The Ontological Argument for the existence of God was developed by Anselm in the 12th Century. Since then it has been a topic of conversation and criticism with regard to the argument of God’s existence. Alvin Plantinga is a Christian philosopher teaching at Notre Dame and considered the premier Christian thinker of our time. His Ontological Argument for God uses the logical notion of possible worlds. This notion of possible worlds is used to help distinguish between necessary truths and contingent truths.
Necessary truths are truths that must be true and cannot be false.
Contingent truths happen to be true if all the circumstances line up; contingent truths are not of necessity true. An example of a contingent truth would be: John Smith owns a red Ferrari. It could be true or it could be false.
A necessary truth is: 2 + 2 = 4. A necessary truth must be true, it cannot be false.
2 + 2 = 5 is necessarily false, it cannot ever be true.
We use the notion of possible worlds to help distinguish between these two things. It is possible somewhere that John Smith owns a red Ferrari. It is necessary in every possible world that 2 + 2 = 4. It is not possible in any world that 2 + 2 = 5. This argument attempts to conclude that the existence of God is a necessary truth and is true in all possible worlds. If you have read this far and are not confused, brace yourself:
- There is a possible world in which maximal greatness is instantiated.
- Necessarily, a being is maximally great only if it has maximal excellence in every world.
- Necessarily, a being has maximal excellence in every world if it has omniscience, omnipotence, and moral perfection in every world.
- In the possible world mentioned in (1) above the following proposition is necessarily false: “There is no omnipotent, omniscient, and morally perfect being.”
- A proposition necessarily false in one possible world is necessarily false in all possible worlds, i.e., what is impossible does not change from one world to another.
- Since the actual world is a possible world, the proposition referred to in (4) above is necessarily false there as well.
- Hence, there exists in the actual world, as well as in every possible world, a being who essentially has the qualities of omnipotence, omniscience, and moral perfection.
The bottom line in this argument is the attempt to categorize the existence of this maximal being as a necessary truth.
The form of this argument taken from Class Notes, Christian Apologetics, Dr. Stanley Obitts, Westmont College, April 9, 1981.