Anslem's argument is sound.

[Neo-Scholastic]

Existence is not a predicate.

/thread

I exist.
Daffy Duck does not exist.

Seems pretty basic to me.

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These two premises prove Anselm's argument is correct though secular Academia presents it with the worse bias:
1. It is greater to exist than not to exist (We try to prevent death because we all believe in this).
2. An action that is imagined and intended, is not as good and great as the same action put to practice. That is to say if we wanted to do a good but we didn't, it is not as good as actually doing the act.
To know Anselm's argument, all you need to believe is one premise which is the controversial premise, that is: "Existence is a perfection/greatness/beauty/goodness."
This has been proven, and the rest will be proven easily. He was no dumb person. When we think of ultimate greatness, we cannot define it if it were not a living reality. This is because life is an aspect of ultimate greatness. It is true, and has been proven in the first 2 premises I have shown.
In fact, while true, you don't even have to argue that living is an aspect of every greatness. Just that living is required for a degree of greatness or is part of some of its instance definition.
You can equate imaging being a hero with actually being a hero, but we know the latter is much greater.
So the ultimate one cannot be defined where it not that he exists. And indeed he has been defined for ages.

So, Neo-Platonism, only convincing to someone inclined to Platonism, rather than empiricism. To a room full of empiricists. This won't end well.

Thomas Aquinas was also an empiricist. He didn't think too highly of the Ontological Argument as formulated by Anselm; although, I don't remember his exact objection.