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Transcript
Ontological Argument
• Recap on Plantinga’s version of the
ontological argument.
• Examine the criticisms of his
version.
Alvin Plantinga
1. It is possible that there be a being that has
maximal greatness.
2. So there is a possible being that in some world
W has maximal greatness.
3. A being has maximal greatness in a given world
only if it has maximal excellence in every world.
4. A being has maximal excellence in a given world
only if it has omniscience, omnipotence, and
moral perfection in that world.
Alvin Plantinga
• Plantinga argues that this reformulation of
the OA removes the issue of necessary
existence.
• ‘…we no longer need the supposition that
necessary existence is a perfection; for
obviously a being can’t be omnipotent…in a
given world unless it exists in that world.’
Alvin Plantinga
2. So there is a possible being that in
some world W has maximal greatness.
• If W is actual then it would be impossible
that there be no omnipotent, omniscient,
and morally perfect being.
• Contingent truths vary from world to
world, what is logically impossible does not.
Alvin Plantinga
‘Therefore, in every possible world W it is
impossible that there be no such being……hence
it is impossible in the actual world……Hence there
really does exist a being who is omniscient,
omnipotent, and morally perfect and who exists
and has these properties in every possible world.’
Alvin Plantinga: addressing objections
1. It is possible that there be a being
that has maximal greatness.
• What are possible beings?
• Are they merely possible beings that don’t
in fact exist?
• Plantinga offers the suggestion that his
version of the OA seems to make sense
only on this assumption.
Alvin Plantinga: addressing objections
1. It is possible that there be a being
that has maximal greatness.
• The above premise can make sense if we
are prepared to grant that there are
possible beings who don’t in fact exist.
• Plantinga argues this is either unintelligible
or necessarily false.
Alvin Plantinga: addressing objections
• So can his reformulation of the OA
survive?
• Yes! [Well he thinks so!]
• He replaces talking of possible beings with
talking of properties and their existence.
Alvin Plantinga
1.
It is possible that there be
a being that has maximal
greatness.
2.
So there is a possible being
that in some world W has
maximal greatness.
3.
A being has maximal
greatness in a given world
only if it has maximal
excellence in every world.
4.
A being has maximal
excellence in a given world
only if it has omniscience,
omnipotence, and moral
perfection in that world.
1.
Maximal greatness is possibly
instantiated. [i.e. an abstract
concept is represented by an actual
example.]
2.
There is a possible world in which
maximal greatness is instantiated
3.
Necessarily, a being is maximally
great only if it has maximal
excellence in every world.
4.
Necessarily, a being has maximal
excellence in every world only if it
has omniscience, omnipotence, and
moral perfection in every world.
Alvin Plantinga
1.
2.
3.
4.
Maximal greatness is possibly
instantiated. [i.e. an abstract
concept is represented by an
actual example.]
If 2 is true then it follows that if the
There is a possible world in which possible world is actual, it would have
maximal greatness is instantiated been impossible that there be no such
Necessarily, a being is maximally being.
great only if it has maximal
excellence in every world.
Notice that 3 and 4 do not
Necessarily, a being has maximal
imply that there are
excellence in every world only if
possible but non-existent
it has omniscience, omnipotence,
beings.
and moral perfection in every
world.
Alvin Plantinga
1. If W had been actual, then ‘there is no omnipotent,
omniscient, and morally perfect being’ would be an
impossible proposition.
2. If a proposition is impossible in at least one possible
word, then it is impossible in every possible world.
3. Accordingly, it is impossible in the actual world.
4. If it is impossible then there actually exists a being
that is omnipotent, omniscient, and morally perfect;
this being has these qualities and exists in every
possible world.
Alvin Plantinga: Self-Review!
1. The argument is valid; given its premise, the
conclusion follows.
2. Only question is whether its main premise - that
maximal greatness is possible instantiated - is true.
3. P thinks it is true therefore his version is sound.
4. Says there is ‘nothing contrary to reason or
irrational in accepting this premise.’
5. Is this a proof of the existence of God? NO!
Criticisms of Plantinga:
See Lacewing pp198.
•
Appeals to a possible world to show that the
existence of a maximally excellent being is logically
necessary in this world.
•
Has failed to show that the possible world must be
real. It only exists in the realm of logic.
•
Mackie, ‘The Miracle of Theism’, accuses Plantinga of
“……subverting all the principles of the understanding
of so many intelligent readers.”