1. Arguments for The Existence of God Ontological Cosmological Teleological Ontological Cosmological Teleological

2. God’s Existence  Not subjective  Not unprovable in principle  Natural Theology: Knowing God through reason  Biblical Theology: Knowing God through revelation  Not subjective  Not unprovable in principle  Natural Theology: Knowing God through reason  Biblical Theology: Knowing God through revelation

3. The Ontological Argument  A priori (vs. a posteriori)  God exists by definition  If you think about the concept of God hard enough, you’ll see that he must exist  A priori (vs. a posteriori)  God exists by definition  If you think about the concept of God hard enough, you’ll see that he must exist

4. Descartes’ Version  God is a perfect being  A perfect being must contain all perfections  Existence is a perfection.  God exists.  God is a perfect being  A perfect being must contain all perfections  Existence is a perfection.  God exists.

5. Anselm’s Version  Reductio ad absurdum  Indirect proof - show that atheism leads to a contradiction, so theism must be true  Reductio ad absurdum  Indirect proof - show that atheism leads to a contradiction, so theism must be true

6. Anselm’s Version  Assume God doesn’t exist  God exists only in the mind  The Greatest Conceivable Being (GCB) exists only in the mind  But this can’t be true because there is a greater being, which exists not only in the mind but in reality as well  Assume God doesn’t exist  God exists only in the mind  The Greatest Conceivable Being (GCB) exists only in the mind  But this can’t be true because there is a greater being, which exists not only in the mind but in reality as well

7. Anselm’s Version  The GCB exists ONLY in the mind  The GCB isn’t the GCB  A is not A <-- Contradiction  Atheism leads to a contradiction  Atheism is false  It’s not true that God doesn’t exist  God exists  The GCB exists ONLY in the mind  The GCB isn’t the GCB  A is not A <-- Contradiction  Atheism leads to a contradiction  Atheism is false  It’s not true that God doesn’t exist  God exists

8. Anselm’s Version  Assume not-G.  If not-G, then GCB = not-GCB  Not-not-G  G  Assume not-G.  If not-G, then GCB = not-GCB  Not-not-G  G

9. Gaunillo’s Objection  The Greatest Conceivable Island Objection (Perfect Island, Lost Island)  Assume the GCI exists only in the mind.  If the GCI exists only in the mind, then a greater island can be imagined, which exists not only in the mind but in reality  The GCI isn’t really the GCI (contrad.)  The GCI must exist.  The Greatest Conceivable Island Objection (Perfect Island, Lost Island)  Assume the GCI exists only in the mind.  If the GCI exists only in the mind, then a greater island can be imagined, which exists not only in the mind but in reality  The GCI isn’t really the GCI (contrad.)  The GCI must exist.

10. Gaunillo’s Objection  Anselm: My argument doesn’t work for the greatest conceivable kind of type of being, just the greatest conceivable being in general.  Once the limiting, imperfect particulars of the island are eliminated, the Island starts to look like God.  Anselm: My argument doesn’t work for the greatest conceivable kind of type of being, just the greatest conceivable being in general.  Once the limiting, imperfect particulars of the island are eliminated, the Island starts to look like God.

11. Kant’s Objection  Existence isn’t a property (real predicate)  The concept of a real $100 is the same as an imaginary $100; it’s just that one is instantiated.  Existence applies to a thing and it’s properties together; it is not itself a property.  Existence isn’t a property (real predicate)  The concept of a real $100 is the same as an imaginary $100; it’s just that one is instantiated.  Existence applies to a thing and it’s properties together; it is not itself a property.

12. Malcolm’s Modal Version  God is a necessary being.  If God’s existence is possible, then it’s actual.  God’s existence is possible.  God must exist.  Objection: Maybe God’s existence isn’t possible  God is a necessary being.  If God’s existence is possible, then it’s actual.  God’s existence is possible.  God must exist.  Objection: Maybe God’s existence isn’t possible

13. Other Objections  God doesn’t’ exist in the mind.  Exist “in the mind” equivocates on the term “exists.”  The terms “greater” and “greatest” are vague, value-laden or assume a Platonic metaphysics with degrees of reality.  Which is greater Jupiter or the DNA molecule?  God doesn’t’ exist in the mind.  Exist “in the mind” equivocates on the term “exists.”  The terms “greater” and “greatest” are vague, value-laden or assume a Platonic metaphysics with degrees of reality.  Which is greater Jupiter or the DNA molecule?