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St Anselm’s ontological argument
- This is an a priori, deductive argument for the existence of God. Thus, its
conclusion is known through reason alone - independently of sense
experience and the truth of the premises guarantees the truth of the
conclusion
- Anselm argues that “that than which nothing greater can be conceived”
(hereafter, the Greatest Conceivable Being (GCB)) must exist.
- P1: The concept of a being than which none greater can be conceived (ie the
GCB) exists as a (coherent) concept in the mind (in the ‘understanding’).
- P2: Suppose, for reductio, that the GCB exists only in the mind and not in
reality.
- P3: A being that exists in the mind and in reality is greater than a being that
exists only in the mind.
- C1: Therefore, there is something greater than the GCB
- Anselm’s can be seen as a “reductio ad absurdum” argument – i.e. it
shows that the assumption that the GCB only exists in the mind leads
to a contradiction and should therefore be rejected.
- C2: Therefore (denial of P2), the GCB must exist in the mind and in reality.
- C3: Therefore, God exists in the mind and in reality.
Descarte’s ontological argument
- This is an a priori, deductive argument for the existence of God. Thus, its
conclusion is known through reason alone - independently of sense
, experience and the truth of the premises guarantees the truth of the
conclusion
- Descartes defines God as a supremely perfect being
- P1: He (or we) have a clear and distinct idea of God
- His idea is ‘open and present to the attending mind’ and precise and
separated from other ideas so that it ‘plainly contains in itself nothing
other than what is clear.’
- P2: The idea of God is the idea of a supremely perfect being
- The ontological argument is not merely a proof but is a self-evident
axiom grasped intuitively by a mind free from philosophical prejudice
- P3: A supremely perfect being (God) has all perfections
- Each perfection is necessary condition
- P4: Existence is a perfection
- C: Therefore, a supremely perfect being (God) must exist
Malcom’s ontological argument
- This is an a priori, deductive argument for the existence of God. Thus, its
conclusion is known through reason alone - independently of sense
experience and the truth of the premises guarantees the truth of the
conclusion
- Malcom bases his argument upon model theory and through a process of
elimination he concludes that God existence is not necessarily false, not
contingently false and not contingently true but necessarily true
- P1: God is conceived as an unlimited/infinite being
- P2: Either God does not exist or God exists.
- P3: If God does not exist then God’s existence would be impossible
- This is because God cannot come into existence: it would either mean
that his existence was caused by something else or just “happened” to
occur, both of which would mean that God was limited.
- P4: If God does exist then God’s existence must be necessary
- This is because God cannot come into or go out of existence: it would
mean again that either God’s existence/demise was caused by
, something else or just “happened” to occur, both of which would mean
that God was limited.
- C1: Therefore, God’s existence is either impossible or necessary.
- P5: If God’s existence is impossible then the concept must be
self-contradictory.
- P6: The concept of a necessary being (God) is not self-contradictory (it is
coherent)
- C2: Therefore, God’s existence is not impossible.
- C3: Therefore, by process of elimination, God’s existence is necessary (God
must exist).
Gaunilo’s perfect island objection
- Gaunilo claims that this argument, if it were valid, could be applied equally
well to the greatest conceivable species of object – his example being the
greatest conceivable island.
- P1: The concept of an island than which none greater can be imagined (ie,
the greatest conceivable island/the GCI) exists as a (coherent) concept in the
mind (in the ‘understanding’).
- P2: Suppose, for reductio, that the GCI exists only in the mind and not in
reality.
- P3: An island that exists in the mind and in reality is greater than an island
that exists only in the mind.
- C1: Therefore, there is an island greater than the GCI.
- This reformulation of Anselm’s argument, like the original, is a
“reductio ad absurdum” argument – i.e. it shows that the assumption
that the GCI only exists in the mind leads to a contradiction and should
therefore be rejected.
- C2: Therefore (denial of P2), the GCI must exist in the mind and in reality.
- C3: Therefore, the GCI exists.
- Therefore, via a reductio ad absurdum argument, Gaunilo argues that
Anselm’s original argument must be invalid, given that if it worked it would
justify absurd conclusions.
,Empiricist objections to a priori arguments for existence
- Ontological arguments claim that “God exists” is an analytic, necessary truth.
- The negation of an analytic/necessary truth involves a contradiction and
therefore cannot be coherently conceived.
- “God does not exist” can be coherently conceived without contradiction.
- Therefore, “God does not exist” is not a contradiction.
- Therefore, “God exists” cannot be an analytic, necessary truth.
- If God’s existence is not analytic/necessary, then it is synthetic and
contingent - a matter of fact about "what exists and what is the case”.
- According to Hume, matters of fact cannot be established a priori; they
require a posteriori justification.
- Therefore, God’s existence could only be established a posteriori, if at all.
- Therefore, the ontological argument fails to prove God’s existence a priori
merely from the concept of God.
Kant's objection based on existence not being a predicate
- A predicate is a term, property, or characteristic that is affirmed or denied
about a subject in a proposition.
- Kant questions the fourth premise in Descartes’ argument: ‘Existence is a
perfection’.
- To make such a claim is to treat ‘exists’ like other predicates (or ‘perfections’)
such as ‘wise’, ‘powerful’ or ‘blue’. However, ‘exists’ does not work in this way.
- Saying something ‘exists’ does not give you more information about that
thing, as saying it is ‘wise’ or ‘blue’ does.
- For example, Kant uses the example of a hundred thalers to illustrate his
point. If you imagine 100 thalers, and then imagine those same 100 thalers
existing in reality, the concept of the 100 thalers doesn't change. The
properties of the imagined thalers and the real thalers are exactly the same
and their existence doesn't add any new predicate to the concept of them.
- Rather than adding to a concept’s description, ‘existence’ ‘substantiates’ a
concept, i.e. it says that there is a thing in the physical world that
corresponds to the concept.
- In using ‘existence’ as a predicate, Descartes is trying to argue that ‘God
exists’ is an analytic proposition.
, - A ‘normal’ analytic proposition, such as ‘a brother is a male sibling’ unpacks
the concept ‘brother’, adding to the description of ‘brother’. As ‘existence’
does not add to the description of a concept, it follows that any statement of
the form ‘X exists’ cannot be an analytic statement.
- Rather, it must always be a synthetic statement.
- Moreover, Kant distinguishes between the logical necessity within a concept
and its actual existence.
- Even if necessary existence were a predicate, this would tell us nothing by
itself about whether God actually exists in reality.
- Kant uses Descartes’ example of a triangle to illustrate this. It is necessarily
true that a triangle has three sides: we could not conceive of a triangle while
denying that it has three sides without contradiction.
- However, this does not mean that anything 3 sided necessarily exists.
- We can logically deny that any triangle exists, and if no triangle exists, then
there are no three-sided shapes either.
- Kant applies the same reasoning to the ontological argument. The argument
may establish that necessary existence belongs to the concept or definition
of God. However, it does not establish that the being corresponding to that
necessary property actually exists. At most, it shows that if God exists, then
God exists necessarily.
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3/
St Anselm’s ontological argument
- This is an a priori, deductive argument for the existence of God. Thus, its
conclusion is known through reason alone - independently of sense
experience and the truth of the premises guarantees the truth of the
conclusion
- Anselm argues that “that than which nothing greater can be conceived”
(hereafter, the Greatest Conceivable Being (GCB)) must exist.
- P1: The concept of a being than which none greater can be conceived (ie the
GCB) exists as a (coherent) concept in the mind (in the ‘understanding’).
- P2: Suppose, for reductio, that the GCB exists only in the mind and not in
reality.
- P3: A being that exists in the mind and in reality is greater than a being that
exists only in the mind.
- C1: Therefore, there is something greater than the GCB
- Anselm’s can be seen as a “reductio ad absurdum” argument – i.e. it
shows that the assumption that the GCB only exists in the mind leads
to a contradiction and should therefore be rejected.
- C2: Therefore (denial of P2), the GCB must exist in the mind and in reality.
- C3: Therefore, God exists in the mind and in reality.
Descarte’s ontological argument
- This is an a priori, deductive argument for the existence of God. Thus, its
conclusion is known through reason alone - independently of sense
, experience and the truth of the premises guarantees the truth of the
conclusion
- Descartes defines God as a supremely perfect being
- P1: He (or we) have a clear and distinct idea of God
- His idea is ‘open and present to the attending mind’ and precise and
separated from other ideas so that it ‘plainly contains in itself nothing
other than what is clear.’
- P2: The idea of God is the idea of a supremely perfect being
- The ontological argument is not merely a proof but is a self-evident
axiom grasped intuitively by a mind free from philosophical prejudice
- P3: A supremely perfect being (God) has all perfections
- Each perfection is necessary condition
- P4: Existence is a perfection
- C: Therefore, a supremely perfect being (God) must exist
Malcom’s ontological argument
- This is an a priori, deductive argument for the existence of God. Thus, its
conclusion is known through reason alone - independently of sense
experience and the truth of the premises guarantees the truth of the
conclusion
- Malcom bases his argument upon model theory and through a process of
elimination he concludes that God existence is not necessarily false, not
contingently false and not contingently true but necessarily true
- P1: God is conceived as an unlimited/infinite being
- P2: Either God does not exist or God exists.
- P3: If God does not exist then God’s existence would be impossible
- This is because God cannot come into existence: it would either mean
that his existence was caused by something else or just “happened” to
occur, both of which would mean that God was limited.
- P4: If God does exist then God’s existence must be necessary
- This is because God cannot come into or go out of existence: it would
mean again that either God’s existence/demise was caused by
, something else or just “happened” to occur, both of which would mean
that God was limited.
- C1: Therefore, God’s existence is either impossible or necessary.
- P5: If God’s existence is impossible then the concept must be
self-contradictory.
- P6: The concept of a necessary being (God) is not self-contradictory (it is
coherent)
- C2: Therefore, God’s existence is not impossible.
- C3: Therefore, by process of elimination, God’s existence is necessary (God
must exist).
Gaunilo’s perfect island objection
- Gaunilo claims that this argument, if it were valid, could be applied equally
well to the greatest conceivable species of object – his example being the
greatest conceivable island.
- P1: The concept of an island than which none greater can be imagined (ie,
the greatest conceivable island/the GCI) exists as a (coherent) concept in the
mind (in the ‘understanding’).
- P2: Suppose, for reductio, that the GCI exists only in the mind and not in
reality.
- P3: An island that exists in the mind and in reality is greater than an island
that exists only in the mind.
- C1: Therefore, there is an island greater than the GCI.
- This reformulation of Anselm’s argument, like the original, is a
“reductio ad absurdum” argument – i.e. it shows that the assumption
that the GCI only exists in the mind leads to a contradiction and should
therefore be rejected.
- C2: Therefore (denial of P2), the GCI must exist in the mind and in reality.
- C3: Therefore, the GCI exists.
- Therefore, via a reductio ad absurdum argument, Gaunilo argues that
Anselm’s original argument must be invalid, given that if it worked it would
justify absurd conclusions.
,Empiricist objections to a priori arguments for existence
- Ontological arguments claim that “God exists” is an analytic, necessary truth.
- The negation of an analytic/necessary truth involves a contradiction and
therefore cannot be coherently conceived.
- “God does not exist” can be coherently conceived without contradiction.
- Therefore, “God does not exist” is not a contradiction.
- Therefore, “God exists” cannot be an analytic, necessary truth.
- If God’s existence is not analytic/necessary, then it is synthetic and
contingent - a matter of fact about "what exists and what is the case”.
- According to Hume, matters of fact cannot be established a priori; they
require a posteriori justification.
- Therefore, God’s existence could only be established a posteriori, if at all.
- Therefore, the ontological argument fails to prove God’s existence a priori
merely from the concept of God.
Kant's objection based on existence not being a predicate
- A predicate is a term, property, or characteristic that is affirmed or denied
about a subject in a proposition.
- Kant questions the fourth premise in Descartes’ argument: ‘Existence is a
perfection’.
- To make such a claim is to treat ‘exists’ like other predicates (or ‘perfections’)
such as ‘wise’, ‘powerful’ or ‘blue’. However, ‘exists’ does not work in this way.
- Saying something ‘exists’ does not give you more information about that
thing, as saying it is ‘wise’ or ‘blue’ does.
- For example, Kant uses the example of a hundred thalers to illustrate his
point. If you imagine 100 thalers, and then imagine those same 100 thalers
existing in reality, the concept of the 100 thalers doesn't change. The
properties of the imagined thalers and the real thalers are exactly the same
and their existence doesn't add any new predicate to the concept of them.
- Rather than adding to a concept’s description, ‘existence’ ‘substantiates’ a
concept, i.e. it says that there is a thing in the physical world that
corresponds to the concept.
- In using ‘existence’ as a predicate, Descartes is trying to argue that ‘God
exists’ is an analytic proposition.
, - A ‘normal’ analytic proposition, such as ‘a brother is a male sibling’ unpacks
the concept ‘brother’, adding to the description of ‘brother’. As ‘existence’
does not add to the description of a concept, it follows that any statement of
the form ‘X exists’ cannot be an analytic statement.
- Rather, it must always be a synthetic statement.
- Moreover, Kant distinguishes between the logical necessity within a concept
and its actual existence.
- Even if necessary existence were a predicate, this would tell us nothing by
itself about whether God actually exists in reality.
- Kant uses Descartes’ example of a triangle to illustrate this. It is necessarily
true that a triangle has three sides: we could not conceive of a triangle while
denying that it has three sides without contradiction.
- However, this does not mean that anything 3 sided necessarily exists.
- We can logically deny that any triangle exists, and if no triangle exists, then
there are no three-sided shapes either.
- Kant applies the same reasoning to the ontological argument. The argument
may establish that necessary existence belongs to the concept or definition
of God. However, it does not establish that the being corresponding to that
necessary property actually exists. At most, it shows that if God exists, then
God exists necessarily.
