Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences (French: Discours de la Méthode pour bien conduire sa raison, et chercher la vérité dans les sciences) is a philosophical and autobiographical treatise published by René Descartes in 1637.

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 is divided into six parts, described in the author's preface as: Descartes begins by allowing himself some wit: Good sense is, of all things among men, the most equally distributed; for every one thinks himself so abundantly provided with it, that those even who are the most difficult to satisfy in everything else, do not usually desire a larger measure of this quality than they already possess.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.

The greatest minds, as they are capable of the highest excellences, are open likewise to the greatest aberrations; 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, forsake it.Descartes describes his disappointment with his education: "[A]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."

Descartes was in Germany, attracted thither by the wars in that country, and describes his intent by a "building metaphor" (see also: Neurath's boat).

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.

Descartes briefly sketches how in an unpublished treatise (published posthumously as Le Monde) he had laid out his ideas regarding the laws of nature, the sun and stars, the moon as the cause of "ebb and flow" (meaning the tides), gravitation, light, and heat.

Describing his work on light, he states: [I] expounded at considerable length what the nature of that light must be which is found in the sun and the stars, and how thence in an instant of time it traverses the immense spaces of the heavens.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 somewhere in the imaginary spaces [with] matter sufficient to compose ... [a "new world" in which He] ... agitate[d] variously and confusedly the different parts of this matter, so that there resulted a chaos as disordered as the poets ever feigned, and after that did nothing more than lend his ordinary concurrence to nature, and allow her to act in accordance with the laws which he had established.Descartes does this "to express my judgment regarding ... [his subjects] with greater freedom, without being necessitated to adopt or refute the opinions of the learned."

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.

Skepticism had previously been discussed by philosophers such as Sextus Empiricus, Al-Kindi,[12] Al-Ghazali,[13] 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.