his proof of the external world as examples of a priori deductions.

Question 1

proof of the external world ( a priori deduction)

Answer 1

Descartes proof attempts to show that his sensation of objects cant come from inside him and must be caused by the external world.

Descartes then continues his process of intuition and deduction to argue that because God exists, his perception can be trusted. These perceptions are of an external world of physical objects and, because Descartes can trust his perceptions, he can trust that the external world exists.

Question 2

Descartes proof

Answer 2

step 1a,b: sensations come from outside him (Descartes produces two arguments for this)

1a:
p1 the will is a part of my essence
p2 sensations are not subject to my will
conc- sensations come from outside of me

1b:
p1 my nature or essence is unextended
p2 sensations are ideas of extended things
conc- sensations come from outside of me

step 2: sensations originate from matter
p1 there are two possible sources for the origin of sensations: god or matter
p2 I have a strange natural inclination to believe they come from matter and so I have no faculty by which to correct this belief
conc- so if their origin were in god, god would be a deceiver
p3 god is not a deceiver
conc- sensation originates in the matter.

Question 3

empiricist response list of responses

Answer 3

criticism of step 1a
criticism of step 1b 
criticism of step 2
God might not exist
other ways of establishing the existence of world

Question 4

criticism of step 1a

Answer 4

perhaps sensations come from a part of me that I am not conscious. after all, dream are not subject to our will any more than our sensations are and yet they certainly come from within us

Question 5

criticism of step 1b

Answer 5

it is not obvious that an unextended thing could never produce the idea of an extended thing. Descartes is relying again on the causal principle which does not readily apply to ideas. we are clearly able to perceive the representation of extended things although our minds are unextended. perhaps we can dream them up too

Question 6

criticism of step 2

Answer 6

is everyone inclined to believe sensations come from matter? perhaps god feeds the ideas of material things directly into our minds. this is exactly the view held by Berkeley. it could be argued this is a more efficient way of arranging things since it produces the same effect without having all the bother of creating and maintaining a material world. Descartes rejects this possibility on the grounds that it would be a deception on god’s part to make us think there is a material world when there is not while giving us no means to correct this view. but or Berkeley there is no deception.

Question 7

criticism god might no exist

Answer 7

Descartes’s proof relies on the success of his earlier proofs for god’s existence which empiricists such as Hume have attacked. if these do not succeed then there is no guarantee that we are not being radically deceived and the world may be very different from the was it happens.

Question 8

criticism other ways of establishing existence of world

Answer 8

empiricist such as Locke and Russell have developed their own argument for the existence of the material world.