Originally Posted by hsilman
actually, Descartes established the existence of the world regardless of God. He begins the reduction assuming he is being deceived.
Also, Gaunilo's "lost Island" critique (attempting a reduction ad absurdum on the ontological argument) doesn't work because you can't have a perfect island, or a perfect monster. It really only works for God. So perhaps this does make the ontological argument weaker, but it doesn't disprove it.
God IS the greatest conceivable thing (as defined by Anselm). You can't equate anything else to that.