CARTESIAN SKEPTICISM

Rene Decartes

  • 1596-1650

  • French philosopher, mathematician, and scientist

  • Godfather of “Modern” Philosophy (early modern)

  • Started debate between epistemology and rationalism

Descartes’ Opponent

  • He’s a skeptic

  • Skeptics think we cant know anything at all

  • Some skeptics think we can know some things, but we cant know the external world is real

  • Descartes himself DOES NOT want skepticism to be true

Descartes’ Strategy

  • Figure out which of our foundational beliefs are secure (have to be true)

  • Build off of beliefs and form new ones

  • Worry that if we cant find secure foundational beliefs, all of our beliefs are doubtable

Meditations

  • Starts with story as a kid he believed a bunch of false things

  • Now that he’s grown up, he wants to make sure he doesn’t do the same thing

  • Double checks foundational beliefs to ensure he can trust all other beliefs

  • Clean slate → He assumes its false

  • Once he finds & accepts a belief he’ll use it as a foundation to build off of

Candidates for Foundational Beliefs

Our Senses

  • Senses sometimes deceive us

  • Hallucinations, optical illusions

Sense-Beliefs

  • Some sense beliefs more certain than others

  • Even if our senses are deceiving (were mistaken about the height of someone far away)

Descartes’ Dreaming Argument

  • We doubt our sense-beliefs because we are dreaming

  • Dreams seem fake, but Descartes reflects that some of his dreams are hyper-realistic

  • Even if we’ve never had a realistic dream, we cant be certain our experience s right not are not a super realistic dream

  • Stuff in our dreams are based on real life

  • We can dream about unicorns but they’re not real → Descartes thinks image of unicorns borrow from things in real life

Meditation 1

  • Demon is attacking him

  • Has a crisis then falls sleep to try again tomorrow

Meditation 2

  • Demon is deceiving you

  • Descartes himself exists (and is thinking) → foundational belief

  • He is the author of his thoughts, even if they’re made by the demon

  • For you to have thoughts/beliefs, whether they’re true of false, they still require you there to have them

  • Descartes is ASSUMING THERE IS AN EVIL DEMON for the argument

COGITO → “I think, therefore I am”

What Can Not Be Determined

  • Do we know our physical bodies exist? → Descartes: NO, cant trust senses

  • Do we know other people exist/Are they thinking → Descartes: NO, cant know if they’re thinking/doubting or they may just be illusions

  • Do we know we exist when we’re not thinking → Descartes: NO

Major Metaphysical Implications

If Descartes is right, it seems:

  • We are not our physical bodies (whether demon is real/not)

  • Maybe we occupy bodies (no evil demon)

Why this Implication?

P1: We could be mistaken about our bodies existing (by evil demon)

P2: If we equal our bodies, then we could be mistaken about ourselves existing

P3: But we can’t be deceived about us existing, at least when were thinking

C: Therefore, we can’t be equivalent to our bodies

What Are We? (According to Descartes)

According to Descartes:

  • Were thinking things

  • Maybe more, but thats kind of it.

KEY TAKEAWAYS

*WE CAN KNOW CERTAIN THINGS FROM INTELLECT/REASON ALONE*

  • No need to use senses

  • I exist as a thinking thing (fundamentally)

  • Foundational belief came about not from senses but from mind alone

  • We are not identical to our physical bodies

Objections to Meditation I & II

  • Descartes assumes thoughts require a thinker

  • Is it possible for there to be thoughts without a thinker?

  • We fundamentally exist as non-physical things

  • How does our non-physical selves interact with our physical body?

  • Descartes fully relies on logic in meditation II → demon still could be tricking

JTB

Justified True Belief

  • You have knowledge if you believe it

  • You can justify it with evidence

  • Theoretically it’s true (no evil demon)

ALL ARE TRUE = SUFFICIENT