most famous formulation is from anslem’s Proslogium
God is that being than which nothing greater can be conceived.
the concept of God exists in understanding
God does not exist in reality (assumed for the purpose of the reductio ad absurdum argument)
we can conceive of God existing in reality and in the understanding
any being existing in reality is greater than a being that exists only in understanding
hence, we can conceive of some being greater than God, the greatest conceivable being
this is a contradiction
hence, it must be that God does exist in reality
uses example of the greatest island to demonstrate that such an island must exist
anslem’s response seems to be simply to assert that gaunilo is wrong without being clear just why that is the case
more sophisticated response is to suggest that islands are the kind of thing that do not have intrinsic maximums, that they increase in greatness by some undending degree
a response to this might be that God’s “greatness” is similar in that all we are able to conceive are incremental increases in those things we think of as attributes of God, an increase in degree, but that we are not truly able to conceive of the supposed maximums necessary to distinguish the island from God in kind
problem of infinite predicates
“ greatest” of all possible attributes is a strange predicate
think of numbers – if i were to suggest that i had a concept of the number than which no greater is conceivable, i would be suggesting i have a concept which is not logically possible. this is because not matter what number i imagine there is always some number greater, namely that number plus one
can one really have a concept of any infinite attribute at all? what does it mean to be all powerful? can one truly conceive of such a thing?
being (existence) is not a proper predicate
it is not a property that can be added to the concept of a thing
it is merely the positing of that thing in some relation to the subject; it is only to say that there is some instantiation of that concept
what kind of sense can it make to say something exists in the absence of other properties?
rowe’s criticism seems to be that any ascription of a property, according to the kantian account, must presuppose that thing to exist, and this is problematic to say the least. but it does not appear that this is the case. indeed, i can find no place in kant where he says any such thing, and i can find several places where he seems to imply quite the opposite.
a hidden premise that seems troubling
without saying so explicitly, anslem assumes that God is a possible being
by defining God as the greatest of all beings, and by including in that greatness existence, we are saying that God cannot be a nonexisting being
by saying that God is possible, we are actually granting that such a thing does exist
this is because as a possible being God is either existing or non-existing. but, as pointed out above, God cannot be nonexisting. hence, God must exist as a result of His being possible in the first place
we are now question-begging in that we assume from our premises the conclusion, and this is fallacious reasoning
biggest problem (to me)
seems to miss the distinction between entertaining ideas and holding beliefs
it seems entirely plausible that one can entertain the idea of a really existent santa clause without actually holding the belief that such a being does, in fact, exist
this would allow the possibility that existence is a predicate that can be ascribed to a concept, but it does not then demonstrate on the basis of this predicate alone that one is forced to believe in the actual existence of the concept entertained