The Ontological
Argument
RENE
DESCARTES
He concluded his own
existence by his ability to
think :“Cogito ergo
sum.”
What else can I prove
exists?
A priori things e.g.
Maths...aware of
properties of a
Even if a triangle had
never existed, they
would still have distinct
characteristics...3 sides,
3 angles.
His senses would not
derive those properties
as clearly & distinctly as
his mind.
Descartes wanted to prove what we
can be certain of in the universe.
First part
 God exists as idea in mind.
Certainly, the idea
of God, or a
supremely perfect
being, is one that I
find within me...
 God = ‘supremely perfect being.’
 Relying on innate idea of God people
possess.
 God’s necessarily exists because that is where our
idea of God came from...as imperfect beings we can’t
develop that idea.
...the less do they[God’s
characteristics]appear
capable of proceeding
from me alone...we must
conclude that God
necessarily exists.
Second part
 Existence is a predicate of God.
 As ‘supremely perfect being’ God must possess
existence otherwise that being is not perfect.
 Concludes, God must exist as existence is predicate
of ‘supremely perfect being.’
 God must exist in reality...absurd to think
otherwise...goes against definition.
 God without existence same as mountains without
valleys, triangles without three sides. ...the mind cannot
conceive of
perfection without
also conceiving of
existence...
Descartes responses to possible objections
Objection
 Just because we have
concept doesn’t mean
they exist
Response
 Same is not true when
referring to
God...concept of God
means God exists
I cannot conceive God
unless as
existing...existence
inseparable from
him...necessity of the
existence of God