The Ontological Argument

1. The Ontological Argument

2. Anselm’s Definition of “God” “God” = A being “than which a greater cannot be thought”.

3. Anselm’s Argument Two big steps: Step 1: Prove that “God” at the very least, “exists in the mind”. Step 2: Prove that “God” must also “exist in reality.”

4. Step 1 1.Whatever can be understood exists in the mind. 2.The concept of God (as St. Anselm has defined it) can be understood. ------------------------------------------------------ C.Therefore, God exists in the mind.

5. Step 2 (Reductio Proof) 1.Assume (towards a contradiction) that God only exists in the mind and not in reality. 2.But then a greater being than God can be thought (namely, one that exists in reality). [From 1] 3.But God was defined as a being “than which a greater cannot be thought”. 4.So, no greater being than God can be thought. [From 3] ------------------------------------------------------- C.Contradiction (2 & 4)!!! Therefore, our original assumption must be false. God must exist in reality and not just in the mind.

6. Two ways for an argument to be bad (unsound): (i) One or more of the premises could be false. (ii) The premises could fail to support the conclusion. (There could be some gap in the reasoning.)

7. One Way of Testing Validity An argument is valid if and only if it isimpossible for the premises to be true and the conclusion false. • Validity is a “formal” property. • If an argument is valid, any argument with that form will also be valid. • So, one way of testing the validity of an argument is to test whether other arguments with the same form are all valid. • If you can find another argument with the same form that is clearly invalid, this shows that the original argument is also invalid.

8. Ben’s New Personal Ad Ben’s Ad: Philosophy grad student ISO fun-loving, comic-book-reading, arm-wrestling Checkers Grandmaster than which a greater cannot be thought. “Ben’s Dreamboat” = A fun-loving, comic-book-reading, arm-wrestling Checkers Grandmaster than which a greater cannot be thought.

9. Step 1 1.Whatever can be understood exists in the mind. 2.The concept of “Ben’s Dreamboat” can be understood. ------------------------------------------------------ C.Therefore, “Ben’s Dreamboat” exists in the mind.

10. Step 2 1.Assume (towards a contradiction) that “Ben’s Dreamboat” only exists in the mind and not in reality. 2.But then someone greater than “Ben’s Dreamboat” can be thought. [From 1] 3.But “Ben’s Dreamboat” was defined as being, among other things, someone “than which a greater cannot be thought”. 4.So, no one greater than “Ben’s Dreamboat” can be thought. [From 3] ------------------------------------------------------- C.Contradiction (2 & 4)!!!“Ben’s Dreamboat” must exist in reality and not just in the mind.

11. Further Objections Gaunilo’s objection, even if successful, only shows us that something must be wrong with Anselm’s argument, but it doesn’t show us exactly where the error lies.

12. Kant • One of the most famous objections to the Ontological Argument comes from Kant. • He objects that Anselm’s Ontological Argument treats “existence as a predicate”.

13. Ben’s Personal Ad Would it make any difference at all if I changed my personal ad to read: Philosophy grad student ISO fun-loving, banjo-playing, arm-wrestling Checkers Grandmaster who exists.

14. Blackburn’s Objection • Simon Blackburn offers his own diagnosis of the problem. • He thinks the problem has to do with the comparison (required in Part 2 of the argument) between "conception" and "reality". • The argument requires that we compare a conception of God with a real god and ask: Which one is greater? • Blackburn thinks this is an ambiguous question.

15. Blackburn’s Objection Consider the following question: “Which are heavier: real turkeys or imagined turkeys?”