Introduction to Philosophy
Lecture 5
The Ontological Argument
By David Kelsey
Saint Anselm
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Saint Anselm of Canterbury lived from 1033-1109.
He was a monk and later Archbishop of Canterbury.
Wanted to see how far argument and reason could substantiate the central
doctrines of Christianity.
He invented the ontological argument for the existence of God.
A priori vs.
A posteriori arguments
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A Posteriori Arguments:
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A priori arguments:
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An a posteriori argument has at least one premise which is contingent. It has at least one premise
that is a question of fact.
Examples: the Cosmological and Teleological arguments for the existence of God
Have absolutely no premises that are a question of fact.
Composed entirely of a priori claims.
An a priori claim: true or false in virtue of the meaning of it’s words alone.
The ontological argument is an a priori argument…
Defining GOD
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According to the Judeao-Christian-Islamic tradition: God is the greatest or
most perfect possible being.
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Thus, God is:
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What can we infer about God from this?
If God is perfect, he has every perfection.
Omnipotent: maximally powerful
Omniscient: maximally knowledgeable
Omnibenevolent: is perfectly good
Omnipresent: is everywhere
What other perfections might there be?
A Reductio
for God’s omnipotence
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An argument that God must be omnipotent:
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Suppose God wasn’t omnipotent.
Then there could be a being more powerful than God.
That would be greater than God.
But God is the greatest of all possible beings.
So God must be omnipotent.
This argument has the form of a reductio ad absurdum.
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Reductio’s always assume the negation of the conclusion they are out to prove.
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The argument then derives a contradiction
• A contradiction:
– Asserts that something both is and isn’t the case
– cannot possibly be true
– The contradiction above:
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The argument then concludes by asserting what it was to prove
The form of the Reductio
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So here is the form of our reductio:
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1. God isn’t omnipotent.
2. Thus, there could be someone more powerful than God.
3. Thus, there could be someone greater than God.
4. But, by definition, God is the greatest possible being; there couldn’t be someone
greater than God.
5. Thus, there both can and can’t be someone greater than God.
6. Thus, (1) is false: God is omnipotent.
Anselm’s
Ontological Argument
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Anselm’s concept of God:
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Anselm uses the notion of God seen in the Judeao-Christian-Islamic tradition.
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For Anselm: God is ‘something than which nothing greater can be conceived’.
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This is not the same concept as the greatest being we can conceive. Such a concept would be
limited by the way us humans conceive of things….
Anselm is assuming the Great chain of being here.
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If you run up and down the chain you find it easy to conceive of beings both lesser and greater.
Your mind is carried to greater and greater things…
The Great Chain of Being
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The Great Chain of Being:
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God created the world ex nihilo, out of nothing.
• The world is entirely dependent upon God.
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Reality is partitioned in graded steps, which are infinitely close to each other.
• Being and nothingness are mixed in all degrees in all things.
• God has the most being, then the angels, then rational creatures, then more
primitive life forms such as dogs, insects, etc., then to inanimate matter, I.e.
rocks…
– Consider a cat…
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There is a direct correlation between being and goodness.
• The more being something has, the more good it has. So God who has the most
being, is completely good. The created world is less good than God, but still
good.
Anselm’s Reductio
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Anselm’s argument is a Reductio Ad Absurdum. The basic form of the
reductio:
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Assume God doesn’t exist
But then God isn’t the being than which nothing greater can be conceived.
But God is the being than which nothing greater can be conceived.
Thus, God exists.
The form of
Anselm’s argument
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Anselm’s argument:
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1. God does not exist.
2. By God is meant that than which nothing greater can be conceived, (or NGC).
3. NGC does not exist (from 1 & 2)
4. So NGC exists in the understanding but not in reality. (from 2 & 3)
5. NGC can be conceived to exist in reality as well as the understanding.
6. If NGC were to exist in reality as well as the understanding, it would be greater.
7. NGC is not NGC (from 4 & 6)
8. NGC cannot exist in the understanding alone. (from 7)
9. NGC must also exist in reality (from 6 & 8)
10. God exists (from 2 & 9)
11. God does not exist and God exists (from 1 & 10)
12. Premise 1 is false (by 1-11 and reductio ad absurdum)
Thus, 13. God exists
Evaluating Anselm’s argument
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Evaluating Anselm’s argument:
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Is Anselm’s argument valid?
Is Anselm’s argument sound?
– Which premises might be false?
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Premise 1…
Premise 2…
Premise 5…
Premise 6…
Denying premise 2
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Denying premise 2:
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Some argue that premise 2 is false.
They say that such a definition of God is incorrect.
Thoughts…
Denying premise 5
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Challenging the fifth premise:
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Can you conceive of God as existing in reality?
Denying premise 6
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Can we deny premise 6:
– We can do this by claiming that existence in reality is not a perfection.
– Thus, a being that existed in both the understanding and in reality is not more prefect
than a being that existed just in the understanding.
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Anselm’s reply would probably go like this: existence entails the ability to use all of
one’s perfections
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Counter: Is existence the kind of thing that can even be a perfection at all?
Defining God into existence
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Hume criticizes the Ontological argument for trying to define God into existence.
– Remember that the ontological argument assumes:
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For Hume though, it may be that thinking of God entails thinking that he exists but this
concerns only relations of ideas not matters of fact.
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You cannot think of God without thinking God exists
A relation of idea is:
– Discoverable by the mere operations of thought, without dependence on anything
existent in the universe…
• A matter of fact is:
– Discoverable by observation of the external world…
So even though thinking God entails thinking he exists, this has nothing to do with whether
God in fact exists.
• So pointing out that the thought of God includes in it the thought of existence doesn’t entail the
truth of the matter of fact that God exists.
• A relation among ideas, even one that is necessary, gets no traction and can have no causal
power on how things are in the world.
• Relations of ideas cannot prove matters of fact. About matters of fact, we must consult
experience.
Refutation by
logical analogy
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Refutation by Logical Analogy:
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Many people think that Anselm’s argument just has to be wrong for it just shows too
much.
– Can’t we give an argument of the same form as Anselm’s, but for an
obviously false conclusion.
• Since the new argument isn’t sound, neither is Anselm’s.
• This move is called Refutation by logical analogy.
Gaunilo’s parody
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Here is the argument:
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Assume: 1. The island than which no greater can be conceived (GPI) does not exist.
2. So GPI exists in the understanding but not in reality. (from 1)
3. GPI can be conceived to exist in reality as well as the understanding.
4. If GPI were to exist in reality as well as the understanding, it would be greater.
5. GPI is not GPI (from 2 & 4)
6. GPI cannot exist in the understanding alone. (from 5)
7. GPI must also exist in reality (from 4 & 6)
8. GPI exists (from 7)
9. GPI does not exist and GPI exists (from 1 & 8)
10. Premise 1 is false (by 1-9 and reductio ad absurdum)
Thus, 11. GPI exists
Anselm’s reply
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Anselm’s possible replies to Gaunilo:
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He could give up or bite the bullet.
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Gaunilo’s argument isn’t valid…
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A premise from Gaunilo’s argument is false…
Anselm’s best reply
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Anselm’s reply:
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Can the greatest possible island even exist in reality?
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Although the greatest possible being could have all the perfections to the
greatest degree, could an island really have them?