Wednesday, August 04, 2021

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


Here's one way to state Plantinga's modal version of the ontological argument. argument. (Modal logic uses the three modes of being - possible, probable, necessary.)

  1.  God, if he exists, is a necessary being. That is, if God exists at all then he exists in every possible world.
  2. It is [logically] possible that God exists.
  3. If it is possible that God exists, then there is some possible world in which God exists.
  4. If God exists in some possible world then, because he is a necessary being, he exists in all possible worlds.
  5. God, then, exists in all possible worlds.
  6. If God exists in all possible worlds, then he certainly exists in this one.
  7. God, therefore, exists.