from the
Discourse on Method
of
René Descartes

[ Part Four
Proofs of the Existence of God and of the Human Soul]

(continued)

I saw that there was nothing at all in this statement, “I think, therefore I am,” to assure me that I was saying the truth, unless it was that I saw very clearly that to think one must exist. So I judged that I could accept as a general rule that the things which we conceive very clearly and distinctly are always true, but that there may well be some difficulty in deciding which are those which we conceive distinctly.

After that I reflected that I doubted many things, and that, in consequence, my spirit was not wholly perfect, for I saw clearly that it was a greater perfection to know than to doubt. I decided to ascertain from what source I had learned to think of something more perfect than myself, and it appeared evident that it must have been from some nature which was in fact more perfect. As for my ideas about many other things outside of me, as the sky, earth, light, heat, and thousands of other things, I was not so much troubled to discover where they came from, because I found nothing in them superior to my own nature. If they really existed, I could believe that what perfection they possessed might be derived from my own nature; if they did not exist, I could believe that they were derived from nothingness, that is, that they were derived from my own defects. But this could not be the explanation of my thought or idea of a being more perfect than my own. To derive it from nothingness was manifestly impossible, and it is no less repugnant to good sense to assume what is more perfect comes from and depends on the less perfect than it is to assume that something comes from nothing, so that I could not assume that it came from myself. Thus the only hypothesis left was that this idea was put in my mind by a nature that was really more perfect than I was, which had all the perfections that I could imagine, and which was, in a word, God. To this I added that since I knew some perfections which I did not possess, I was not the only being in existence—I will here use freely, if you will pardon me, the terms of the school—and that it followed of necessity that there was someone else more perfect upon whom I depended and from whom I had acquired all that I possessed. For if I had been alone and independent of anything else, so that I had bestowed upon myself all that limited quantity of value which I shared with the perfect Being, I would have been able to get from myself, in the same way, all the surplus which I recognize as lacking in me, and so would have been myself infinite, eternal, immutable, omniscient, omnipotent, and, in sum, I would possess all the perfections that I could discover in God.

[ Part Five
Some Questions of Physics]

I did not wish to infer from all this that the world had been created in the manner I proposed, for it is much more likely that God created it in the beginning in the form it was to assume. But it is certain, and this is an opinion commonly held by theologians, that the action by which the world is now conserved is precisely the same as that by which it was created. Even therefore, if God had given the world in the beginning no other form but chaos, and had only established the laws of nature and given his concurrence for the world to behave as it usually does, one can believe, without injustice to the miracle of creation, that all material objects could have become, in time, such as we see them at present. Their nature is much easier to conceive when one pictures their gradual growth in this manner rather than considering them as produced in their completed state.

Here I paused to show that if there were any machines which had the organs and appearance of a monkey or of some other unreasoning animal, we would have no way of telling that it was not of the same nature as these animals. But if there were a machine which had such a resemblance to our bodies, and imitated our actions as far as is morally possible, there would always be two absolutely certain methods of recognizing that it was still not truly a man. The first is that it could never use words or other signs for the purpose of communicating its thoughts to others, as we do. It is indeed conceivable that a machine could be so made that it would utter words, and even words appropriate to physical acts which cause some change in its organs [...] But it could never modify its phrases to reply to the sense of whatever was said in its presence, as even the most stupid men can do. The second method of recognition is that, although such machines could do many things as well as, or perhaps even better than, men, they would invariably fail in certain others, by which we would discover that they did not act by understanding, but only by the disposition of their organs.

I then described the rational soul, and showed that it could not possibly be derived from the powers of matter, like the other things I have spoken about, but must have been specially created. I showed also that it would not suffice to place it in the human body, as a pilot in a ship, unless perhaps to move its parts, but that it must be more intimately joined and united with the body in order to have feelings and appetites like ours, and so constitute a real man. For the rest, I elaborated a little on the topic of the soul on account of its great importance; because, next to the error of those who deny God, which I think I have sufficiently refuted, there is none which is so apt to make weak characters stray from the path of virtue as the idea that the souls of animals are of the same nature as our own, and that in consequence we have no more to fear or to hope for after this life than have the flies and ants. Actually, when we know how different they are, we understand more fully the reasons which prove that our soul is by nature entirely independent of the body, and consequently does not have to die with it. Therefore, as long as we see no other causes which might destroy it, we are naturally led to conclude that it is immortal.

[ Part Six
Some Prerequisites for Further Advances in the Study of Nature]

Three years ago, when I had completed the treatise containing all these matters, and when I was beginning to review it for purposes of publication, I learned that people to whom I defer, and whose authority over my actions is hardly less than that of my own reason over my thoughts, had disapproved of a hypothesis in the field of physics that had been published somewhat earlier by another person. I do not want to say that I had accepted that hypothesis, but at least before their censure I could not imagine that it was prejudicial to religion or to the state, and therefore I could see no ground for not professing it if reason convinced me of its truth. This circumstance made me fear that there might be other opinions of mine in which I was misled, despite the great care I had always taken not to accept any new ones which were not very certainly demonstrated, and to write of none that might prove disadvantageous to anyone. This occurrence was enough to make me change my resolution to publish the treatise [...]

I have never entertained any pretensions about the products of my thinking. When the result of the application of my methods was merely my own satisfaction concerning some speculative questions, or perhaps the regulation of my own behavior by the principles which it showed me, I did not feel obliged to write of them. For when it comes to morals, everyone is so convinced of his own good sense that there might be as many reformers as individuals if others than those whom God has established as sovereigns over his peoples, or to whom he has given enough grace and zeal to be prophets, were permitted to attempt reforms.

It is true that as far as the related experiments are concerned, one man is not enough to do them all; but he could not usefully employ other hands than his own, unless those of workers or other persons whom he could pay. Such people would do, in the hope of gain, which is a very effective motive, precisely what they were told. As for those volunteers who might offer to do it out of curiosity or the desire to learn, besides the fact that ordinarily they are stronger in promises than in performance and that they make nothing but beautiful proposals of which none ever succeeds, they would infallibly expect to be paid by the explanation of some difficulties, or at least in compliments and useless conversation, which would necessarily consume so much of the time needed for investigation that the assistance would be at a net loss.