1. The Ontological Argument
Philosophy of Religion 2008
Lecture 3

2. Preliminaries Procedural work – week 5 Access to online material
Philosophy of religion and religious doctrine

3. Today Issues regarding arguments for God’s existence
Review some of the more central arguments
Versions of the ontological argument:
Descartes
Anselm
Plantinga
Millican/Nagasawa
Suggestions for further reading.

4. Arguments for the existence of God
Not an exhaustive list
Assess the arguments
How to respond: are these proofs?
Cumulative evidence

5. Arguments for the existence of God
Ontological arguments
Cosmological arguments
Teleological (design) arguments
Arguments from experience
Axiological (moral) arguments
… and the rest!

6. Ontological arguments
Arguments from the nature of God: what God is

7. Descartes’ ontological argument
We have the concept of God as a supremely perfect being
Existence is a perfection: a being that exists is more perfect than a being that does not
A supremely perfect being must have all perfections
Therefore God must exist
(Fifth Meditation)

8. Descartes’ ontological argument
It is just as much of a contradiction to think of God (that is, a supremely perfect being) lacking existence (that is, lacking a perfection), as it is to think of a mountain without a valley
(Descartes, from Fifth Meditation, Davies Guide Chapter 32)

9. Gassendi’s objection
… you compare existence with a property … surely, what does not exist has no perfections or imperfections, and what does exist and has several perfections does not have existence as one of its individual perfections; rather its existence is that in virtue of which both the thing itself and its perfections are existent, and that without which we cannot say that the thing possesses the perfections …if a thing lacks existence we do not say that it is imperfect, or deprived of a perfection, but instead that it is nothing at all.
(Gassendi, in Davies Guide Chapter 33)

10. Kant’s objection
Existence is not a real predicate, ‘not a concept of something that could be added to the concept of a thing’ (CPR B626)
Logical predicates and real predicates
When we say ‘God is’ or ‘God exists’:
‘we attach no new predicate to the concept of God, but only posit the subject in itself with all its predicates … as being an object that stands in relation to my concept’ (CPR B627)

11. Anselm’s ontological argument
God is: ‘something than which nothing greater can be conceived’
Even if someone denies God’s existence, they possess the concept of ‘something greater than which nothing can be conceived’,
This something ’exists in their intellect’
Something that exists in reality is greater than something that exists only in thought
So if he is the greatest, God must exist in reality

12. Guanilo’s ‘perfect island’
… they say that there is in the ocean somewhere an island which … is superior everywhere in abundance of riches to all those other lands that men inhabit. Now … I shall easily understand what is said, since nothing is difficult about it. But if he should then go on to say, as though it were a logical consequence of this: you cannot anymore doubt that this island that is more excellent than all other lands truly exists somewhere in reality than you can doubt that it is in your mind; and since it is more excellent to exist not only in the mind alone, but also in reality, therefore it must needs be that it exists [I should think he was joking, or a fool]
(Guanilo in Davies Guide Chapter 30)

13. Plantinga and Malcolm Norman Malcolm:
God’s existence is either impossible (since he could not be brought into existence by anything greater than himself) …
or necessary (since he cannot be brought into existence, he must always have existed).
Since it is not impossible that God exists, Malcolm argues that he must necessarily exist.

14. Plantinga’s own argument I
P1: There is a possible world W in which maximal greatness is instantiated;
P2: Necessarily, a being is maximally great only if it has maximal excellence in every world;
P3: A being has maximal excellence in every world only if it has omniscience, omnipotence and moral perfection in every world;
C1: If the possible world W existed, there would be a being that had maximal excellence (omniscience, omnipotence, moral perfection) in every world;

15. Plantinga’s own argument II
C1: In possible world W, there would be a being that had maximal excellence (omniscience, omnipotence, moral perfection) in every world;
P4: In W it would be logically impossible that there is no being with maximal excellence;
P5: If something is logically impossible in one possible world then it is impossible in all possible worlds (including our own, actual world);
C2: Therefore it is impossible that a maximally excellent being does not exist in our own, actual world.

16. Millican
Reformulating the claim in terms of instantiated natures overcomes most objections
The Guanilo objection: one can always create a parody case
What is the problem that this reveals?
Anselm’s central idea (a-nature-than-which-no-greater-nature-can be-thought) is ambiguous

17. Millican: Anselm’s options
Interpretation
Implications
A nature which is so great that no nature is greater
Sound, but proves only the instantiation of the greatest instantiated nature (not the existence of God)
A nature which can be thought so great that no nature can be thought greater
The nature in question may be exceeded in actual greatness
A nature which is so great that no nature can be thought greater
If no God exists, then no nature n fact is great enough. This phrase fails to denote anything.
The nature which can be thought so great that no nature is greater
Such a nature could be exceeded in actual greatness.

18. Reading Background - arguments for the existence of God
Quinn and Taliaferro Blackwell Companion
Chapter introductions to Davies’ anthology.
Clack and Clack.
Jill Paton Walsh Knowledge of Angels
Ontological argument - introductory
Davies, Introduction Chapter 4 (2nd Edition) or Chapter 5 (3rd edition)
Graham Oppy ‘The ontological argument’ (C&M)
Stanford Encyclopedia of Philosophy (online) ‘Ontological arguments’
More substantial
Norman Malcolm, ’Anselm’s ontological arguments’ Philosophical Review 69 (1960) (also in JH).
Peter Millican ‘The one fatal flaw in Anselm’s argument’ Mind 113 (2004)
Yujin Nagasawa, ‘Millican on the ontological argument’ Mind 116 (2007)

19. Questions
Does any version of the ontological argument show that there must be a maximally great, or maximally excellent, or necessary being?
If so, why? If not, why not?
Would such a being be the God of theism?