PHL 205 Descartes Final

Why does Descartes doubt all of his empirical beliefs (belief in an external world and belief that he has a body)?

• Descartes uses dreams → concludes that there is no difference between the sensations that we experience when we are awake and the experiences we have while we are asleep 

• Any test that could theoretically distinguish between a dream and reality could realistically be a part of the dream, and one would have to theoretically step away from their mind to distinguish what is part of the external world and what sense perceptions are not representative of reality.

Why does Descartes doubt the certainty of arithmetic and geometry?

• Descartes believes that math and geometry are primitive notions, and can be understood regardless of experience → we do not need experience from an external world to confirm these ideas, so even if the external world was an illusion: math and geometry would remain valid

• Doubts this because God may be using his power to fool Descartes 

• Doubts this as well because God may not exist, and Descartes mind is the culmination of meaningless coincidences that have caused his mind’s existence → in this case, Descartes has no reason to believe that his primitive notions are representative of some greater and innate knowledge of the world as it actually exist

Hyperbolic doubt

• Descartes uses hyperbolic doubt to examine all of his prior beliefs because he’s trying to develop a new system of philosophy (unlike Scholastic philosophy) that aligns with mechanist physics

• If there is any possibility that a belief is uncertain, it must be treated as false 

The cogito argument

• “I think therefore I am” 

• In order to be deceived, as Descartes considered in the above bullets, Descartes must exist to some degree because something that does not exist cannot be deceived through thoughts and perceptions. 

• Thought is a sufficient condition for existence 

• The cogito proves that Descartes must exist, regardless of whether or not the manner in which his mind perceives existence is representative of a mind independent world and whether or not his primitive notions provide valid insight into how the world functions. 

• Descartes believes that the cogito argument withstands his standard of hyperbolic doubt, and wants to use the cogito as an axiom to prove further truths

Clear and distinct perceptions

• Easily accessible, lucid to the mind that is representative of a concept/ thing → types of thoughts the mind can have 

• Mathematics are examples of clear and distinct perceptions → can only be treated as truth functional after the proof of a benevolent God (only God could be falsifying our clear and distinct perceptions)

Why does Descartes want to prove that God exists?

• Descartes tries to prove that God exists and will never deceive him because then Descartes can use his clear and distinct perceptions when making judgements and about his mind and the external world (only God’s existence can confirm that Descartes’ clear and distinct perceptions are representative of greater universal truths) 

• Begins by examining the idea of God, investigates if any part of the idea of God could have originated from something independent of Descartes 

• An idea’s level of objective reality (amount of perfection represented by the idea of the object) is its object’s formal reality (how perfect the object is in actuality) → only ideas have objective realities because only ideas have objects & the perfection of an effect cannot be greater than the perfection of its caused (based on principle of causation)

Descartes’ proof for God

1. All my ideas have a cause

2. ~The objective reality of an idea can exceed the formal reality of its cause

3. If Descartes is a finite thing, then he can be the cause of ideas with finite objective reality

4. If Descartes is a finite thing, then ~he can be the cause of ideas with infinite objective reality

5. God is infinite

6. Descartes has an idea of God

7. Descartes cannot be the cause of his idea of God

Descartes proof against God being a deceiver:

1. God is an infinite substance 

2. God’s perfection prevents him from deceiving us

3. The mind alone can grasp certain truths

4. If a being is perfect, then it has no defects

5. Deception is defective

6. The mind grasps that a being is perfect v deception is defective

7. ~God is a deceiver.

Cartesian circle

 argues that Descartes never questioned his clear and distinct perception because he justifies his proof for God because he perceives it clearly and distinctly but it is his proof that should be establishing whether or not he can perceive things clearly and distinctly.

Cartesian dualism: 

• explains the mind body problem by establishing two different substances, extended and thinking substances

• Descartes believes that the mind and the body interact through a series of nerve lapses that connect to a gland that then sends signals to the mind which cause ideas, problematic because how can an extended thing affect a non-extended thing (?) 

• The human being is the unity of a thinking and extended substance