Questions and Lecture on Descartes' Method of Knowledge
William O'Meara (c) Copyright, 1997
1. Why was Descartes dissatisfied with his education? So what did he do?
2. What is his purpose in this reading?
3. Explain Descartes' method as a form of rationalism.
4. Explain his method of Yes and No Argumentation. Whose method was he using in an attempt to defeat his opponents?
5. Apply the method to the various items which he examines, in order to arrive at his beginning point in philosophy. [This answer requires some detail in order to show the steps through which Descartes goes.]
6. What is his beginning point? Why is this statement true for Descartes? What, if anything else, does Descartes know when he knows that famous statement of his?
7. What is his first proof of God?
8. What is the structure of the argument?
9. Is it a valid argument? Why or why not?
10. Are the premises true? Explain which you think are true and which false. If you think any premise is false, you should try to make a good argument for Descartes as to why the premise is true.
Descartes' Method of Knowledge
Descartes graduated from one of the famous schools in France and found that he was dissatisfied with his education. He tells us in the reading that "Today, for the first time, have I become aware that, from my earliest years, I have accepted a multitude of false opinions as true, and that what I have based on principles so ill-assured cannot be otherwise than extremely doubtful." (p. 55) So Descartes traveled to learn from experience. He created analytical geometry, the combination of algebra and geometry which enables mathematical students to write graphs for equations.
His purpose in this reading is to adopt a method of doubting, a methodical doubt, in order to find a perfect truth, an absolutely indubitable truth on which all knowledge could be based. In philosophy this perfect truth would be the basic postulate from which he could deduce with certainty other truths such as the existence of God. Descartes exemplifies an approach in philosophy called rationalism. A rationalist will attempt to get absolute insights into fundamental truths and to prove with certainty truths dependent upon those fundamental truths. Very often, like Descartes, the rationalist is attempting to model philosophy upon mathematics, seeking to find the basic postulate of all knowledge and to prove deductively other truths based on that basic postulate.
In the remaining paragraphs, Descartes will adopt a method of Yes and No argumentation. In the Yes, he will propose a class of truths for acceptance. Then in the No, he will raise doubts about that class of truths. He will proceed with this method of doubting until he can find an absolutely indubitable truth. This memthod is the very method which classic sceptics of ancient Greece and rome used in order to show that theoretical reasoning in philosophy would come to a paralysis of knowledge since equally plausible answers could be supplied to any abstract question in philosophy such as, "Does God exist?"
Here is Descartes' application of his Yes and No method of argument, underetaken to defeat the sceptics by using their own method:
Yes: p. 56, paragraph 1: "All that I have hitherto received as most true and assured I have learned from the senses or by means of the senses."
No: p. 56, paragraph 1: "But I have sometimes found that these senses were deceivers, and it is the part of prudence never to trust entirely those who have once deceived us."
Yes: p. 56, paragraph 2: "But although the senses may deceive us sometimes in regards to things which are scarcely perceptible and very distant, yet there are many other things of which we cannot entertain a reasonable doubt, although we know them by means of the sense; for example, that I am here, seated by the fire . . . . And how can I deny that these hands and this body are mine? Only by imitating those crazy people. . . ."
No: p. 56, paragraph 2: "Nevertheless, I have to consider that I am a man, and that I fall asleep and in my dreams imagine the same things . . . these crazy people do while they are awake." Descartes is not experiencing an emotional or practical doubt about his sanity. He is exercising a theoretical procedure of doubting in order to find an absolutely indubitable truth. Think of Descartes in this way. Even if he were crazy, could he then know some truth? Even if he were asleep, could he still know some truth. So Descartes says: "Let us, then, suppose that we are asleep, and that all these particular things - that we open our eyes, shake our heads, stretch out our hands, and such 1ike things are only false illusions."
Yes: p. 57, paragraph 1: "Whether I am awake or asleep, two and three together always make five, and a square never has more than four sides, and it does not seem possible that truths so clear and so evident can be suspected of any falsity or uncertainty."
No: p. 57, paragraph 2: "Nevertheless, for a long time I have cherished the belief that there is a God who can do everything and by whom I was made and created such as I am. But how do I know that he has not caused that there should be no earth, no heavens, no extended body, no figure, no size, no place, and that nevertheless, I should have perceptions of all these things, and that everything should appear to me to exist not exactly as otherwise than I perceive it? And even in like manner as I judge that others deceive themselves in matters that they know best, how do I know that he has not caused that I deceive myself everytime that I add two to three?"
Yes: p. 57, paragraph 2: "But it may be that God has not willed that I should be deceived in this manner, since he is called supremely good."
No: p. 57, paragraph 2: "Nevertheless, if it is repugnant to his goodness to create me such that I should deceive myself constantly, it would appear also to be contrary to it to permit me to deceive myself sometimes, and yet I cannot doubt he does permit it. ." Descartes now has doubted whether a good God exists. He expresses this doubt by going on to say: "I shall suppose, then, not that God, who is very good and the sovereign source of truth, but that a certain evil genius, no less wily and deceitful than powerful, has employed all his ingenuity to deceive me." (P. 57, paragraph 3) Descartes has supposed that some diabolical force exists which attempts to deceive him whenever he thinks. This doubt, if it were emotional and practical, would surely require psychiatric care. However, for Descartes, it is a theoretical doubt. Even in this insane doubt is it possible for Descartes to know an absolute truth. And Descartes' answer is Yes.
Yes: p. 58, paragraph 1: "There is still no doubt that I exist, if he deceives me; and let him deceive me as he may, he will never bring it about that I shall be nothing, so long as I shall think something exists. n While Descartes is thinking, he must be in order for him to think even if there is an evil deceiver who attempts to deceive him in all that he thinks. In Descartes' words, "I think, therefore I am."
Why must this statement be true, "I think, therefore I am"? The answer of Descartes is that he clearly and distinctly understands the necessary connection between the activity of his thinking and the fact of his existence. He clearly knows that his thinking is the effect of his existence. So Descartes is affirming that he knows the principle of efficient causality, namely, whatever begins to be must have a cause of its beginning to be. Descartes' thinking is something that begins to be. Thls thinking must have a cause of its beginning to be. For something cannot come from nothing. It is typical of a rationalist philosopher to affirm intuitive truths, truths which are known directly by the mind and not by sensations. Typical examples of such truths are the intuition into the truth of one's own self-awareness and the intuition of the principle of efficient causality.
Proof of God
Descartes now has the problem of getting outside of his thinking self in order to achieve knowledge of his body and the material world. In order to get back to the material world he will first have to prove the existence of God as the almighty and good being who would not allow a powerful, evil deceiver to deceive Descartes. In outline form, this is Descartes' first proof:
Descartes is aware of himself as a limited, imperfect thinker since he is aware of so many doubts.
Descartes can only know that he is imperfect by comparing himself with the idea of a being more perfect than himself.
This idea of a perfect being, namely, God, must have a cause, according to the principle of efficient causality.
The idea of a perfect being cannot be caused by Descartes, an imperfect being. At this stage of the argument, Descartes again uses his Yes and No method of argument:
No: He says that he may be more than he supposes himself to be andd that the perfections he attributes to God belong in some way potentially to him. For Descartes is aware of hls knowledge as perfecting itself little by little, overcoming imperfections gradually.
Yes: Even though Descartes' knowledge can grow and overcome limitations, this experience is not the cause of his knowledge of the idea of God. For he understands the idea of God to be the idea of a being actually infinite, not potentially infinite. In the idea of God, there is no potential. Descartes' potential perfection cannot be the source of the idea of a being who is actually perfect without any potential for increase.
Therefore, only God, the Perfect Being, is the cause.
The structure of the argument could be symbolized as follows:
First step:
If Imperfect [Descartes is an imperfect thinker], then idea of P [Descartes is comparing himself with something more perfect].
Imperfect is true [Descartes is an imperfect thinker with many doubts].
Idea of P occurs, therefore.
Second step:
If idea of P [idea of a more perfect being] occurs, then it is caused either by an I [an imperfect being] or a P [a perfect being] because anything that comes to be must have a cause of its coming to be.
Idea of P occurs.
Therefore, idea of P is caused either by I or by P.
Third step:
If idea of P cannot be caused by I [idea of a more perfect being cannot be caused by an imperfect being], then it is caused by P [a more perfect being].
Idea of P cannot be caused by I because of the following analysis in which Descartes again uses his Yes and No method of argument:
No: He says that he may be more than he supposes himself to be andd that the perfections he attributes to God belong in some way potentially to him. For Descartes is aware of hls knowledge as perfecting itself little by little, overcoming imperfections gradually.
Yes: Even though Descartes' knowledge can grow and overcome limitations, this experience is not the cause of his knowledge of the idea of God. For he understands the idea of God to be the idea of a being actually infinite, not potentially infinite. In the idea of God, there is no potential. Descartes' potential perfection cannot be the source of the idea of a being who is actually perfect without any potential for increase.
Therefore, idea of P must be caused by P.
Is the argument valid or invalid?
Each of the above arguments is valid in the logician's sense of Valid: if the premises are true, then the conclusion must be true since they all have the same mathematical structure:
If the premises, the first two statements are true, then the conclusion would necessarily be true.
Are the premises in fact true?
The teacher's analysis is that Descartes has not established that a less perfect being could not give rise to the idea of something more perfect. A person could learn from past growth and personal development that there was an improvement in one's knowledge or in one's moral behavior. Then, by projecting that growth in knowledge or in moral development even high in the future, the person who is imperfect could be the source of an idea of something more perfect.
There is also the potential problem of the fallacy of equivocation. Descartes is using 'perfect' to mean both something more perfect and something absolutely perfect. He does try to justify a transition from the more perfect to the absolutely perfect, but the teacher questions whether this transition is as clear and distinct as Descartes' rationalist method must demand.
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