Plantinga's Ontological Argument

Alvin Plantinga wrote his Ontological Argument from a background of logic and mathematics and wrote it in the form of a modal argument. Modality refers to the statement’s necessity, possibility or impossibility. For example, is the statement “God exists” necessary, possible or impossible? Plantinga’s argument outlines the concept of possible worlds. A possible world is a complete way that things can be, meaning there is an infinite number of possible worlds for every possible difference in these worlds. For example, a necessary truth is one that is true in every possible world, and a contingent truth is true in some worlds but not others and an impossible truth is one that is untrue in every possible world. Plantinga criticizes Malcolm for unsuccessfully demonstrating God’s existence in all the possible worlds, saying he merely demonstrated the potential of God’s existence in some possible worlds.

Plantinga’s argument goes as follows:

1. There is a possible world W in which there exists a being of maximal greatness.
2. A being of maximal greatness would possess this quality in all possible worlds.
3. A being of maximal greatness is omniscient, omnipotent and has moral perfection in every possible world.
4. In world W there exists a being which is omniscient, omnipotent and has moral perfection.
5. In world W, the proposition “there is no omniscient, omnipotent and morally perfect being” is impossible.
6. What is impossible in one world is impossible in every possible world.
7. This means the proposition “there is no omniscient, omnipotent and morally perfect being” is impossible in the actual world.
8. Therefore, it is necessarily true that an omniscient, omnipotent and morally perfect being exists in every possible world, including the actual world.