Rene descartes quotes i think therefore i am

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Cogito ergo sum

This article explores its meaning, significance, and how it altered the course of philosophy forever. Even with a less ambiguous translation, however, we might still wonder why this statement is so celebrated. But Descartes was not without reason: in his work as a mathematician, he worried that if the foundations of knowledge were not completely solid, anything built upon them would inevitably collapse.

If we want to establish real, irrefutable certainty about reality, Descartes thinks, we must be strict in our approach. He thus decides that if there is reason to doubt the truth of something — no matter how slim the doubt — then it should be discarded as false. Descartes asserts that most if not all of his opinions are based upon his experiences of the world through his five senses.

His senses, however, are not always trustworthy — when he dreams or hallucinates, for instance, his experiences do not align to reality. How often has it happened to me that in the night I dreamt that I found myself in this particular place, that I was dressed and seated near the fire, whilst in reality I was lying undressed in bed! At this moment it does indeed seem to me that it is with eyes awake that I am looking at this paper; that this head which I move is not asleep, that it is deliberately and of set purpose that I extend my hand and perceive it; what happens in sleep does not appear so clear nor so distinct as does all this.

But in thinking over this I remind myself that on many occasions I have in sleep been deceived by similar illusions, and in dwelling carefully on this reflection I see so manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep that I am lost in astonishment Have you ever hallucinated your socks off?

Have you ever sworn to have witnessed something when someone else swears to have witnessed something else? As Descartes so eloquently describes, when our perception of the world fails us, it can be jarring. Are the dots above black or white?