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: Dioptrique, Météores and Géométrie. La Géométrie contains Descartes's initial concepts that later developed into the Cartesian coordinate system. The text was written and published in French rather than Latin, the latter being the language in which most philosophical and scientific texts were written and published at that time. 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: "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 common place 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, or 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 lay 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. The following three maxims were adopted by Descartes so that he could effectively function in the "real world" while experimenting with his method of radical doubt. They formed a rudimentary belief system from which to act before he developed a new system based on the truths he discovered using 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. 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

Here he describes how in other writings he discusses the idea of laws of nature, of the sun and stars, the idea of the moon being the cause of ebb and flow, on gravitation, and going on to discuss light and fire.
Describing his work on light, he states:
His work on such physico-mechanical laws is, however, projected into a "new world." A theoretical place God created
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 examing 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, which are identified as our faculty for rational thinking. Hence the term "I think, therefore I am." All three of these words can be identified by the single French term âme.

Part VI: Prerequisites for advancing the investigation of Nature

Descartes begins by noting, without directly referring to it, the recent trial of Galileo for heresy and the condemnation of heliocentrism; he explains that for these reasons he has been slow to publish.
Secure on these foundation stones, Descartes shows the practical application of "the Method" in Mathematics and the Science.

Influencing future science

Skepticism had previously been discussed by philosophers such as Sextus Empiricus, 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