Descartes II

1
Descartes II

• I think, therefore I am But what am I?

2
Last time

• Last time We discussed Meditation One.
• We saw that Descartes uses the three waves of
  doubt to suspend belief in the testimony of the
  senses.
• The final argument appeared to undermine all
  belief. If we might be tricked by an evil demon,
  then it would seem that we cannot know anything
  at all.

3
Dramatic Transition

• In Meditation Two, Descartes is extremely
  disoriented by these skeptical arguments.
• He describes himself as having fallen into a
  deep whirlpool, such he does not know which way
  is up (17).

4
Is anything demon-proof?

• The three waves of doubt showed that the senses
  are not demon-proof. The demon could trick us
  into thinking that there is a hand in front of
  our face, even if this is not the case.
• Is there anything which is demon-proof?
  Descartes worries that the answer might be no.

5
Key quote

• I have persuaded myself that there is absolutely
  nothing in the world no sky, no earth, no minds,
  no bodies. Is it then the case that I too do not
  exist? But doubtless I exist, if I persuaded
  myself of something. But there is some deceiver
  or other who is supremely powerful and supremely
  sly and who is always deliberately deceiving me.
  And let him do his best at deception, he will
  never bring it about that I am nothing so long as
  I think I am something. Thus, after everything
  has been most carefully weighed, it must finally
  be established that this pronouncement I am, I
  exist is necessarily true every time I utter it
  or conceive it in my mind. (18)

6
The Cogito Argument

• This is known as the cogito argument. Why?
  Because when Descartes puts this point in Latin,
  he writes cogito, ergo sum.
• There is an old joke about Descartes He is
  sitting in a bar and the bartender asks him if he
  wants another drink. Descartes says I think
  not. And he disappears.
• Question What logically fallacy does this joke
  turn on?

7
Solipism

• You might think great, so we know that we exist
  whenever we think.
• But we would not know that anyone else exists.
  Thus it seems like we might end up with
  solipsism.
• Solipsism I cannot have knowledge of anything
  outside my own mind. (Latin solus, alone
  ipse, self)

8
Foundationalism

• But Descartes does not want to stop there. He
  wants to rebuild all of human knowledge on top of
  this certain truth.
• Foundationalism all justified beliefs are either
  (a) self-evident or (b) derivable from
  self-evident truths by the rules of logical
  entailment.

9
The Cogito and the Skeptical Infinite Regress
Problem

• Notice that the cogito puts an end to Sextus
  infinite regress problem.
• It is a self-justifying belief. Thus it can be
  the starting point for the entire series of
  beliefs.
• Question How is this going to work? Suppose
  that the cogito is true. What follows from it?
  How is he going to rebuild all of human knowledge
  upon it?

10
I am. what?

• It is nice to know that we must exist if we are
  thinking.
• But what are we? What are our essential
  properties?
• Essential properties those qualities which we
  cannot lose and remain the same thing.

11
Am we essentially our bodies?

• Can we lose our body and remain ourselves?
• It seems that the evil demon hypothesis shows
  that we are. We would think, even if we there is
  nothing in the physical world.
• So our physical bodies can (for all we know) be
  separated from ourselves.

12
Are we essentially our minds?

• It seems that the answer is yes. Because we can
  separate every property from ourselves, except
  for thinking.
• What about thinking? Here I make my discovery
  thought exists it alone cannot be separated from
  me. I am I exist this is certain I am
  therefore nothing but a thinking thing that is,
  a mind, or intellect, or understanding, or
  reason (19).

13
Sum res cogitans

• So Descartes takes himself to have discovered
  that he is a res cogitans (a thing that
  thinks).
• Notice that Descartes is taking a stance on the
  mind-body problem! He is saying that we are not
  identical to our bodies (since it seems possible
  to exist without them).

14
Sum res cogitans

• Question Does Descartes really know that he is
  only a thinking thing? What if he is actually
  identical to his body, and he merely thinks that
  he could exist without it?
• Descartes recognizes that he is not yet in a
  position to prove that dualism is true. This
  will have to wait until the Sixth Meditation.

15
Metaphysics vs. Epistemology

• So there are two main projects in the
  Meditations these have shaped all of modern
  philosophy.
• Epistemology Foundationalism
• Metaphysics Mind-Body Dualism