Lecture Notes

Lecture Notes: September 17

Distinction between knowledge and belief:

Consider two people in the Middle Ages
Person A: I know that the sun revolves around the earth vs
Person B: I believe that the sun revolves around the earth
What happens when we find out that the earth revolves around the sun?
change knowledge claim. Person A recants.
don't change belief claim. Person B says that he still believed it, even though it was false
You can't have false knowledge, but you can have a false belief.
even if we don't use terms exactly this way, we will for now
it doesn't matter what words we use

Q: What are some things that you know? Collect list.

Which could never be false?
necessary vs contingent
necessary truths could never be false
contingent truths could have been different

Reading through Meditation I

3 arguments for doubt:

1) Illusion.
What remains? Close objects. Own body.

After "from the senses or through the senses" (18)
Epistemology: What do we know and how do we know it?
Possible answers:
1) from senses only
but math, and 'all bachelors are unmarried' aren't sensory
Empiricism: all knowledge comes from the senses (a posteriori)
Locke, Berkeley, Hume
2) from reason
Rationalism: some knowledge is based in reason (some knowledge is a priori)
Descartes, Spinoza, Leibniz

2) Dream.
Can you dream of something that doesn't exist?
What could you know if you were dreaming?
the objects in your dream exist?
some objects exist?
2+2=4
What's left? Universals. Simples. (Building blocks: color, shape, quantity, place, time) Math.

What do you know most surely? Could God make it false?

3) Demon.
Does Descartes think there really is a demon? Why does he posit it?
Does this put mathematical knowledge in doubt?
What's left? nothing

Related to demon deceiver) Brain in a vat; the Matrix
but these presume a background physical world
the demon deciever can exist without the material world

Descartes' list of the objects of knowledge:

Class I: sensory nature of specific physical objects
Class II: Existence of specific physical objects, the physical world
Class III: Universals, nature and existence: the building blocks of physical objects
numbers, geometrical entities
logical truths (not- (p and not-p))
analytic sentences