1. 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

2. 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.

3. 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.

4. Descartes, and against Descartes
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
Hume
Kant

5. Aquinas
Can’t derive Reality from logic
Definition argument

6. “God exists” – what kind of statement is this?
Analytic vs. Synthetic (types of proposition)
A priori vs. A posteriori (types of knowledge
Analytic
(predicate contained in subject)
Bachelors are unmarried
Synthetic
(predicate not contained in subject)
Fire is hot
A priori
(necessary and universal)
Analytic A priori
Synthetic A priori
A posteriori
(knowledge after experience)
Analytic A posteriori
Synthetic A posteriori
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.
“God exists” – what kind of statement is this?

7. Hume 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’?

8. Hume 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?

9. Hume 2 -RE
Add existence??
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.
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.