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  • How do you know you're real?

  • It's an obvious question until you try to answer it,

  • but let's take it seriously.

  • How do you really know you exist?

  • In his "Meditations on First Philosophy,"

  • René Descartes tried to answer that very question,

  • demolishing all his preconceived notions and opinions

  • to begin again from the foundations.

  • All his knowledge had come from his sensory perceptions of the world.

  • Same as you, right?

  • You know you're watching this video with your eyes, hearing it with your ears.

  • Your senses show you the world as it is.

  • They aren't deceiving you, but sometimes they do.

  • You might mistake a person far away for someone else,

  • or you're sure you're about to catch a flyball,

  • and it hits the ground in front of you.

  • But come on, right here and now,

  • you know what's right in front of you is real.

  • Your eyes, your hands, your body: that's you.

  • Only crazy people would deny that, and you know you're not crazy.

  • Anyone who'd doubt that must be dreaming.

  • Oh no, what if you're dreaming?

  • Dreams feel real.

  • You can believe you're swimming, flying

  • or fighting off monsters with your bare hands,

  • when your real body is lying in bed.

  • No, no, no.

  • When you're awake, you know you're awake.

  • Ah! But when you aren't, you don't know you aren't,

  • so you can't prove you aren't dreaming.

  • Maybe the body you perceive yourself to have isn't really there.

  • Maybe all of reality, even its abstract concepts,

  • like time, shape, color and number are false,

  • all just deceptions concocted

  • by an evil genius!

  • No, seriously.

  • Descartes asks if you can disprove the idea that an evil genius demon

  • has tricked you into believing reality is real.

  • Perhaps this diabolical deceiver has dupedyou.

  • The world, your perceptions of it, your very body.

  • You can't disprove that they're all just made up,

  • and how could you exist without them?

  • You couldn't! So, you don't.

  • Life is but a dream,

  • and I bet you aren't row, row, rowing the boat merrilyat all, are you?

  • No, you're rowing it wearily

  • like the duped, nonexistent doof you are/aren't.

  • Do you find that convincing?

  • Are you persuaded?

  • If you aren't, good; if you are, even better,

  • because by being persuaded,

  • you would prove that you're a persuaded being.

  • You can't be nothing if you think you're something,

  • even if you think that something is nothing

  • because no matter what you think, you're a thinking thing,

  • or as Descartes put it, "I think, therefore I am."

  • and so are you, really.

How do you know you're real?

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B1 INT US TED-Ed descartes aren rowing dreaming exist

【TED-Ed】How do you know you exist? - James Zucker

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