Rene Descartes · Philosophy
In the depths of total doubt, Descartes finds the one truth no deceiver can take from him: that while he is thinking, he exists. The cogito becomes the first certainty and the foundation of his philosophy.
Having doubted everything - the senses, the world, mathematics, all of it - Descartes seems to have reached total darkness. The evil demon might be deceiving him about absolutely everything. And yet, at this very moment, a single point of light appears. Suppose the demon is deceiving me about everything. Even so, I must exist in order to be deceived. The demon can make me believe falsely that I have a body, that there is a world, that 2 + 3 = 5 - but he cannot make me believe falsely that I exist, because the very fact that I am being deceived, that I am thinking, that I am doubting, proves that there is an ‘I’ doing it. “Let him deceive me as much as he can,” Descartes writes, “he will never bring it about that I am nothing so long as I think that I am something.” Here, at last, is a belief that survives the most radical doubt: I exist, at least as a thinking thing, whenever I am thinking. This is the famous cogito.
It is important to be precise about what the cogito establishes and what it does not. It establishes that I exist - but only, for now, as a thinking thing. Descartes cannot yet be sure he has a body, since the body is part of the doubted external world; the demon might be faking his arms, legs, and brain. What he cannot doubt is that he is something that thinks: that doubts, understands, affirms, denies, wills, imagines, and senses (in the sense of seeming to sense). “I am, then, in the strict sense only a thing that thinks,” he concludes - “a thing which doubts, understands, affirms, denies, is willing, is unwilling, and also imagines and has sensory perceptions.” The self that the cogito reveals is a mind, a thinking substance, whose existence is more certainly known than the existence of any physical thing - including its own body. This is a startling reversal of common sense: I know my own mind more surely than I know my own hands. The thinking self is the first thing certainly known, and everything else will have to be rebuilt from there.
The cogito is the ‘one firm and immovable point’ Descartes was searching for - his Archimedean point, on which he can begin to move the whole world of knowledge back into place. But notice how much work remains. So far he is certain of only one thing: that he, a thinking mind, exists right now while thinking. He is not yet entitled to the external world, to other people, to his own body, to science, or to God. All of that was swept away by the doubt and must be earned back, step by careful step, each new belief admitted only if it is as certain as the cogito. Descartes’ strategy will be to examine the cogito itself for the mark of certainty - what is it about this truth that makes it indubitable? - and then to admit any other belief that bears the same mark. He finds the mark in the cogito’s perfect clarity and distinctness: I perceive my own existence so clearly and distinctly that I cannot doubt it. So he adopts a general rule: whatever I perceive very clearly and distinctly is true. From this single secure foothold, by this single rule, he will attempt to rebuild the entire edifice of knowledge.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that Descartes found one belief that survives even the evil demon: that he exists as long as he is thinking - cogito ergo sum . Explain why this truth is immune to doubt.
Leads to Augustine of Hippo.
Begin this lesson →epoché — a humanities education that remembers you.