Carl Sagan on The ontological argument
Sagan regarded the ontological argument as a verbal trick that confuses concepts with realities.
Sagan did not devote extensive attention to the ontological argument, but his broader philosophical commitments make his position clear. As a scientist and empiricist, he held that the existence of things in the world is established by observation and evidence, not by the analysis of concepts. The ontological argument's attempt to prove God's existence from the definition of God struck him as fundamentally misguided — a confusion of the map with the territory.
In his public lectures and writings, Sagan frequently warned against the tendency to mistake our concepts for reality. Human beings are prone to reifying their ideas — treating abstractions as though they were concrete things. The ontological argument is, from this perspective, a sophisticated example of a common cognitive error: concluding that because we can conceive of something, it must exist.
Sagan's empiricism demanded that existence claims be supported by evidence, not by argument alone. The greatest being conceivable may or may not exist; the way to find out is to look, not to reason from definitions. And when we look, Sagan argued, we find a universe that is magnificent but shows no sign of being arranged by the kind of being the ontological argument describes.
“Extraordinary claims require extraordinary evidence.”