Investigating the Anselm Existential Demonstration for Proving God's Existence

This article will study one of the old-time demonstrations of proving God's existence in the history of west philosophy which is known as "existential demonstration" and has been known with this label since Kant's time. In this article the historical background of this demonstration in Christian philosophy has been explained and its different aspects and expositions has been mentioned and the two expositions of Anselm demonstration has been elaborately explained. In the first exposition, Anselm proves God’s existence through imagining God as the greatest possible imaginable being and in the second exposition, emphasizes on the necessity of its existence. In this article, I have put attention to philosopher’s viewpoint about existence of one or two types of expositions on “existential demonstration” and I have accepted both of the expositions. This demonstration has encountered several criticisms during its appearance and emergence which started by Ghoniloo from the time of Anselm himself and continued by Thomas Aquinas and Kant and it is still discussed by people such as John Hick and others. The essence of these criticisms is that just by imagining something, one cannot prove its objective being. I have concluded that no matter how much the commentators and acceptors have tried, they have not been able to eliminate the problems of this demonstration which is nothing other than confusion of concept and it’s referent and expecting the effects of an objective being from a conceptual being and also confusion of the boundary between logic and metaphysics.