René Descartes: Discourse on the Method of Rightly Conducting the Reason

Explanation and Analysis of the Document

Chapter 1 begins with the tongue-in-cheek observation that good sense must be the most equally distributed of all things, because everyone thinks they have it in abundance—and, surely, not everyone is wrong. Descartes assumes that the power of judgment or reason is equally distributed among all human beings. The diversity of people's opinions does not derive from an unequal distribution of reason but from the fact that they do not all attend to the same objects or conduct their thoughts in the same ways. The point is not to possess reason but to apply it rightly. He says he has never considered his mind “more perfect” than anyone else's and expresses confidence that reason is “to be found complete in each individual.” He does, however, lay claim to a method by which to augment knowledge that he wants to describe.

In chapter 4, Descartes begins with radical systematic doubt. He rejects everything that admits any possibility of doubt in order to discover whether he believes anything that is indisputable. He rejects sensory perception and geometric demonstrations because both are susceptible to distortion. In the end, he arrives at the famous assertion “I think, therefore I am.” In order for systematic doubt to be put into play, there must be an “I” to doubt. He could even doubt his body or the existence of a world, but there can be no doubt that the “I” doubts, because there is no doubt without it.

This “I” is a “substance whose whole essence or nature consists only in thinking.” It needs no place, is dependent on no material thing, and is therefore entirely distinct from the body. Recognizing that there is nothing in the words “I think, therefore I am” to confirm that they are true, other than the fact of seeing clearly that “in order to think it is necessary to exist,” Descartes extrapolates a general rule: that he might take as true all things he can clearly and distinctly conceive.

Descartes then turns to the question of what taught him to think of something more perfect than himself. It goes without saying that to know is more perfect than to doubt, meaning that the doubting “I” is imperfect. This imperfect being could not be the source of thinking about perfection, so it had to come from a more perfect being. That more perfect being, Descartes reasons, must be God. As Descartes sees it, the existence of a perfect being—God—is at least as certain as any geometric demonstration. Many people are uncertain about the existence of God because they never raise their thoughts above sensible things and therefore never consider anything except by way of imagination. However, “neither our imagination nor our senses can give us assurance of anything unless our understanding intervene.”

For Descartes, the existence of a perfect being is necessary to underwrite all the imperfect beings of which we are aware and that are subject to doubt. The clearness and distinctness of ideas as the basis of our assurance runs into difficulty when we recognize that thoughts that occur in dreaming are often clearer, more vivid, and as distinct as those that occur when we are awake. So we have no straightforward way of knowing whether we are awake or dreaming. Only the existence of a perfect being can shed light on the imperfect beings we encounter.