2) The Ontological Argument
Alvin Plantinga, the John A. O’Brien Professor of Philosophy Emeritus at the University of Notre Dame, is a juggernaut in the history of modern philosophy of religion. He is almost single-handedly responsible for the current renaissance, in philosophy departments around the world, of Christian theism. Dr. Plantinga, is particularly well-known for an argument, based on the study of being, known as the Ontological Argument — an argument first developed by St. Anselm in his 11th century work Proslogion. Anselm framed it like this:
The fool hath said in his heart, “there is no God.” But that same fool understands what he means when he says “God” (a being that which greater cannot be thought). And that understanding exists in his mind. But it cannot exist only in the mind; for it could also be thought of as existing in reality as well — which is greater.
The argument demonstrates that if the idea of a being that which greater cannot be thought is logically possible, then it follows that such a being is also logically necessary. For if that being exists in one possible world, it must exist in all of them (it is greater to exist in every possible world, than in any number less). Here is Dr. Plantinga’s version of the argument:
Possible World: A total description of a possible reality
Maximal excellence: To have omnipotence, omniscience and moral perfection in some world.
Maximal greatness: To have maximal excellence in every possible world.
1) There is a possible world (W) in which there is a being (X) with maximal greatness.
2) But X is maximally great only if X has maximal excellence in every possible world.
3) Therefore X is maximally great only if X has omnipotence, omniscience and moral perfection in every possible world.
4) In W, the proposition “There is no omnipotent, omniscient, morally perfect being” would be impossible—that is, necessarily false.
5) But what is impossible does not vary from world to world.
6) Therefore, the proposition, “There is no omnipotent, omniscient, morally perfect being” is necessarily false in this actual world, too.
7) Therefore, there actually exists in this world, and must exist in every possible world, an omnipotent, omniscient, morally perfect being.