The Ontological Argument for the existence of God

1
The Ontological Argumentfor the existence of
God

• This is the subtitle

2
Ontological

• Means concerned with being

3
This is an example of an a priori argument(
an argument prior to experience)
4
Historical background...

• Proposed by
• Anselm (1033-1109)
• Supported by
• Descartes
• Malcolm
• Plantinga

• Opposed by
• Gaunilo
• Aquinas
• Kant

5
Anselm

• 1033-1109
• born in Italy
• became Archbishop of Canterbury in 1093
• is a canonised saint of the Roman
  Catholic Church
• was influenced by Augustine
• wrote books called Monologion and Proslogion
• also wrote philosophical dialogues, wrote on the
  incarnation, and on logic

6
Anselms argument

• Is found in chapters 2-4 of his work called
  Proslogion

7
Anselms argument

• God is defined as
• a being than which nothing greater can be
  conceived

8

• If it is the greatest, then it must be something
  more than merely existing in peoples thoughts

9
The formal deductive argument goes like this

• God is the greatest possible being (nothing
  greater can be conceived)
• If God exists in the mind alone (only as an
  idea), then a greater being could be imagined to
  exist both in the mind and in reality
• This being would be greater than God
• Thus God cannot exist only as an idea in the mind
• Therefore God exists both in the mind (as an
  idea) and in reality

10
Or putting it another way...it is
self-contradictory to be able to conceive of
something than which nothing greater can be
thought and yet to deny that that something
exists.
11
Anselms line of argument was challenged by a
monk named Gaunilo
12
Gaunilo of Marmoutier

• Gaunilo promptly responded to Anselm
• Gaunilo pointed out that if someone were to
  describe to you a most perfect island and then
  state that it must exist because it is perfect,
  then you would be a fool to believe him

13
A similar argument may be to imagine 1000 in
your pocket
Yep, I can imagine the dosh in my pocket
Doesnt mean it is real though, does it?
14
Anselm developed the argument further to show
that it was impossible to conceive of God as not
existing

• God is the greatest possible being (nothing
  greater can be conceived)
• It is greater to be a necessary being (cannot not
  be) than a contingent being (can cease to exist)
• If God exists only as a contingent being so can
  therefore be imagined not to exist, then a
  greater being could be imagined that cannot be
  conceived not to exist
• This being would then be greater than God
• God is therefore a necessary being

This is known as the second form of the argument
15
I am not seeking to understand in order to
believe, but I believe in order to understand.
For this too I believe that unless I believe, I
shall not understandAnselm (Proslogion)