The Ontological Argument - valid or debunked?

[Edwardo Piet]

Perhaps it depends on what definition of "possibly" one uses.

Possibly, meaning probability greater than zero?

That's certainly one. It's the standard very broad dictionary definition though Here's another more specific definition of one type of possibility

A logically possible proposition is one which is consistent with the axioms of a given system of logic.

And there are different definitions of probability too. For instance, there is Bayesian probability and frequentist probability