Heusser Philosophy 100 SG #6e

The Cartesian Method:

Proceed from self-evident axioms as starting point for deductions (synthesis)

Method 1) Accept nothing as true which is not certain (clear and distinct).

2) Analyze a problem into its parts.

3) Arrange thought from simple to complex.

4) Enumerations are full and complete and nothing is omitted.

Some terms in the Meditations: Corporeal and Mental Substance, Circular Reasoning, Certainty, Indubitable = no rational mind can doubt, Infallibility = fail-safe method

1) Certainty: Strictly Visual Distortions: A) Objects in water B) Hallucinations/Mirages

I. Some general a posteriori deceptions: 1) Plato’s Allegory of the Cave

2) Russell’s Brand New World

3) Descartes’ Dreaming Argument

No distinction exists between sleeping/awakening.

Proof that we cannot be certain of our senses:

1) It seems to me that I am now sitting in a chair.

2) I have in the past dreamed that I was sitting in a chair when it was false.

3) Thus, if I have reason to believe that I may be dreaming that I am sitting in a chair, it may be possible that it is false.

4) I can be absolutely certain of p only if I don’t have reason to believe p is false.

5) Thus, I can be absolutely certain I am sitting in a chair only if I do not have reason to doubt this.

6) Unless there are certain marks to distinguish dreaming from waking, it is not the case I have reason to think it is possible that I am dreaming.

7) But I see that there are no certain marks to distinguish these.

8) Hence, I cannot be certain that I am sitting in a chair.

II. Deceptions that jeopardize both a priori and a posteriori propositions:

4) Pollock’s Brain in a Vat

5) The Evil Deceiver: A good God would not deceive, but can we know God is good?

Evil Genius Hypothesis: There may be an omnipotent deceiver that uses all his energies to deceive me. This entails that all my former opinions are uncertain (dubitable) or false.

What can we know for sure? Cogito Ergo Sum I think, therefore I am (I am, I exist)

2) Nature: What parts do we say are necessary?

A. The Nature of Body (Corporeal Nature): 1) Has determinable shape

2) Has definable location (space & time)

3) Is perceived by 5 senses

4) Can be moved

(But powers of self-movement and sensation are foreign to the nature of body)

B. Nature of “I” (The Mental): (Not Sense Perception, Thought!) I am a thing that thinks.

I doubt, understand, affirm, deny, will, imagine, and have sense-perceptions.