The Ontological Argument

Define the Ontological Argument (5)

proof that God exists
define necessary: something which cannot be otherwise
idea of God includes necessity
therefore God must exist
inductive and a priori
P1: God is "that than which nothing greater can be conceived" (Anselm)
P2: God may exist either in the mind alone or in reality
P3: Somethig which exists in reality and in the mind is greeater than something that exists in the mind alone
C: Therefore God must exist in reality and in the mind

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Descartes: God is immutable (can't change/be different), God's nature is to exist (from necessity as concept of supremely perfect being), God without predicate of existence is illogical and so can't be doubted (self evident/analytic facts without empirical proof required)
P1 - God is the supremely perfect being
P2 - a supremely perfect being contains all supreme [erfections
P3 - existence is supreme perfection
C - therefore God as a supremely perfect being exists
- Anselm: existence as predicate = "God exists" is true by definition
- Leibniz: perfections must be simple/positive (cannot be defined in terms of negation by anything), compatible, self-contained and in one being, God fits since so by virtue of existence, he exists
Tillich: God is necessary whilst everything else depends on his existence so it's illogical to say God doesn't exist
Malcolm: God as greatest possible being + by definition, exists in Anselm's second ontological argument, first Ontological Argument requires necessary existence
Plantinga: possible worlds in which maximally great being exists in -> more great to exist in our world -> God as maximally greatest being must exist

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Gaunilo: reductio ad absurdum; just bc one can image a perfect island doesn't mean it exists IRL, same with God, we can imagine him but he doesn't have to exist
RESPONSE
Anselm: God isn't A perfect thing, he is THE perfect things bc he's necessary, islands are contingent and God as most perfect being is necessary since it's greater to be necessary rather than contingent
Gassendi: I can conceive of God without existence
RESPONSE
all divine perfections entail each other: if God is omnipotent, he musn't depend on anything else to exist. Therefore necessary existence
Caterus: Descartes' argument only works IF God exists bc only IF God exists is he omnipotent. Interdependent perfcetions only show the concept of existence is part of the concept of God
RESPONSE
that's it. We can't conceive of God without existence therefore he must exist
Kant: existence isn't a perfection bc it's not a predicate i.e a dog and a dog who exists is the same, doesn't add anything to it; predicate + concept can be separated (if God did exist, he would exist necessarily but doesn't prove existence)
Hume: we can only know things through experience so anything a priori fails

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