Document – Descartes, selections from A Discourse on Method (1637)

Document

Good sense is, of all humanly attributes, the most equally distributed, for every one thinks himself so abundantly provided with it, that even those who are the most difficult to please in everything else usually do not desire a larger measure [of good sense] than they already possess. And it is not likely that they are mistaken; but instead, it is evidence that the power of judging right and distinguishing truth from error (which is properly called good sense or reason) is by nature equal in all men. Consequently, the diversity of our views does not arise from some being more endowed with reason than others, but because we conduct our thoughts along different ways, and do not view the same objects [in the same ways]. For to be possessed of a vigorous mind is not enough; the prime directive is to use it correctly. The greatest minds are capable of the highest virtues, but are also open to the greatest vices, and those who travel very slowly may yet make far greater progress, provided they keep always to the straight road, than those who, while they run, take the wrong road. . . .

From my childhood, I have been familiar with letters, and since I was given to believe that by their help a clear and certain knowledge of all that is useful in life might be acquired, I had a deep desire for instruction. But as soon as I had finished my entire course of study (at the close of which it is customary to be admitted into the order of the learned), I completely changed my opinion. For I found myself embarrassed by so many doubts and errors that I was convinced that my education had no effect other than to highlight my own ignorance. And yet I was studying in one of the most celebrated schools in Europe, in which I thought there must be learned men, if such were to be found anywhere in the world. I had learned everything that others had learned at the school, and I also had read additional books on subjects considered the most advanced and interesting. I knew the judgment which other [students] had formed of me, and I did not feel that I was considered inferior, although there were some among them who were already marked out to fill the places of our instructors. And finally, I saw that our century was flourishing, and as fertile in great minds as any preceding one. All this encouraged me to judge all other men by myself, and I therefore concluded that there was no learning in the world of the type I had previously been led to believe existed. . . .

For these reasons, as soon as my age permitted me to pass from the control of my instructors, I entirely abandoned the study of letters, and resolved no longer to seek any other science than the knowledge of myself, or of the great books of the world. I spent the remainder of my youth traveling, visiting courts and armies, holding discussions with men of different backgrounds, dispositions and ranks, collecting varied experiences, overcoming difficulties, and, above all, thinking about my experiences in order to improve myself. For it occurred to me that I should find much more truth from the thoughts and beliefs of ordinary people on matters that concern them personally. . . than in the theories conducted by a scholar in his study. . . . In addition, I always had a most earnest desire to know how to distinguish the true from the false in order that I might be able clearly to discriminate the right path in life, and proceed in it with confidence.

[But] while learning the views of different people, I found as many contradictions as I had among the opinions of the philosophers and scholars. So much was this the case that the greatest benefit which I derived from their study was . . . [that] I learned to believe in nothing too certainly until I had been persuaded by example and custom . . . and I gradually avoided many errors powerful enough to darken our natural intelligence and incapacitate us from listening to reason. But after I had been occupied several years in studying the world and gathering experiences, I finally decided to make myself the object of my study, and to employ all the powers of my mind in choosing the paths I ought to follow. This endeavor [eventually] brought me greater success than if I had never left my country or my books.

But like one walking alone and in the dark, I resolved to proceed slowly and with great care, so that if I did not much progress, I would at least guard against making too many errors. . . . First of all, I took sufficient time to satisfy myself of the nature of my task, and to determine the true method to acquire knowledge. . . . Among the branches of philosophy I had learned earlier [at school], I gave some attention to the logic of mathematics, geometrical analysis, and algebra, three sciences which I believed might contribute to my task. But I discovered that logic . . . is more useful in communicating what we already know . . . than in the investigation of the unknown. . . . This caused me to seek some other method which would have the advantages of these sciences without their limitations. . . . Believing that a few clear laws are preferable to a multitude of laws . . . I found that the following four basic rules [of logic] would prove sufficient for me, provided I took a firm and unwavering resolution never in a single instance to fail in observing them.

The first [basic rule] was never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid haste and prejudice, and to accept nothing as true except what was presented to my mind so clearly and distinctly as to exclude all ground of doubt.

The second [rule] was to divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution.

The third [rule] was to conduct my thoughts in such order that, by commencing with objects the simplest and easiest to know, I might advance step by step to the knowledge of more complex things; assigning in thought a certain order even to those objects which in their own nature do not show a natural progression.

And the last [rule] was that in every case to make enumerations so complete, and reviews so general, that I might be assured that nothing was omitted.

The long chains of simple and easy reasoning by which geometersⁱ are accustomed to reach the conclusions of their most difficult problems had led me to imagine that all things . . . are mutually connected in the same way. And that there is nothing so far removed from us as to be beyond our reach, or so hidden that we cannot discover it, provided we abstain from accepting the false for the true, and always preserve in our thoughts the order necessary for the deduction of one truth from another. . . . And, as a matter of fact, the exact usage of these few precepts gave me . . . such ease in solving problems in these sciences [geometry and algebra] that in two or three months . . . not only did I reach solutions of questions that I had formerly deemed exceedingly difficult, but I also determined the means to solve other problems I had not yet considered. . . .

But the chief ground of my satisfaction with this [analytical] method was the assurance I had of exercising my intellect in all matters, if not with absolute perfection, at least as well as possible. And besides, I was conscious that by its use my mind was becoming gradually accustomed to clearer and more distinct thinking, and I hoped . . . to apply [my analytical skills] to the difficulties of the other sciences. . . . I should not, however, have ventured at once in examining all the difficulties of all the sciences, for this would have been contrary to the order prescribed in my method. Observing that such knowledge is dependent on principles borrowed from philosophy, in which I found nothing certain, I found it necessary to begin by establishing the principles [of philosophy]. And because I knew that such an inquiry was of the greatest importance . . . I thought that I ought not to attempt it until I had reached a more mature age (being at that time only twenty-three years of age). [Instead], I decided that I should first use my time in preparation for the work, and begin by erasing from my mind all the erroneous opinions I had acquired up to that moment. . . . I decided to reject as absolutely false all beliefs that contained the least bit of doubt, in order to determine afterward whether any of my beliefs were wholly certain. Accordingly, understanding that our senses sometimes deceive us, I was willing to suppose that nothing existed precisely as it might appear. And because some men err in their reasoning . . . I also rejected all of the reasonings that I had formerly taken as proofs. And finally, when I considered that the very same thoughts which we experience when we are awake may also be experienced when we are asleep, without any one of them being true, I imagined that all of my thoughts . . . had no more reality than the illusions of my dreams. . . . But while I began to think that all was false, it was absolutely necessary that I, who was thinking, must be something. And when I observed this truth, I think, therefore I am, I was so certain that no reason of doubt could be presented by the sceptics to shake it. Therefore, I concluded that I might, without hesitation, accept this as the first principle of the philosophy I was searching for.

Next, I carefully examined what I was, and I observed that I could imagine having no body, and that there was no world nor any place in which I might exist. But I could not imagine that I was not; on the contrary, from the very fact that I doubted the truth of all things meant that I was. . . . From this I concluded that I was a substance whose whole essence or nature consists only in thinking, which has need of no place, nor is dependent on any material thing, so that I (that is to say, the mind) remains entirely distinct from the body . . . and if the [body] did not exist, the mind would still continue to be all that it is.

After this, I inquired into what is essential to the truth and certainty of a proposition, for after discovering one which I knew to be true, I thought that I must likewise be able to discover the basis of this certainty. And I observed that in the words I think, therefore I am that there is nothing which gives me assurance beyond this: that it is clearly evident that in order to think it is necessary to exist. I therefore concluded that I might take, as a general rule, the principle that all thoughts and things which we very clearly and distinctly conceive are true, even if there is some difficulty in correctly determining which objects we distinctly conceive.

Next, after thinking about the fact that I doubted, and that I was not wholly perfect (for I clearly saw that it was a greater perfection to know than to doubt), I was led to inquire from where I had learned to imagine something more perfect than myself, and I clearly recognized that I must hold this idea from some nature which really was more perfect. As for the thoughts which I had of other objects external to me, such as the sky, the earth, light, heat, and a thousand more, I had less difficulty knowing from where these came, for nothing in them seemed to render them [perfect or] superior to myself. . . . But this could not be the case with the idea of a nature more perfect than myself, for to receive it from nothing was a thing manifestly impossible. . . . The only possibility was that it had been placed in me by a nature which was in reality more perfect than I was, and which even possessed within itself all the perfections of which I could form any idea; that is to say, in a single word, God. And also, since I knew of some perfections that I did not possess, I was not the only being in existence. . . . On the contrary, there was the necessity of some other more perfect Being upon whom I was dependent, and from whom I had received all that I possessed. . . .

The reason why so many people find it difficult to know this truth [the existence of God] . . . is that they never raise their thoughts above material objects. They are so accustomed to consider nothing except by way of visualization, which is a mode of thinking limited to material objects, and so all things that cannot be visualized are considered non-existent. . . . But it seems to me that [such people] who only make use of their visualization to comprehend these ideas do exactly the same thing as if, in order to hear sounds or smell odors, they try to only make use of their eyes. . . .

If there are still individuals who are not sufficiently persuaded of the existence of God by the reasons I have given, I want them to know that all of the other truths that they know, such as having a body, and the existence of stars and an earth . . . are all much less certain. For although we have a moral assurance of these things . . . no one, unless his intellect is impaired, can deny that when the question relates to a metaphysical certainty, there remains sufficient doubts to exclude complete assurance. [For example], when we are asleep we can imagine ourselves possessed of another body and that we see other stars and another earth, when there is nothing of the kind. For how do we know that the thoughts which occur in dreaming are false rather than those which we experience when awake, since the former are often not less vivid and distinct than the latter? And though men of the highest intelligence may study this question as long as they please, I do not believe that they will be able to give any sufficient reason to remove this doubt, unless they presuppose the existence of God. For

. . . if all things which we clearly and distinctly conceive are true, it is only because God is or exists, and because he is a Perfect Being, and because all that we possess is derived from him. From this it follows that our ideas or notions, which to the extent of their clearness and distinctness are real, and proceed from God, must to that extent be true. Accordingly, [when] we have frequent ideas or notions which contain some falsity, this can only occur with [ideas] that are to some extent confused and obscure . . . and not wholly perfect. . . . But if we did not know that all which we possess of real and true proceeds from a Perfect and Infinite Being, however clear and distinct our ideas might be, we should not be able to be assured that they possess the perfection of being true.

Notes

Review

1. 1. Why did Descartes decide to make himself the initial object of his study? What were his complaints with his education?

2. 2. What are the four major precepts to Descartes’ mode of investigation? Where did he get these precepts? According to his argument, what is the problem with relying upon our senses for knowledge?

3. 3. Descartes’ famous dictum, “I think, therefore I am,” is offered as proof of his own existence. Summarize the logic of his proof. Why does he conclude that this must be the first principle of philosophy? How does he know that his existence is not merely a dream?

4. 4. How does Descartes determine that God exists? What are the strengths and possible flaws in his argument? Despite Descartes’ independent intellectual thought, why does he suggest that humans are still dependent upon God?

5. 5. Descartes argued that it was necessary to abandon all preconceptions, beliefs, and assumptions before beginning his quest for knowledge. In your final analysis, do you think he was successful, or not?