Ontological arguments for Gods existence

What is the ontological argument?

An a priori argument that attempts to prove God's existence through reason and logic alone.

What does 'ontological' mean?

Relating to the nature of being or existence.

What type of argument is the ontological argument?

A priori and deductive.

Who first formulated the ontological argument?

Anselm of Canterbury.

Where is Anselm's ontological argument found?

In Proslogion.

How does Anselm define God?

'That than which nothing greater can be conceived.'

What is Anselm's first ontological argument?

God exists in the understanding, and it is greater to exist in reality than only in the understanding; therefore God exists in reality.

What is meant by existing 'in the understanding'?

Existing as an idea in the mind.

Why does Anselm believe God must exist in reality?

Because a God existing only in the mind would not be the greatest conceivable being.

What is Anselm's second ontological argument?

God is a necessary being and cannot be conceived not to exist.

What is a necessary being?

A being that cannot fail to exist.

What is a contingent being?

A being that may or may not exist.

Why does Anselm claim God is necessary?

Because a being that cannot fail to exist is greater than one that can.

Who criticised Anselm with the Lost Island objection?

Gaunilo.

What is Gaunilo's Lost Island objection?

Using Anselm's logic, one could prove the existence of a perfect island, which is absurd.

What was Gaunilo trying to show?

That existence cannot be proven simply by definition.

How did Anselm respond to Gaunilo?

He argued that his argument applies only to a necessary being, not contingent things like islands.

Who reformulated the ontological argument in the modern period?

René Descartes.

How does Descartes define God?

A supremely perfect being.

What is Descartes' ontological argument?

Existence is a perfection, and since God possesses all perfections, God must exist.

What analogy does Descartes use?

A triangle necessarily has three sides, just as God necessarily has existence.

Why does Descartes think existence belongs to God?

Because a perfect being lacking existence would not be perfect.

Who offered a famous criticism of the ontological argument?

Immanuel Kant.

What is Kant's main criticism?

Existence is not a predicate.

What is a predicate?

A property or characteristic attributed to something.

Why does Kant reject the ontological argument?

Adding existence does not add a property to a concept.

What example does Kant use?

One hundred real coins contain no more properties than one hundred imagined coins.

What does Kant conclude?

You cannot define something into existence.

Who developed a modal version of the ontological argument?

Alvin Plantinga.

What is a possible world?

A way reality could have been.

What is Plantinga's maximally great being?

A being that is omnipotent, omniscient, and morally perfect in every possible world.

What is Plantinga's modal ontological argument?

If it is possible that a maximally great being exists, then it exists in every possible world, including the actual world.

Does Plantinga claim to prove God exists?

He argues that belief in God can be shown to be rational if God's existence is possible.

What is modal logic?

A system of logic dealing with possibility and necessity.

What is one strength of Anselm's argument?

It relies solely on reason and does not depend on observation.

What is one strength of Plantinga's argument?

It uses sophisticated modal logic to defend the idea of a necessary being.

What is one weakness of the ontological argument?

Many people reject the claim that existence is a property or perfection.

What is one weakness of Anselm's argument?

It depends on accepting his definition of God.

What is one weakness of Plantinga's argument?

It only works if God's existence is accepted as genuinely possible.

Why is the ontological argument unique among arguments for God?

It attempts to prove God's existence without using evidence from the world.

What AO2 comparison is important for OCR?

Whether existence can be treated as a perfection or predicate, as Anselm and Descartes claim, or whether Kant is correct that existence is not a property.