
Why can't Descartes start by building on the structure of knowledge that existed before him? Does Descartes think that there are some things which are so obviously true that we don't need to worry about them? Explain. What must Descartes do before he can even begin to produce real knowledge? Explain your answers, giving Descartes's arguments where appropriate.

9. Explain Descartes's arguments why neither the senses nor mathematics can be the foundation of knowledge. 
What is Descartes's basic philosophical method? What standard must something meet in order for Descartes to accept it as a fit foundation for knowledge? Why can't the commonsense picture of the world based on the senses meet this standard? What kind of knowledge is mathematics? Why is it the kind it is? Does the truth or falsity of mathematical statements depend on the existence of a particular kind of world? Explain. How are mathematical truths determined? Do mathematical facts have the same kind of built-in uncertainty that observational facts do? Explain. Given all that, how come Descartes still can't use mathematics as his foundation?

10. Explain and Critique Descartes's famous "Cogito ergo sum" argument. 
What imaginary being does Descartes postulate in order to begin this argument? Why does he postulate this being? What kinds of beliefs are undermined by postulating this being? What exactly is proved by Descartes argument? Would you prove the same thing if you used the same argument? Explain in detail how Descartes proves what he thinks he proves. Now explain your instructor's critique of this argument. What do I think Descartes thinks he proves exactly? What do I think Descartes actually proves? What is the difference? Why is this difference a problem for Descartes?

11. Explain and Critique how Descartes uses wax to try to establish the existence of an innate idea.
What is an innate idea? What other kinds of ideas are there? How are innate ideas different from the other kind? What innate idea is generated by the wax example?  Why is this supposed to be an innate idea rather than an idea of the other kind? Now explain your instructor's critique of this argument. What do I think is wrong with Descartes argument here? What do possibilitie do I think Descartes ignores how is this fatal to his argument?

12. Explain and Critique Descartes's argument for the existence of God.
What is the basis for Descartes' argument for the existance of God? What are the two possible sources for this thing? What other explanations for this thing does Descartes rule out, and what explanation does Descartes think is left? How is this explantion related to Descartes' definition of God, and how is all this supposed to prove that God exists? What is the major flaw in Descartes' reasoning, and how does this flaw cause Descartes' argument to fail?

13. Explain and Critique Descartes's argument against the existence of the evil genius.
What claim does Descartes start with, and by what chain of reasoning does Descartes' think he has come to disprove the existence of the evil genius? What is the major flaw(s) in Descartes reasoning, and how does this flaw bring about the failure of Descartes' argument?

14. Explain and Critique Descartes's argument for the existence of the physical world. 
Beginning with the existence of God and the nonexistance of the evil genius, trace out the chain of reasoning that Descartes uses to prove the existance of the external world. In Descartes's view, after this argument, is it possible that there really is in fact no external world at all? Why or why not? Why is the definition of God important here? Why is Descartes' view of knowledge important here? What flaw(s) if any can be found in this argument, and if it is flawed, found, how does the argument fail?

Any exam answer can be enhanced by addition of any comments that occur to you. The more you think about a topic, the more likely you are to come up with something that can earn you a little more credit for your answer. I never deduct points, so it can't hurt to add your own thoughts.

Copyright © 2013 by Martin C. Young

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