Ontological Argument

• The ontological argument is an a priori argument which means it is not based on experience but logic or pure reason. It claims that if we simply try to understand what the concept of God means, we will see that it must exist.
• This argument is called a deductive argument which means that the truth of its premises logically entails the truth of its conclusion.
• P1. God is the greatest conceivable being (by definition)

  P2. It is greater to exist in reality than the mind alone

  P3. God exists in the mind

  C1. Therefore, God exists in reality
• To say that God does not exist in reality is to say that the greatest being is not the greatest being. It is self-contradictory.
• A strength of the ontological argument is that it is based on a theologically and philosophically convincing definition of God. Anselm’s definition of God is carefully designed to avoid the problem of defining something that is beyond our understanding. Anselm presents an analogy. We can’t fully look at the sun but can still see daylight. Similarly, we can’t fully know God but can at least understand that he is the greatest conceivable being.
• Applying the logic of Anselm’s argument to this island has an absurd result (reductio ad absurdum). It is greater for this island to exist in reality, so it must exist. This would work not just for an island. The greatest or supremely perfect member of every category must exist. This is sometimes called the ‘overload’ objection because it suggests that reality would be overloaded with greatest/perfect things.
• An Island by definition is land enclosed by water, so part of the concept of an Island involves a dependence on things such as an ocean or a planet to exist. So, the greatest possible Island will still be contingent, which means that it is not the case that it must exist.

  The existence of contingent beings cannot be proven a priori since their existence is not a matter of definition.

  There is nothing in the concept of the greatest being that involves dependence however, unlike the Island. So, Anselm can now argue that this is why the argument works for God but not an Island.
• Anselm’s argument only succeeds in showing that if God exists, then God exists necessarily. The ontological argument has not shown that God-the-necessary-being does exist.
• Kant says existence is not a predicate.
• Russell - the cow is brown

  the cow is brown and it exists
• Malcolm objects that if we accept God has the property of necessary existence, we cannot also claim it is possible that God does not exist. Malcolm’s argument is successful because it shows Kant contradicts himself. If God is a necessary being then God must exist. We cannot coherently say God must exist but it is possible that God does not exist
• Anselm’s argument in its strongest form:

  A being greater than which cannot be conceived must be one whose nonexistence is impossible.
• Kant’s illustration was 100 thalers (coins). Imagine you have 100 thalers in your mind as a mere concept. Then imagine you also have 100 thalers in existence, not only in the mind. You have two cases of 100 thalers, one which exists in reality and the other which only exists in your mind.
•  Being only in the mind doesn’t make the concept somehow less of a complete description of what 100 thalers is. So, existence is not part of the definition of a thing. It is not a predicate or property of the definition of a thing.
• Malcolm criticised Kant. He made the same mistake Gaunilo’s lost island argument made, which was to think we could test the logic of the ontological argument through application to contingent things, such as islands or thalers.
• necessary existence is a predicate.