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Descartes’ Method of Systematic Doubt


Method of Systematic Doubt

Descartes is anything but a skeptic. But in his Meditations on First Philosophy he proposes that we meditate with him, reasoning by questioning everything about which we are not completely certain. Then on the basis of a foundation that cannot be doubted, we are to rebuild our belief system, our philosophical system, using a geometric method — that is a method that deduces theorems from self-evident axioms and universally accepted definitions.

The Meditations proceed with a process of introspection. We are to cull our minds, to examine our beliefs. The fact that Descartes views this as a “meditation” appears to hint at a kind of religious obligation. Descartes isn’t examining conscience in quite the manner of St. Teresa of Avila, primarily with a mind to finding God, but rather with a view to whether his general beliefs are true. It’s an examination more like that of Socrates than St. Teresa. Yet, it is an examination of foundational beliefs in light of our uniquely human reason. For a man of some religious sensibilities, there is something fundamentally sacred about this. For a pure humanist, it could also be viewed as a uniquely important human responsibility.

In his first meditation, Descartes finds reasons to question the general knowledge that we take for granted. The knowledge coming from our sense experience is anything but indubitable. The senses often deceive us. Don’t those far away look small, when in reality we know them to be be large. Doesn’t a stick in the water looked curved, though it remains straight? Further, people in unusual situations experience false sensory information. Those in a desert for days will hallucinate and see mirages of water that don’t exist. Those who have lost their limbs often still recount pain or itching from them, though they are no longer there. Descartes uses these and other arguments to underline that senses are often a poor guide to knowledge. Further, though, people often have dreams from which they awake, surprised that they had been dreaming. This calls to mind the famous statement of Zhaungzi, which Descartes shows no familiarity with but that serves to underline his point:

Once upon a time, I, Chuang Chou, dreamt I was a butterfly, fluttering hither and thither, a veritable butterfly, enjoying itself to the full of its bent, and not knowing it was Chuang Chou. Suddenly I awoke, and came to myself, the veritable Chuang Chou. Now I do not know whether it was then I dreamt I was a butterfly, or whether I am now a butterfly dreaming I am a man.

Zhaungzi, the Ancient Taoist, expressed a similar concern about certainty to that of Descartes. But Descartes goes even further. He asks to imagine that there is an evil deceiver, a demon that is creator of the world who has tricked us into thinking things are true that are not. Descartes point is not that it is likely that there is such a deceiver. It is merely that it is conceivable that there is. We have some reason for doubt. This is Descartes’ final argument that the senses and our normal common sense should not serve as a foundation for our worldview. There is amble evidence that the senses can and often do deceive us. There is reason to believe that we could be confused about our most basic beliefs. What is it that we can know with absolute certainty?

Cogito Ero Sum

Descartes’ answer is that our individual existence is the one foundational truth that we cannot reasonably doubt. His argument is that even if there were an evil deceiver and each thought we as individuals have is incorrect, the fact that we as individuals are thinking any thought means that we as individuals exist. Cogito ergo sum. I think therefore I am. Even if we are mistaken about everything we think, we have indubitable proof that we as individuals exist — namely that we are thinking.

Proceed to the next section.


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