2 Anselm defines God as "That which nothing greater can be conceived"
3 i. The concept of God is
understood. Whatever is
understood exists in the
understanding. So, God
exists in the
3.1 ii. Suppose God only exits in the
understanding, and not in reality. Then a
greater being than God can be conceived -
one that exists in reality. BUT God is
defined as that than which nothing
greater can be conceived. So, no greater
being can be conceived, by definition.But
now we have a contradiction - so our
original supposition was false (that God
only exists in the understanding).
3.1.1 Reductio Ad Absurdum Argument
126.96.36.199 You accept some hypothesis for the sake of argument,
and then you show that the hypothesis leads to a
contradiction, or some other conclusion you know
independently to be false. Hence the hypothesis can't be
true, so it has to be rejected.
3.1.2 This argument is a priori. It
purports to prove God's existence
simply by considering the
definition of God.
4.1 A monk named Guanilo pointed out that if the
argument were good, it could be used to prove
all sorts of conclusions that were too good to
be true. Eg, That there exists a perfect island
than which nothing greater can be conceived;
4.2 Existence is not a predicate.
4.3 "The problem lies in the ambiguity lurking in
the comparison of 'reality' and 'conception'"
(Blackburn) "Real turkeys are heavier than
imagined turkeys" - Imagined turkeys cannot be
compared against real turkeys. i.e. Even if God
only exists in the understanding, it does not
follow that a greater being can be described or
4.4 God does not exist in the understanding. It is
true that we have an idea of God, but he does
not actually exist in the understanding.