Saturday, January 20, 2024

Plantinga's Modal Version of the Ontological Argument for God's Existence

                                                       
                                                       (Pond, at Monroe County Community College)

In my MCCC Philosophy of Religion classes I taught Anselm's Ontological Argument for God's Existence, and modal version of the Ontological Argument. Here is Alvin Plantinga's modal version of the Ontological Argument for God's existence. It is a real head-twister! 

Using modal logic, the following is true: If a necessary being is possible then a necessary being exists. (Think about it, modally.)

Or:

1. There is a possible world in which a necessarily existing being exists.
2. Therefore, a necessarily existing being exists.

Note: This argument avoids the Kantian criticism that 'exists' is not a predicate.


PLANTINGA’S MODAL VERSION OF THE ONTOLOGICAL ARGUMENT FOR GOD’S EXISTENCE


The argument goes:


1.    It is possible that there is a being (B) that has maximal greatness.

2.    So, there is a possible being that in some world W has maximal greatness.

3.    A being has maximal greatness in a given world only if it has maximal excellence in every world.

4.    A being has maximal excellence in a given world only if it has omniscience, omnipotence, and moral perfection in that world.

5.    Therefore, “there actually exists a being (B) that is omnipotent, omniscient, and morally perfect; this being, furthermore, exists and has these qualities in every other world as well.”

Needed to understand this argument:

Logical possibilities and impossibilities do not vary from world to world. If a given proposition or state of affairs is impossible in at least one possible world, then it is impossible in every possible world. For example, "square circles" are logical impossibilities in our world. Therefore they are logical impossibilities in every possible world. There is no possible world, no creatively invented world, that could contain a square circle.
  • There are no propositions that are in fact impossible but could have been possible. For example, square circles could not exist in any conceivable/possible world.
  • And, there are no propositions that in fact are possible but could have been impossible. For example, if there is a possible world in which SpongeBob exists, then there is no possible world in which SpongeBob could not exist.
  • Therefore, B's nonexistence is impossible in every possible world. And because B is a maximally great Being, B exists in every possible world.
  • Therefore B’s nonexistence is impossible in this world (since this world is a possible world).
  • Therefore B exists and exists necessarily.