Transcript Descartes, and against Descartes

O.A. so far..
• Anselm – from faith, the fool, 2 part argument
• God as TTWNGCBT but existing in reality is greater. Reduction ad absurdum
• God must necessarily exist. If only “possible” existence, then not maximal
being, as not existing is inferior to existing. Absurd.
• Gaunilo – 2 part challenge
• Descartes – 2 part formulation of the OA
DR AQUINAS
1. DEFINITION Argument
• Aquinas’ second point, is that the human mind cannot have a certain and
correct concept of God – so humans cannot prove that God exists from
their mere idea of God. Only if our definition of God is correct, can we say
that God exists. (“To know that a man is approaching is not the same as to
know that Peter is approaching”.)
• So a priori arguments to prove God’s existence fail, as we cannot correctly
define God. Eg the fool may have a different understanding of God. The
existence of God cannot be self-evident to us (we cannot conclude
anything with certainty about God).
2. CAN’T DERIVE REALITY FROM CONCEPT
• Anselm only shows that the concept of existence is inseparable from the
concept of God. Whether such a concept exists in reality, is in fact a
different question.
• To prove that it is impossible to think of God as not existing, is not to prove
the connection exists in reality. That is a synthetic judgement.
Recap Descartes arguments – 2 parts
• Clear and distinct idea of God
• “Necessary existence” part of concept of God
• Like triangles
• Like mountains/ valleys
Intuition reflects reality.
• Existence as a perfection
• God as supremely perfect being
• Cannot lack existence: or any existing things would be more perfect
Anselm does NOT really see existence as a perfection – this is Descartes own
formulation.
Descartes, and against
Descartes
Hume
Kant
Objections to the
O.A. take 3 forms:
R Arguments against
deriving reality from a
concept
E Arguments against
existence as a perfection
D Arguments concerning
the possibility of defining of
God
Aquinas
Definition
argument
Can’t derive
Reality from logic
Analytic vs. Synthetic (types of proposition)
A priori vs. A posteriori (types of knowledge
(1) All a posteriori judgments are
synthetic – you need to see what the
case is in th real world. So analytic a
posteriori judgment is not a real
possibility.
(2) Analytic a priori judgments are purely
formal: definitional tautologies.
(3) Synthetic a posteriori judgments are
empirical and rest upon sense experience.
(4) Synthetic a priori judgments are
characterized by (a) an a priori element
which is universal and necessary as well
as (b) an empirical element which
applies to the world. Thus there is in the
"synthetic a priori" that which is not
derived from experience, but yet applies to
experience.
Analytic
Synthetic
(predicate contained in (predicate not
subject)
contained in subject)
Bachelors are unmarried Fire is hot
A priori
Analytic A priori
Synthetic A priori
(necessary and
universal)
A posteriori
(knowledge after
experience)
Analytic A posteriori Synthetic A
posteriori
“God exists” – what kind of
statement is this?
Hume
1. CAN’T DERIVE REALITY FROM CONCEPT (like Aquinas)
• If we can conceive of something as existing, we can also
conceive of it as not existing. There is no contradiction in that.
• There is no being whose non-existence is contradictory
(beings exist or don’t exist, as a matter of fact in the world).
• God’s non-existence could only be contradictory if it was an analytic truth that
God exists (ie existence is part of the concept of God).
• IS IT ANALYTIC? No. It is a matter of fact whether or not God exists (ie a synthetic
truth)
• so then God’s non-existence is possible – it is just a matter of fact which needs to
be observed, as to whether or not He exists.
• You can’t take a logical idea and make a conclusion about the
physical universe from it. This is impossible (not just a “lack of
proof of the connection” – Aquinas)
Explain Hume’s 1st
objection to
Anselm.
How is his
argument different
from Aquinas’?
Hume
1. CAN’T DERIVE REALITY FROM CONCEPT (like Aquinas)
“God does not exists” is not a self-contradictory, because it
is not analytic. As a matter of fact, God may not exist, no
matter what our concept.
DESCARTES can have 2 possible REPLIES to HUME:
1. “God exists” is analytic, because as the maximal being, it is
incoherent to deny God existence. God being God must include
existence. (STILL doesn’t prove it is so in reality!)
Also all attributes of God entail each others – to be omnipotent means
not to be dependent on anything, even for own existence: so necessary
existence is implied by all the other attributes of God.
2. Or he could agree that “God exists” is synthetic, but a priori. Our
thought reveals reality. It is a matter of fact if He exists or not, but given
the concept, we can be sure that he does. Our thought reveals reality.
What do you think
about the replies?
Do they work?
Hume 2 -RE
1. CAN’T DERIVE REALITY FROM CONCEPT (like Aquinas) “God does
not exists” is not a self-contradictory, analytic. As a matter of
fact, God may not exist, no matter what our concept.
2. EXISTENCE IS NOT A PREDICATE (Aquinas’ 2nd was the Definition
argument)
• Hume’s 2nd point, is that existence is not a predicate. Adding existence to
something, doesn’t change what that thing is.
• To reflect on something, and to reflect on it as existing, is not any
different.
• Think of a dog. Now think of a dog existing. Is it a different dog?
• So to think of God “in the mind” and to think of God “in reality” is exactly
the same thing. All we are doing, is thinking about God, not proving he
exists.
• Kant develops this objection further.
Add
existence??