Descartes

The Problem of Doubt

• For Descartes: Galileo

• Descartes lived during the time of Galileo, who demonstrated that the Earth orbited around the sun instead of the sun orbiting around the earth. When he talks about the opinions of his early adulthood being overturned, he is talking about this issue in astronomy 

Galileo

• The significance of Galileo’s discovery is often misunderstood and has been oddly politicized over the past century. It is important to realize that the debates surround Galileo were NOT primarily about science vs religion

Who Advocated the View that the Sun orbited the Earth?

• The model of astronomy advocating that the Sun orbited the Earth was developed by the secular philosopher/scientist Aristotle nearly two thousand years earlier (modified by Ptolemy in the second century AD)

• Aristotle was so widely respected in Galileo’s time that he was referred to as ‘The Master of Those Who Know’ and ‘THE Philosopher’ by medieval thinkers.

Why do people think Galileo is about science vs religion?

• Was greatly respected by Pope Urban VIII, who asked to write a book comparing the earth centered and the sun centered views of the solar system 

• His book advocated the correct view that the Earth orbited the sun and mocked traditional view. He put the Pope’s own words into the mouth of incompetent and mocked defender of the traditional view

• Was condemned by mocking the Pope 

• Mocking the Pope wasn’t a crime, so he was charged with irreligious interpretation of the solar system

The Fallout of Doubt

• Difficult for a contemp person to understand how disturbing the overturning of the traditional view of astronomy was, 2,000 year old view, endorsed by the most respected secular and religious experts. contemporary

• Casted everything into doubt, especially SCIENCE

Descartes Modern Project

• The Goal: Identify an Undoubtable Foundation for Knowledge that will ground science so that there will be no more shocking Copernican/ Galileo style revolutions ( sun centered)

• Strategy: Employ systematic doubt. Doubt everything that can be doubted. Whatever is left standing true

Problem 1

• A tremendous amount of knowledge depends upon the five sense. But, the five sense can be doubted

• Sometimes they mislead. Sometimes they are wrong about everything, as when one dreams.

• How do we know we aren’t asleep

Sleep Puzzle Solved?

• waking life has a clear and distinct nature to the experience that sleep does not

• Even in certain things will be true, such as a truths of math, geometry, simples

Greater Problems For Knowledge

• What if i’m systematically insane and keep thinking 2 + 2 = 5

• What if God were to systematically deceive me?

• What if an all powerful evil demon were systematically deceiving me?

Simple Solution to ‘God’ Problem

• God by definition is Good, and therefore would not systematically deceive. But, this is a trivial victory for our knowledge

• But, what if an all powerful trickster demon/God (Loki) were to systematically deceive? How can we know this isn’t really our situation

What’s Needed To Avoid Skepticism

• A single foundational doubtless point from which other truths could be secured

• If we can find one starting point with absolutely secure knowledge, we might be able to construct an entire system, of knowledge

Cogito ergo Sum

I think, therefore I am

• Even if I am systematically deceived, there must be come ‘I” in order to be deceived. Therefore, I must exist

Limits of the Cogito Argument 

What does it prove?

• It appears to prove that some sort of personal being “I” currently exists

What doesn’t it prove?

• It doesn’t prove I can trust my senses, my memory, that anyone else exist, that the external world exists, that my body exists, or that I existed five minutes ago

Long Lasting Results of the Cogito Argument

• Emphasis on individualism throughout modern era (since I am
  more confident about the existence of ‘I’ than anything else)

• 
  • Mind/body puzzle (A strong distinction between the
  immaterial mind/soul and material body is established since
  we are far more confident in the existence of the mental self)

• 
  • Entrenchment of doubt and skepticism in philosophy and
  academic thought. Ultimately Descartes is more effective in
  raising the Modern problem of doubting all knowledge claims
  than in resolving that doubt.

• 
  • Note the cogito seems very similar to a point made in
  Augustine’s Free Choice of the Will about the certainty of the
  self’s existence.

Development of Descartes Argument: What Happens Next

• “I” defines as ‘thinking thing’

• The sense still under deep suspicion

• Search for abstract ‘a priori’ foundation to knowledge demonstrable apart from the sense [rationalism], since the five sense are still deeply doubted

Thinking thing

• Thinking is an essence as it is the only thing that cannot be doubted

Rationalism

• Belief that reason and logic are the primary sources of knowledge, allowing for discovery of truth through innate ideas

Remaining Strategy For Descartes 

• The foundation of the ‘I’

• Attempt to prove the existence of God from abstract ‘ a prior’ premises

• Establish the general reliability of the senses
  from the good, undeceptive nature of God

• • Establish the existence of the external world
  

• • Establish the trustworthiness of science

Overarching Strategy Reviewed

• Goal: Establish an indubitable foundation for Science

• Step 1 : Prove the existence of the self

• Step 2: Prove the existence of God without using the senses

• Step 3: Establish the general reliability of the sense from the good nature of God

• Step 4: Establish the trustworthiness of science

Ontological Argument: For God’s Existence

• Premise 1: I posses an idea of a perfect being

• Premise 2: I ( nor any other imperfect being) could not be the ultimate source of that idea

• Conclusion: Therefore, the idea of a perfect being must come from a perfect being, and that perfect being must exist

Cosmological Argument

• Premise 1: I exist

• Premise 2: I am not the ultimate cause of my own existence

• Premise 3: No contingent being could be the ultimate cause of my existence 

• Conclusion: Therefore, a necessary being ( God) must be the ultimate cause of my existence 

Implications from God’s Existence

If a perfect being exists, that being must be good (by
definition of ‘perfection’, it must be morally perfect).
(Note that only the ontological argument requires
God to be perfect)
• An all-powerful morally perfect being would not let
humans be systematically deceived. Therefore, my
senses must be generally reliable.
• Therefore, the external world must exist.
• Therefore, the general methodology of science must
be reliable as it appears from our senses.

The Cartesian Circle

If we are doubt to everything, including the reliability of our own rational faculties; how could this strategy ever prove the rationality of our faculties if that is the very thing in doubt?

A Final Objection

Even if we accept each step in the argument so far, this
problem remains:
• The Cartesian Circle: if we are to doubt everything,
including the reliability of our own rational faculties; how
could this strategy ever prove the rationality of our faculties
if that is the very thing in doubt?
• Premise: My rational faculties tell me that my rational
faculties can be trusted.
• Conclusion: My rational faculties can be trusted.
• But isn’t it possible that dysfunctional faculties would tell
us the same thing? We aren’t supposed to be trusting our
rational faculties, we are supposed to be doubting them

The Madman’s Circle

• Premise: My rational faculties tell me that i’m not insane and that I’m Napoleon

• Conclusion: I am sane and i must be Napoleon

If our faculties are to be doubted, we cannot use them
to prove that are faculties are reliable. But, what else
might we use?