Thus, on this general line of argument, it is a necessary truth that such a being exists; and this being is the God of traditional Western theism.
I need to go out into the world and conduct some sort of empirical investigation using my senses.
Likewise, if I want to prove that bachelors, unicorns, or viruses don't exist, I must do the same.
One of the most fascinating arguments for the existence of an all-perfect God is the ontological argument.
While there are several different versions of the argument, all purport to show that it is self-contradictory to deny that there exists a greatest possible being.
As the objection is sometimes put, Anselm simply defines things into existence-and this cannot be done.
Gaunilo shared this worry, believing that one could use Anselm's argument to show the existence of all kinds of non-existent things: Now if some one should tell me that there is …
Normally, existential claims don't follow from conceptual claims.
If I want to prove that bachelors, unicorns, or viruses exist, it is not enough just to reflect on the concepts.
We can do so merely by consulting the definition and seeing that it is self-contradictory.
Thus, the very concepts imply that there exist no entities that are both square and circular.