Work on the ontological argument since 1970 has been mainly concerned with the so-called modal ontological argument for the existence of a perfect being.

The Concept of a Perfect Being

Descartes defined a (supremely) perfect being as a being that possesses all perfections. But if a property F is a perfection, it would seem that a being that is F but might not have been F falls short of perfection. Hence a better definition of a perfect being would be as follows: a being that has all perfections and could not have lacked any perfection—a perfect being is a being that has all perfections essentially (has all perfections in every possible world in which it exists).

The Logical Validity of the Modal Ontological Argument

The argument has two premises: (1) A perfect being is possible...