Descartes’ Discourse on Method

Descartes’ Discourse on Method, Clearly and Distinctly Summarized


Once upon a time in a century not too distant from our own, there lived a man named René Descartes who put forward his “paths” to knowing as if in a “fable” encouraging men to follow his trail. This Descartes lived in a world where all men were endowed with “good sense” (by virtue of their form or nature being consistent). Therefore, all that was necessary to bring about agreement was a sufficiently well established path, a method. So this Descartes set out to do a service to his fellow man by laying a path that could not cause stumbling, an indubitable one. (And all men lived…dare I say happily ever after?) This path is the topic of his Discourse on Method.

From the beginning of his Discourse, Descartes is clearly troubled with difference in belief. Moreover, it seems to be a source of great discomfort for him not to know whom or what to believe. But this troubles us all. For Descartes the situation is worse because he also believed that reason is the form of man that all men held in common.[1] So for Descartes the difficult question is not if truth exists (as we ask), but how is one to account for error? He is left in the doubly difficult position of explaining difference of opinion and holding a strong account of universal Reason.

Reason is for Descartes the (God given) power for judging what is by way of clear and distinct ideas. The notion of “clear and distinct” is similar to Plato’s notion that reason contains forms that it matches with images produced by the imagination to accurate perception. Descartes seems to think that reason is primary in this way, that perception or imagination (with which it cooperates) only serve reason with impressions of the outside world that reason takes full responsibility for.[2] So it is, Descartes presents as a paradigmatic rule that any idea which reason accepts must be “so clearly and so distinctly” to be beyond doubt. You might call this a snap-to-grid account of reason. When an idea is clear, you have clearly hit a gridline of reality. The source of error is undisciplined ventures of belief by people who accept as true what was not “clear and distinct.” These accepted false notions must be cleared away to pave the road for clear and distinct knowing. So Descartes lives as a “spectator” for nine years traveling the world, essentially living as a modern Socrates. The effect of his travels is to convince him that he does not know a great many things; it effects a clearing away of his knowledge by mere custom.

Next, secluding himself, Descartes seeks to lay sufficiently firm foundations (indubitable) for his entire project of knowing. He applies himself to doubting everything, opinions of morality, sense perception, even mathematics. He finds that while doubting he is thinking and he cannot doubt that he is thinking: cogito ergo sum, “I think, therefore, I am.” This is his first principle of knowing, and from here he understand the essence of his nature, a thinking person independent of matter. From here he judges that what he could conceive very clearly and distinctly is true. And since he can conceive of a being more perfect that himself, it must both exist and must not be sourced in himself. This idea is of God and must be sourced in God.[3]

Finally, once Descartes has established the existence of God on the basis of his idea of him—God being more perfect than Descartes—he has good reason to be certain about clear and distinct ideas being true, and can build on this.[4] From here he proceeds to astronomy—though he does not publish this work—and then to the nature of fire. The fact that fire can sometimes produce heat and no light and vice versa, leads him into an inquiry of fire in the human heart. He describes this in great detail in part five. He concludes his work by setting out some principles for continuing his work after his death.


Evaluating Descartes one is tempted simply to throw one’s hands in the air and say “how naïve!” But it is important to understand Descartes in his social setting. It is important to see that while Descartes is typically talked about as the first modern, he was not himself modern. He was remarkably ancient in his epistemological convictions. He treatment of reason and perception for instance follows typically Platonic and Aristotelian judgments, but with the caveat of being more inclined to see error.[5] Further, Descartes thinks that man is vegetative and sensitive on account of God kindling “in the man’s heart one of those fires without light.”[6] It is really unfair to judge Descartes more harshly for his errors that come from his social context than we do others for their errors with the same source. In one sense, Descartes is not modern.

And yet, in another Descartes is the cardinal modern. Descartes seems to begin modernity in two related ways. First, Descartes is really concerned with difference in belief. There are historical reasons for this concern coming to the foreground at this particular moment, but the important point is that it continues to today. Negotiating difference of belief is the principle cause of the entire epistemic turn. Second, Descartes seems to be the first to flip the priority of epistemology and metaphysics.[7] In other words, Descartes at least makes methodological claims to start with epistemology rather than starting with faith seeking understanding. This is a massive shift in method that gets taken up with greater consistency by later philosophers to devastating effect on religious belief.

[1] In an Aristotelian sense, or “nature.

[2] For instance, he wonders in Meditations how we recognize wax as wax when its properties are altered through melting. He notes that bare perception would be confused, but that reason still recognizes it.

[3] This is obviously a very insufficient summary of the argument due to space limitations. The key moves are 1) ideas of things more perfect than Descartes cannot come from nowhere, and 2) ideas that exist clearly and distinctly must be true. It should be obvious that Descartes’ “foundation” relies on a massive set of assumptions about the nature of reason and reality and their relation.

[4] He says, “[W]e should never allow ourselves to be persuaded except by the evidence of our reason.” René Descartes, Discourse on Method, translated by Donald A. Cress. Indianapolis: Hackett Publishing Company, 1998.

[5] I have written a paper comparing Descartes and Aristotle’s accounts of error. They are remarkable for their similarity even though Aristotle famously says that sense perception cannot err in what is proper to it and Descartes doubts it all.

[6] Discourse, 26.

[7] Interestingly, there are two senses in which Descartes seems to be contradictory on this point. First, he claims not to have abandoned his religious beliefs. But later he talks of abandoning all beliefs. I take it that Descartes is simply deceitful about always holding to his religious beliefs; this is inconsistent with his stated methodology. He would have reason to be deceitful, something he explicitly admits in part six. But second, he is inconsistent even with his methodological claims since he does have some metaphysical assumptions that he cannot rid himself of. Later philosophers, like Hume, more consistently adopt his methodological claims without his metaphysical assumptions.


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