Plantinga's ontological argument

Alvin Plantinga's version of the ontological argument suggests that the concept of a maximally great being—often identified as God—implies its existence. If we can conceive of a being greater than any other, it must exist in reality because existing in reality makes a being greater than one that exists only in the mind. Thus, if it's possible for such a perfect being to exist, then it exists necessarily somewhere—arguably, in all possible worlds—and necessarily so. Plantinga's approach emphasizes that the very idea or concept of a most perfect being entails its existence.