The Ontological Argument

Anselm’s Argument So the fool has to agree that the concept of something than which nothing greater can be thought exists in his understanding, since he understood what he heard and whatever is understood is in the understanding. And certainly that than which nothing greater can be thought cannot exist only in the understanding. For if it exists only in the understanding, it is possible to think of it existing also in reality, and that is greater. If that than which nothing greater can be thought exists in the understanding alone, then this thing than which nothing greater can be thought is something than which a greater can be thought. And this is clearly impossible. Therefore there can be no doubt at all that something than which a greater cannot be thought exists both in the understanding and in reality.

Anselm’s Argument 1.The greatest being conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t the greatest being conceivable is not the greatest being conceivable

Anselm’s Argument 1.The greatest being conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t the greatest being conceivable is not the greatest being conceivable The greatest being conceivable does exist in reality

Gaunilo’s Island 1.The greatest island conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t the greatest island conceivable is not the greatest being conceivable

Gaunilo’s Island 1.The greatest island conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t the greatest island conceivable is not the greatest island conceivable The greatest island conceivable does exist in reality

Gaunilo’s Island

Anselm’s Reply First Form First Form 1.The greatest conceivable X does not exist in reality 2.Something that really exists is greater than something that doesn’t the greatest conceivable X is not the greatest conceivable X A Contradiction

Anselm’s Reply Second Form Second Form 1.The X does not exist in reality 2.Something that really exists is greater than something that doesn’t the X is not the greatest conceivable being Not A Contradiction

The Fool’s Reply 1.The greatest being conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t

The Fool’s Reply 1.The greatest being conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t

The Fool’s Reply 1.The greatest being conceivable does not exist in reality 2.Something that really exists is greater than something that doesn’t

The Fool’s Reply 1.The X does not exist in reality 2.Something that really exists is more Y than something that doesn’t the X is not the most Y conceivable being

The Fool’s Reply 1.The X does not exist in reality 2.Something that really exists is more dirty than something that doesn’t the X is not the most dirty conceivable being

Descartes’s Version … whenever I choose upon any thought of the First and Supreme Being, and as it were bring out the idea of him from the treasury of my mind, I must necessarily ascribe to him all perfections … This necessity clearly ensures that, when later on I observe that existence is a perfection, I am justified in concluding that the First and Supreme Being exists.

Descartes’s Version 1.God has all the perfections 2.Existence is a perfection God exists

Descartes’s Version Kant’s Critique Being is evidently not a real predicate, that is, a conception of something which is added to the conception of some other thing. It is merely the positing of a thing, or of certain determinations in it. Logically, it is merely the copula of a judgement. The proposition, God is omnipotent, contains two conceptions, which have a certain object or content; the word is, is no additional predicate – it merely indicates the relation of the predicate to the subject. Now, if I take the subject (God) with alll its predicates (omnipotence being one), and say: God is, or There is a God, I add no new predicate to the conception of God, I merely posit or affirm the existence of the subject with all its predicates – I posit the object in relation to my conception.

Descartes’s Version Kant’s Critique 1.The attribution of real predicates defines the conception of an object 2.The attribution of existence does not define the conception of an object ‘exists’ is not a real predicate

Descartes’s Version Against Kant 1.The attribution of property predicates defines the conception of an object 2.The attribution of existence does not define the conception of an object ‘exists’ is not a property predicate

Descartes’s Version Against Kant 4.‘X’ is a property predicate if X is a property 5.‘exists’ is not a property predicate Existence is not a property

Descartes’s Version Against Kant What makes existence a ‘perfection’ anyway?