Ren

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René Descartes
1596-1650 The father of modern Western
philosophy and the epistemological turn
Methodological doubt, his dreaming argument and
the evil demon argument, compared to Zhuangzi

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• Cogito ergo sum (Latin "I think, therefore I
  am")
• 1. What does he mean by "think"? thinking,
  doubting, feeling, sensing, willing, imagining,
  remembering, ...
• 2. What does he mean by "I"? A thinking being.
  Not yet include the body.
• 3. Can the dreaming argument or evil demon
  argument apply to the cogito? No.
• 4. Does it prove that he exists when he is not
  thinking, such as when he is sleeping? No.
• 5. Can I doubt my own existence? According to
  Descartes Yes -- as a mental activity, but no --
  you cannot doubt it without falling into
  contradiction. Just like "can I get 3 from 22?"
• 6. Is Descartes proving that others do not
  exist? Is he saying that only he exists? No.
• 7. What is the difference between the cogito and
  logical rules, such as A is A? This is D's
  first existential judgment.
• 8. Why is the cogito so important? It serves
  also as a proof for the reliability of reason,
  and the clarity and distinctness criteria of
  truth.

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• Is the Cogito a valid argument?
• ? Hintikka It is either question begging or
  invalid
• ? Hume We never perceive the self, only
  bundle of perceptions
• ? Gilbert Ryle The Cartesian self is a ghost
  in the machine
• ? Wittgenstein I am not part of my world, it
  is the limit of my world
• ? Buddhism The false notion of I is the
  source of our own suffering

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• The existence of God
• 1. The Ontological Argument (an a priori
  argument)
• God is by definition perfect
• Existence is a perfection
• God must exist
• 2. The Trademark Argument (an a posteriori
  argument)
• (1) Everything has a cause. Nothing comes from
  nothing.
• (2) The cause must contain no less reality than
  its effect (the principle of causal adequacy).
• (3) I have the idea of an infinitely perfect
  Being.
• (4) I am imperfect, so I cannot be the cause of
  the idea. Only God (a perfect being) can cause
  such an idea in me.
• (5) Therefore, God exists

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• Is the Ontological Argument convincing?
• God is by definition perfect
• Existence is a perfection
• God must exist
• (1) Can I similarly define a perfect dog or
  island, an exista-unicorn, an exista-round-square,
  etc. and hence prove their existence?
• (2) Kant existence is not a property. It is an
  instantiation.
• -- Existence is about "is there any X?"
• -- Property is about "what is X?"

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• Is the Trademark Argument convincing?
• (1) Everything has a cause. Nothing comes from
  nothing.
• -- Coming from nothing does not mean caused by
  nothing.
• -- If so, where does God come from?
• -- Why cannot the universe be always there?
• -- Modern physics the universe may come from
  nothing
• (2) The cause contain no less reality than its
  effect (the principle of causal adequacy).
• -- but a murderer does not have to be as dead as
  his victim
• -- a cause only needs to be sufficient for the
  effect it does not have to pre-contain the
  effect.

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• (3) I have the idea of an infinitely perfect
  Being.
• -- we have a concept of a perfect being, but not
  an idea (image) of it.
• (4) I am imperfect, so I cannot be the cause of
  the idea. Only God (a perfect being) can cause
  such an idea in me.
• -- why cannot the concept come from our ability
  to reason?
• (5) Therefore, God exists
• -- ?

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• Descartes Main Line of Reasoning
• Methodic doubt sense experience is not reliable
• Cogito (1) I (as a thinking being) exist.
• (2) Reason is the only reliable faculty
  for knowledge. Clarity and distinctness are the
  criteria for knowledge.
• The Existence of God God is not a systematic
  deceiver.
• The existence of the physical world.

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• Daily One-minute Paper
• 1. What is the big point you learned in class
  today?
• 2. What is the main, unanswered question you
  leave class with today?