The Ontological Argument
Philosophy of Religion 2008
Lecture 3
Preliminaries
 Procedural work – week 5
 Access to online material
 Philosophy of religion and religious doctrine
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.
Arguments for the existence of God
 Not an exhaustive list
 Assess the arguments
 How to respond: are these proofs?
 Cumulative evidence
Arguments for the existence of God
 Ontological arguments
 Cosmological arguments
 Teleological (design) arguments
 Arguments from experience
 Axiological (moral) arguments
 … and the rest!
Ontological arguments
 Arguments from the nature of God: what God is
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)
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)
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)
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)
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
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)
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.
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;

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.

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-nogreater-nature-can be-thought) is ambiguous
Millican: Anselm’s options
Interpretation
Implications
A nature which is so great that no Sound, but proves only the
nature is greater
instantiation of the greatest
instantiated nature (not the
existence of God)
A nature which can be thought so The nature in question may be
exceeded in actual greatness
great that no nature can be
thought greater
A nature which is so great that no If no God exists, then no nature n fact
nature can be thought greater
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.
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)
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?