Discourse on the Method


Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences is a philosophical and autobiographical treatise published by René Descartes in 1637. It is best known as the source of the famous quotation "Je pense, donc je suis", which occurs in Part IV of the work. A similar argument without this precise wording is found in Meditations on First Philosophy, and a Latin version of the same statement, "Cogito, ergo sum", is found in Principles of Philosophy.
Discourse on the Method is one of the most influential works in the history of modern philosophy, and important to the development of natural sciences. In this work, Descartes tackles the problem of skepticism, which had previously been studied by other philosophers. While addressing some of his predecessors and contemporaries, Descartes modified their approach to account for a truth he found to be incontrovertible; he started his line of reasoning by doubting everything, so as to assess the world from a fresh perspective, clear of any preconceived notions.
The book was originally published in Leiden, in the Netherlands. Later, it was translated into Latin and published in 1656 in Amsterdam. The book was intended as an introduction to three works: La Dioptrique, , and La Géométrie. La Géométrie contains Descartes's initial concepts that later developed into the Cartesian coordinate system. The text was written and published in French so as to reach a wider audience than Latin, the language in which most philosophical and scientific texts were written and published at that time, would have allowed. Most of Descartes' other works were written in Latin.
Together with Meditations on First Philosophy, Principles of Philosophy and Rules for the Direction of the Mind, it forms the base of the epistemology known as Cartesianism.

Organization

The book is divided into six parts, described in the author's preface as:
  1. Various considerations touching the Sciences
  2. The principal rules of the Method which the Author has discovered
  3. Certain of the rules of Morals which he has deduced from this Method
  4. The reasonings by which he establishes the existence of God and of the Human Soul
  5. The order of the Physical questions which he has investigated, and, in particular, the explication of the motion of the heart and of some other difficulties pertaining to Medicine, as also the difference between the soul of man and that of the brutes
  6. What the Author believes to be required in order to greater advancement in the investigation of Nature than has yet been made, with the reasons that have induced him to write

    Part I: Various scientific considerations

Descartes begins by allowing himself some wit:
A similar observation can be found in Hobbes, when he writes about human abilities, specifically wisdom and "their own wit": "But this proveth rather that men are in that point equal, than unequal. For there is not ordinarily a greater sign of the equal distribution of anything than that every man is contented with his share," but also in Montaigne, whose formulation indicates that it was a commonplace at the time: "Tis commonly said that the justest portion Nature has given us of her favors is that of sense; for there is no one who is not contented with his share." Descartes continues with a warning:
Descartes describes his disappointment with his education: "s soon as I had finished the entire course of study…I found myself involved in so many doubts and errors, that I was convinced I had advanced no farther…than the discovery at every turn of my own ignorance." He notes his special delight with mathematics, and contrasts its strong foundations to "the disquisitions of the ancient moralists towering and magnificent palaces with no better foundation than sand and mud."

Part II: Principal rules of the Method

Descartes was in Germany, attracted thither by the wars in that country, and describes his intent by a "building metaphor". He observes that buildings, cities or nations that have been planned by a single hand are more elegant and commodious than those that have grown organically. He resolves not to build on old foundations, nor to lean upon principles which he had taken on faith in his youth. Descartes seeks to ascertain the true method by which to arrive at the knowledge of whatever lies within the compass of his powers. He presents four precepts:

Part III: Morals and Maxims of conducting the Method

Descartes uses the analogy of rebuilding a house from secure foundations, and extends the analogy to the idea of needing a temporary abode while his own house is being rebuilt. Descartes adopts the following "three or four" maxims in order to remain effective in the "real world" while experimenting with his method of radical doubt. They form a rudimentary belief system from which to act before his new system is fully developed:
Finally, Descartes states his resolute belief that there is no better use of his time than to cultivate his reason and to advance his knowledge of the truth according to his method.

Part IV: Proof of God and the Soul

Applying the method to itself, Descartes challenges his own reasoning and reason itself. But Descartes believes three things are not susceptible to doubt and the three support each other to form a stable foundation for the method. He cannot doubt that something has to be there to do the doubting: I think, therefore I am. The method of doubt cannot doubt reason as it is based on reason itself. By reason there exists a God, and God is the guarantor that reason is not misguided. Descartes supplies three different proofs for the existence of God, including what is now referred to as the ontological proof of the existence of God.

Part V: Physics, the heart, and the soul of man and animals

Descartes briefly sketches how in an unpublished treatise he had laid out his ideas regarding the laws of nature, the sun and stars, the moon as the cause of "ebb and flow", gravitation, light, and heat. Describing his work on light, he states:
His work on such physico-mechanical laws is, however, framed as applying not to our world but to a theoretical "new world" created by God
Descartes does this "to express my judgment regarding ... with greater freedom, without being necessitated to adopt or refute the opinions of the learned."
He goes on to say that he "was not, however, disposed, from these circumstances, to conclude that this world had been created in the manner I described; for it is much more likely that God made it at the first such as it was to be." Despite this admission, it seems that Descartes' project for understanding the world was that of re-creating creation—a cosmological project which aimed, through Descartes' particular brand of experimental method, to show not merely the possibility of such a system, but to suggest that this way of looking at the world—one with no assumptions about God or nature—provided the only basis upon which he could see knowledge progressing.
Thus, in Descartes' work, we can see some of the fundamental assumptions of modern cosmology in evidence—the project of examining the historical construction of the universe through a set of quantitative laws describing interactions which would allow the ordered present to be constructed from a chaotic past.
He goes on to the motion of the blood in the heart and arteries, endorsing the findings of "a physician of England" about the circulation of blood, referring to William Harvey and his work De motu cordis in a marginal note. But then he disagrees strongly about the function of the heart as a pump, ascribing the motive power of the circulation to heat rather than muscular contraction. He describes that these motions seem to be totally independent of what we think, and concludes that our bodies are separate from our souls.
He does not seem to distinguish between mind, spirit, and soul, all of which he identifies with our faculty for rational thinking. Hence the term "I think, therefore I am." All three of these words can be signified by the single French term âme.

Part VI: Prerequisites for advancing the investigation of Nature

Descartes begins by obliquely referring to the recent trial of Galileo for heresy and the Church's condemnation of heliocentrism; he explains that for these reasons he has held back his own treatise from publication. However, he says, because people have begun to hear of his work, he is compelled to publish these small parts of it in order that people not wonder why he doesn't publish.
The discourse ends with some discussion of scientific experimentation: Descartes believes that experimentation is indispensable, time-consuming, and yet not easily delegated to others. He exhorts the reader to investigate the claims laid out in Dioptrique, Météores, and Géométrie and communicate their findings or criticisms to his publisher; he commits to publishing any such queries he receives along with his answers.

Influencing future science

Skepticism had previously been discussed by philosophers such as Sextus Empiricus, Al-Kindi, Al-Ghazali, Francisco Sánchez and Michel de Montaigne. Descartes started his line of reasoning by doubting everything, so as to assess the world from a fresh perspective, clear of any preconceived notions or influences.
This is summarized in the book's first precept to "never to accept anything for true which I did not clearly know to be such". This method of pro-foundational skepticism is considered to be the start of modern philosophy.

Quotations

  • "The most widely shared thing in the world is good sense, for everyone thinks he is so well provided with it that even those who are the most difficult to satisfy in everything else do not usually desire to have more good sense than they have. It is not likely that everyone is mistaken in this…"
  • "I know how very liable we are to delusion in what relates to ourselves; and also how much the judgments of our friends are to be suspected when given in our favor."
  • "… I believed that I had already given sufficient time to languages, and likewise to the reading of the writings of the ancients, to their histories and fables. For to hold converse with those of other ages and to travel, are almost the same thing."
  • "Of philosophy I will say nothing, except that when I saw that it had been cultivated for so many ages by the most distinguished men; and that yet there is not a single matter within its sphere which is still not in dispute and nothing, therefore, which is above doubt, I did not presume to anticipate that my success would be greater in it than that of others."
  • "… 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 book of the world.…"
  • "The first was to include nothing in my judgments than what presented itself to my mind so clearly and distinctly that I had no occasion to doubt it."
  • "… In what regards manners, everyone is so full of his own wisdom, that there might be as many reformers as heads.…"
  • "… And although my speculations greatly please myself, I believe that others have theirs, which perhaps please them still more."