1
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How do you know you're real?

2
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It's an obvious question
until you try to answer it,

3
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but let's take it seriously.

4
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How do you really know you exist?

5
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In his "Meditations on First Philosophy,"

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René Descartes tried to answer
that very question,

7
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demolishing all his preconceived
notions and opinions

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to begin again from the foundations.

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

10
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Same as you, right?

11
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You know you're watching this video
with your eyes, hearing it with your ears.

12
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Your senses show you the world as it is.

13
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They aren't deceiving you,
but sometimes they do.

14
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You might mistake a person
far away for someone else,

15
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or you're sure you're about
to catch a flyball,

16
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and it hits the ground in front of you.

17
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But come on, right here and now,

18
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you know what's right
in front of you is real.

19
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Your eyes, your hands,
your body: that's you.

20
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Only crazy people would deny that,
and you know you're not crazy.

21
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Anyone who'd doubt that must be dreaming.

22
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Oh no, what if you're dreaming?

23
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Dreams feel real.

24
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You can believe you're swimming, flying

25
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or fighting off monsters
with your bare hands,

26
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when your real body is lying in bed.

27
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No, no, no.

28
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When you're awake, you know you're awake.

29
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Ah! But when you aren't,
you don't know you aren't,

30
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so you can't prove you aren't dreaming.

31
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Maybe the body you perceive
yourself to have isn't really there.

32
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Maybe all of reality,
even its abstract concepts,

33
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like time, shape, color
and number are false,

34
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all just deceptions concocted

35
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by an evil genius!

36
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No, seriously.

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

38
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has tricked you into
believing reality is real.

39
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Perhaps this diabolical
deceiver has duped you.

40
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The world, your perceptions
of it, your very body.

41
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You can't disprove
that they're all just made up,

42
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and how could you exist without them?

43
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You couldn't! So, you don't.

44
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Life is but a dream,

45
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and I bet you aren't row, row,
rowing the boat merrily at all, are you?

46
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No, you're rowing it wearily

47
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like the duped, nonexistent
doof you are/aren't.

48
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Do you find that convincing?

49
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Are you persuaded?

50
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If you aren't, good;
if you are, even better,

51
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because by being persuaded,

52
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you would prove
that you're a persuaded being.

53
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You can't be nothing
if you think you're something,

54
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even if you think
that something is nothing

55
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because no matter what you think,
you're a thinking thing,

56
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or as Descartes put it,
"I think, therefore I am,"

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and so are you, really.

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(Airplane engine)