3.1.3 The intuition and deduction thesis Flashcards
rationalism vs empiricism
define both + what is this debate about?
empiricism: all a priori knolwdge is of analytic truths ie. there is no synthetic a priori knowledge
rationalism: not all a priori knowledge is of analytic truths ie. there are some synthetic truths that can be known a priori using rational intuition and deduction
rationalism vs empiricism
+ what is this debate about?
Most synthetic truths are known a posteriori, but the question is whether that relationship holds true all the time or just sometimes, rationalism says the latter. That there is at least one synthetic truth that can be known a priori using out rational intuition (and using deduction.)
what is an ‘intuition’
the ability to know something is true just by thinking about it
what is a ‘deduction’
a method of deribing true propositions from other true propositions
Descartes arguments are deductive arguments.
This means that if the premise are true, the conclusion MUST BE true
ie . P1) If A is true, B is true
P2) A is true
C1) Therefore, B is true
What three synthetic truths does Descartes attempt to prove using rational intuition and deducion?
and how does this support the rationalist claim
- I exist
- God exists
- The external world exists
descartes arguments for this are purely a priori; supports ratonalism claim that some synthetic truths can be known a priori
What does Descaryes do before establing what he can know (to be true)?
To achieve knowing what is true, he has to decided to first avoid believing anything that is not ‘completely certain and indubitable’.
What are Descartes’ 3 waves of doubt?
1) Illusion (I can doubt my sense experience as it has decieved me in the past eg: pencil in water)
2) Dreaming (I might think I’m awake when I’m actually dreaming)
but if I am dreaming there are still basic ideas that are common to both dreams and reality. For example, that “1+1=2” – can this be doubted?
3) YES - Deception (An evil demon may be controlling my entire experience, making me think I’m correctly adding 1 and 1 when I’m not.)
What is the conclusion of Descartes 3 waves of doubt?
So, basically anything I think I know can be doubted – an evil demon may be controlling my perception and making me have nothing but false beliefs. The evil demon scenario could be true, and there is no way I would be able to tell the difference. So, the possibility of the evil demon scenario casts doubt on everything I know.
= GLOBAL SCEPTICISM
what is global scepticism
an extreme position of doubt
Explain the COGITO argument
- Even if an evil demon is decieving me, he can never bring about that I am nothing while I think I am something
- because you cannot doubt you exist since doubting is a form of thinking which you can only do if you exist
- ergo cogito ergo ; therefor i think therefore, I am
Where does Descartes get the notion of ‘clear and distinct’ ideas from?
Upon reflection, Descartes realises his certainty in the cogito relies on how the idea presents itself in his mind.
define ‘clear’
clear and distinct ideas
present and accessible to the attentive mind
define ‘distinct’
clear and distinct ideas
it is clear and so sharply seperated from all other ideas that every part of it is clear
What is the ‘natural light’
Natural light is our ability to know that clear and distinct ideas are true. So for Descartes our rational intuition is the natural light.
‘Things that are revalved by the natural light-eg cogito- are not open to any doubt’
Descartes connects c+d ideas to what he calls the ‘natural light’
Empiricst response to the cogito
demon
What does it mean to say ‘I exist’ or ‘I think’. Descartes claims that he is a thinking thing, that he is the same thing from one thought to another. The demon could be decieving him that he is a persisting thing when in fact he is not; only a succession of thoughts.
Hume specific response to cogito
- He don’t experience a continuing mental substance over time we only experience a continually changing array of thoughts and feelings. So there is no basis for saying that there is a thing that thinks
- Descartes confuses similarity with identity
- confused our experience of the similarity of our thoughts and feelings from one moment to the next with the idea that there is one idenitical thing persisting through such thoughts to which they belong.
queery about clear and distinct ideas
it seems unclear in what sense ‘clear and distinct’ ideas are ‘indubitablle’. Simply saying that ‘I can doubt it so it must be true’ is not strong enough for the argument to persist when a persons ability to doubt something may just be a psychological fact about them–> becomes subjective.
How does Descartes prove God’s existence (3)
- cosmological
- ontological
- trademark
trademark argument
What are the three possible sources of ideas according to Descartes
- they are innate
- they are from the outside
- they have been invented by me
Trademark argument [formally stated]
P1) I have the concept of God
P2) My concept of God is the concept of something infinite and perfect
P3) But I am a finite and imperfect being (finite reality)
P4) The cause of an effect must have at least as much reality as the effect
C1) So, the cause of my concept of God must have as much reality as what the concept is about
C2) So, the cause of my idea of God must have as much reality as an infinite and perfect being (i.e. must have infinite reality)
C3) So, God exists
What principle does Descartes Trademark argument rely on
what is it + example
‘causal adequancy principle’:The cause of an effect must have at least as much reality as the effect
An example that perhaps illustrates this is getting punched by a ghost: This wouldn’t leave a physical bruise because the effect (physical reality) would have more reality than the cause (non-physical reality).
Why is the trademark argument called that
This argument is called the ‘trademark’ argument because Descartes argues that concept of God (premise 1) is like an innate ‘trademark’ placed in our minds.
What is the empiricst response to the trademark argument?
They reject both parts of it
1. That the idea of God is innate (becuase God put it there and therfore didn’t come from us)
2. that we can prove the existence of God using rational intuition (causal adequacy principle)
Explain the empiricist critique of the trademark argument that the concept of God CAN be created in our own minds
Hume rejects the claim that the trademark argument makes that the concept of God cannot be created by our own minds.
- argues that we can form the concept of God by starting from ideas of finitude and extending them beyond all limits
- since Descartes’ rational intuition revealed it must not have come from himself yet clearly that could have been the case, thus this critique undermines his method
not a fan of this one
Explain the empiricist critique of the trademark argument that we can prove the existence of God using rational intution
this critique attacks the causal adaquacy principle
- there is no contradiction that results from denying the causal adaqucy principle
- therefore it is a matter of fact which can only be proven a posteriori
- so Descartes’ argument is not ALL a priori so fails to establish rationalism
Descartes’ ontological argument
P1) I have the idea of God
P2) The idea of God is the idea of a supremely perfect being
P3) A supremely perfect being does not lack any perfection
P4) Existence is a perfection
C) Therefore, God exists
not a fan
How can Hume’s fork be used to argue against Descartes ontological argument
‘God exists’ can be denied w/o contradiction
therefore is matter of fact
can only be proven a posteriori
so his theory is not fully a priori
not a fan because the whole point of this IS to show that somethign synthetic (a matter of fact) can be proven a priori- is what descartes could respond with acc LACE
What does Descartes say about our perception of physical objects
He argues that we cannot know from perception that physical objects exist
while we can know that we have sensory experiences, those experiences don’t give us the knowledge that their causes are physical obejcts
if perception doesn’t show that physical objects exist in order to prove that they do, we must do what 4 things
- We need to understand our concept of a phsyical object- what is it that we think exists
- We need to show that this is a coherent concept not something contradictory like a round square
- we need to show that it is possible that physical objects exist
- that they do exist
How does Descartes deal with understanding the concept of physical objects and showing that they are a coherent concept
wax argument
1and2
wax argument
P1) When I melt a piece of wax, it loses all of its original sensory qualities (feel shape smell etc)
P2) Yet I believe it is the same wax
C1) Therefore, what I think of as the wax is not its sensory qualities
P3) What I think is the wax is what remains through the changes of it sensory qualities
P4) This is a body, something that is body, somehting that is extended and changeable
P5) I know that wax can undergo far more possible changes including changes in its extention than i can imagine
C2) Therefore my concept of the wax as extended and changeable does not derive from my imagination (and therefore it does not derive from perceptual experience)
C3) Therefore, I comprehend the wax as what it is (as opposed to its sensory qualities) by my mind alone
C4) Only this thought of the wax and not the perceptual experinece of it is clear and distinct.
3
Desacrtes argument for the possbility of physical objects
P1) I have a clear and distinct idea of what a physical object is
P2) (God exists and is supremely poweful )
P3) The only reason for thinking that God cannot make something is that the concept of it is contradictory
C1) Therefore God can make physical objetcs
C2) Therefore i God exists it is possible that physical obejcts exist.
How does Descartes show that because physical objects perceptions are clear and distinct and their concept is coherent AND that they are possible that this means they DO exist?
P1. I have involuntary perceptual experiences of physical objects.
P2. (These experiences are caused by some substance.)
P3. If the cause of my perceptual experiences is my own mind, my perceptual experiences are voluntary.
P4. Because I know my mind, I would know if my perceptual experiences are voluntary.
C1. Therefore, because I know that my perceptual experiences are involuntary, I know that the cause of my perceptual experiences is not my own mind.
C2. Therefore, the cause must be some substance outside me – either God or physical objects.
P5. If the cause is God, then God has created me with a very strong tendency to have a false belief (that physical objects exist) that I cannot correct.
P6. If God has created me with such a tendency, then God is a deceiver.
P7. (God is perfect by definition.)
C3. (Therefore,) God is not a deceiver.
C4. (Therefore, God did not create me with a tendency to have false beliefs that I cannot correct.)
C5. (Therefore, if God exists, I do not have such a tendency.)
C6. Therefore, if God exists, the cause of my perceptual experiences of physical objects is the existence of physical objects.
P8. (God exists.)
C7. Therefore, there is an external world of physical objects that causes our perceptual experiences.
This argument is one of the best examples of the use of rational intuition and deduction.
Empiricst response to Descartes’ proof of the external world
Descartes’ argument for the existence of physical objects depends on his arguments for the existence of God. If these fail, then he hasn’t shown that physical objects exist
critqiues of Descartes proof of the external world
Explain the objection that not everything need have a cause
- In (P2), Descartes assumes that his perceptions have a cause.
- Hume: this is not something we can know.
- The claims ‘everything has a cause’ and ‘something cannot come out of nothing’ are not analytically true. - ‘Some things do not have a cause’ is a not a contradiction in terms like ‘Some bachelors are married’ is.
- Of course, from our experience, we have good reason to think that everything has a cause, but this is still only a contingent truth; it may be false.
- So it is possible that our perceptual experiences of physical objects have no cause.
- Hume’s argument claims that we cannot know a priori that they have a cause.
- It is no contradiction (though it is very strange!) to suppose that they are uncaused.
crtique to Descartes’ overall method
The Cartesian Circle
A potential issue with Descartes’ overall approach here is that the reasoning is circular – it commits the fallacy of begging the question. This is a bit of an oversimplification but you could say Descartes’ argument is that:
1) God exists and isn’t a deceiver because I perceive it clearly and distinctly
2) and clear and distinct ideas can be trusted as true because God wouldn’t allow me to be mistaken about them.
